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501
What is (are) glucose-6-phosphate dehydrogenase deficiency ?
Glucose-6-phosphate dehydrogenase deficiency is a genetic disorder that occurs most often in males. This condition mainly affects red blood cells, which carry oxygen from the lungs to tissues throughout the body. In affected individuals, a defect in an enzyme called glucose-6-phosphate dehydrogenase causes red blood cells to break down prematurely. This destruction of red blood cells is called hemolysis. The most common medical problem associated with glucose-6-phosphate dehydrogenase deficiency is hemolytic anemia, which occurs when red blood cells are destroyed faster than the body can replace them. This type of anemia leads to paleness, yellowing of the skin and whites of the eyes (jaundice), dark urine, fatigue, shortness of breath, and a rapid heart rate. In people with glucose-6-dehydrogenase deficiency, hemolytic anemia is most often triggered by bacterial or viral infections or by certain drugs (such as some antibiotics and medications used to treat malaria). Hemolytic anemia can also occur after eating fava beans or inhaling pollen from fava plants (a reaction called favism). Glucose-6-dehydrogenase deficiency is also a significant cause of mild to severe jaundice in newborns. Many people with this disorder, however, never experience any signs or symptoms.
growth_hormone_receptor
hemolytic anemia
502
How many people are affected by glucose-6-phosphate dehydrogenase deficiency ?
An estimated 400 million people worldwide have glucose-6-phosphate dehydrogenase deficiency. This condition occurs most frequently in certain parts of Africa, Asia, and the Mediterranean. It affects about 1 in 10 African American males in the United States.
growth_hormone_receptor
400 million
503
What are the genetic changes related to glucose-6-phosphate dehydrogenase deficiency ?
Mutations in the G6PD gene cause glucose-6-phosphate dehydrogenase deficiency. The G6PD gene provides instructions for making an enzyme called glucose-6-phosphate dehydrogenase. This enzyme is involved in the normal processing of carbohydrates. It also protects red blood cells from the effects of potentially harmful molecules called reactive oxygen species. Reactive oxygen species are byproducts of normal cellular functions. Chemical reactions involving glucose-6-phosphate dehydrogenase produce compounds that prevent reactive oxygen species from building up to toxic levels within red blood cells. If mutations in the G6PD gene reduce the amount of glucose-6-phosphate dehydrogenase or alter its structure, this enzyme can no longer play its protective role. As a result, reactive oxygen species can accumulate and damage red blood cells. Factors such as infections, certain drugs, or ingesting fava beans can increase the levels of reactive oxygen species, causing red blood cells to be destroyed faster than the body can replace them. A reduction in the amount of red blood cells causes the signs and symptoms of hemolytic anemia. Researchers believe that carriers of a G6PD mutation may be partially protected against malaria, an infectious disease carried by a certain type of mosquito. A reduction in the amount of functional glucose-6-dehydrogenase appears to make it more difficult for this parasite to invade red blood cells. Glucose-6-phosphate dehydrogenase deficiency occurs most frequently in areas of the world where malaria is common.
growth_hormone_receptor
Mutations in the G6PD gene
504
Is glucose-6-phosphate dehydrogenase deficiency inherited ?
This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
growth_hormone_receptor
This condition is inherited in an X-linked recessive pattern
505
What are the treatments for glucose-6-phosphate dehydrogenase deficiency ?
These resources address the diagnosis or management of glucose-6-phosphate dehydrogenase deficiency: - Baby's First Test - Genetic Testing Registry: Glucose 6 phosphate dehydrogenase deficiency - MedlinePlus Encyclopedia: Glucose-6-phosphate dehydrogenase deficiency - MedlinePlus Encyclopedia: Glucose-6-phosphate dehydrogenase test - MedlinePlus Encyclopedia: Hemolytic anemia - MedlinePlus Encyclopedia: Newborn jaundice These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Diagnostic Tests - Drug Therapy - Surgery
506
What is (are) Gilbert syndrome ?
Gilbert syndrome is a relatively mild condition characterized by periods of elevated levels of a toxic substance called bilirubin in the blood (hyperbilirubinemia). Bilirubin, which has an orange-yellow tint, is produced when red blood cells are broken down. This substance is removed from the body only after it undergoes a chemical reaction in the liver, which converts the toxic form of bilirubin (unconjugated bilirubin) to a nontoxic form called conjugated bilirubin. People with Gilbert syndrome have a buildup of unconjugated bilirubin in their blood (unconjugated hyperbilirubinemia). In affected individuals, bilirubin levels fluctuate and very rarely increase to levels that cause jaundice, which is yellowing of the skin and whites of the eyes. Gilbert syndrome is usually recognized in adolescence. If people with this condition have episodes of hyperbilirubinemia, these episodes are generally mild and typically occur when the body is under stress, for instance because of dehydration, prolonged periods without food (fasting), illness, vigorous exercise, or menstruation. Some people with Gilbert syndrome also experience abdominal discomfort or tiredness. However, approximately 30 percent of people with Gilbert syndrome have no signs or symptoms of the condition and are discovered only when routine blood tests reveal elevated unconjugated bilirubin levels.
growth_hormone_receptor
a relatively mild condition
507
How many people are affected by Gilbert syndrome ?
Gilbert syndrome is a common condition that is estimated to affect 3 to 7 percent of Americans.
growth_hormone_receptor
3 to 7 percent
508
What are the genetic changes related to Gilbert syndrome ?
Changes in the UGT1A1 gene cause Gilbert syndrome. This gene provides instructions for making the bilirubin uridine diphosphate glucuronosyltransferase (bilirubin-UGT) enzyme, which is found primarily in liver cells and is necessary for the removal of bilirubin from the body. The bilirubin-UGT enzyme performs a chemical reaction called glucuronidation. During this reaction, the enzyme transfers a compound called glucuronic acid to unconjugated bilirubin, converting it to conjugated bilirubin. Glucuronidation makes bilirubin dissolvable in water so that it can be removed from the body. Gilbert syndrome occurs worldwide, but some mutations occur more often in particular populations. In many populations, the most common genetic change that causes Gilbert syndrome (known as UGT1A1*28) occurs in an area near the UGT1A1 gene called the promoter region, which controls the production of the bilirubin-UGT enzyme. This genetic change impairs enzyme production. However, this change is uncommon in Asian populations, and affected Asians often have a mutation that changes a single protein building block (amino acid) in the bilirubin-UGT enzyme. This type of mutation, known as a missense mutation, results in reduced enzyme function. People with Gilbert syndrome have approximately 30 percent of normal bilirubin-UGT enzyme function. As a result, unconjugated bilirubin is not glucuronidated quickly enough. This toxic substance then builds up in the body, causing mild hyperbilirubinemia. Not everyone with the genetic changes that cause Gilbert syndrome develops hyperbilirubinemia, indicating that additional factors, such as conditions that further hinder the glucuronidation process, may be necessary for development of the condition. For example, red blood cells may break down too easily, releasing excess amounts of bilirubin that the impaired enzyme cannot keep up with. Alternatively, movement of bilirubin into the liver, where it would be glucuronidated, may be impaired. These other factors may be due to changes in other genes.
growth_hormone_receptor
hyperbilirubinemia
509
Is Gilbert syndrome inherited ?
Gilbert syndrome can have different inheritance patterns. When the condition is caused by the UGT1A1*28 change in the promoter region of the UGT1A1 gene, it is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have the mutation. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. When the condition is caused by a missense mutation in the UGT1A1 gene, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. A more severe condition known as Crigler-Najjar syndrome occurs when both copies of the UGT1A1 gene have mutations.
growth_hormone_receptor
different inheritance patterns
510
What are the treatments for Gilbert syndrome ?
These resources address the diagnosis or management of Gilbert syndrome: - Genetic Testing Registry: Gilbert's syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Genetic Testing Registry
511
What is (are) familial Mediterranean fever ?
Familial Mediterranean fever is an inherited condition characterized by recurrent episodes of painful inflammation in the abdomen, chest, or joints. These episodes are often accompanied by fever and sometimes a rash or headache. Occasionally inflammation may occur in other parts of the body, such as the heart; the membrane surrounding the brain and spinal cord; and in males, the testicles. In about half of affected individuals, attacks are preceded by mild signs and symptoms known as a prodrome. Prodromal symptoms include mildly uncomfortable sensations in the area that will later become inflamed, or more general feelings of discomfort. The first episode of illness in familial Mediterranean fever usually occurs in childhood or the teenage years, but in some cases, the initial attack occurs much later in life. Typically, episodes last 12 to 72 hours and can vary in severity. The length of time between attacks is also variable and can range from days to years. During these periods, affected individuals usually have no signs or symptoms related to the condition. However, without treatment to help prevent attacks and complications, a buildup of protein deposits (amyloidosis) in the body's organs and tissues may occur, especially in the kidneys, which can lead to kidney failure.
growth_hormone_receptor
an inherited condition
512
How many people are affected by familial Mediterranean fever ?
Familial Mediterranean fever primarily affects populations originating in the Mediterranean region, particularly people of Armenian, Arab, Turkish, or Jewish ancestry. The disorder affects 1 in 200 to 1,000 people in these populations. It is less common in other populations.
growth_hormone_receptor
1 in 200 to 1,000
513
What are the genetic changes related to familial Mediterranean fever ?
Mutations in the MEFV gene cause familial Mediterranean fever. The MEFV gene provides instructions for making a protein called pyrin (also known as marenostrin), which is found in white blood cells. This protein is involved in the immune system, helping to regulate the process of inflammation. Inflammation occurs when the immune system sends signaling molecules and white blood cells to a site of injury or disease to fight microbial invaders and facilitate tissue repair. When this process is complete, the body stops the inflammatory response to prevent damage to its own cells and tissues. Mutations in the MEFV gene reduce the activity of the pyrin protein, which disrupts control of the inflammation process. An inappropriate or prolonged inflammatory response can result, leading to fever and pain in the abdomen, chest, or joints. Normal variations in the SAA1 gene may modify the course of familial Mediterranean fever. Some evidence suggests that a particular version of the SAA1 gene (called the alpha variant) increases the risk of amyloidosis among people with familial Mediterranean fever.
growth_hormone_receptor
Normal variations in the SAA1 gene
514
Is familial Mediterranean fever inherited ?
Familial Mediterranean fever is almost always inherited in an autosomal recessive pattern, which means both copies of the MEFV gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. In rare cases, this condition appears to be inherited in an autosomal dominant pattern. An autosomal dominant inheritance pattern describes cases in which one copy of the altered gene in each cell is sufficient to cause the disorder. In autosomal dominant inheritance, affected individuals often inherit the mutation from one affected parent. However, another mechanism is believed to account for some cases of familial Mediterranean fever that were originally thought to be inherited in an autosomal dominant pattern. A gene mutation that occurs frequently in a population may result in a disorder with autosomal recessive inheritance appearing in multiple generations in a family, a pattern that mimics autosomal dominant inheritance. If one parent has familial Mediterranean fever (with mutations in both copies of the MEFV gene in each cell) and the other parent is an unaffected carrier (with a mutation in one copy of the MEFV gene in each cell), it may appear as if the affected child inherited the disorder only from the affected parent. This appearance of autosomal dominant inheritance when the pattern is actually autosomal recessive is called pseudodominance.
growth_hormone_receptor
almost always inherited in an autosomal recessive pattern
515
What are the treatments for familial Mediterranean fever ?
These resources address the diagnosis or management of familial Mediterranean fever: - Gene Review: Gene Review: Familial Mediterranean Fever - Genetic Testing Registry: Familial Mediterranean fever These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Surgery and Rehabilitation - Genetic Counseling - Palliative Care
516
What is (are) familial glucocorticoid deficiency ?
Familial glucocorticoid deficiency is a condition that occurs when the adrenal glands, which are hormone-producing glands located on top of each kidney, do not produce certain hormones called glucocorticoids. These hormones, which include cortisol and corticosterone, aid in immune system function, play a role in maintaining normal blood sugar levels, help trigger nerve cell signaling in the brain, and serve many other purposes in the body. A shortage of adrenal hormones (adrenal insufficiency) causes the signs and symptoms of familial glucocorticoid deficiency. These signs and symptoms often begin in infancy or early childhood. Most affected children first develop low blood sugar (hypoglycemia). These hypoglycemic children can fail to grow and gain weight at the expected rate (failure to thrive). If left untreated, hypoglycemia can lead to seizures, learning difficulties, and other neurological problems. Hypoglycemia that is left untreated for prolonged periods can lead to neurological damage and death. Other features of familial glucocorticoid deficiency can include recurrent infections and skin coloring darker than that of other family members (hyperpigmentation). There are multiple types of familial glucocorticoid deficiency, which are distinguished by their genetic cause.
growth_hormone_receptor
a condition that occurs when the adrenal glands
517
How many people are affected by familial glucocorticoid deficiency ?
The prevalence of familial glucocorticoid deficiency is unknown.
growth_hormone_receptor
unknown
518
What are the genetic changes related to familial glucocorticoid deficiency ?
Mutations in the MC2R, MRAP, and NNT genes account for the majority of cases of familial glucocorticoid deficiency; mutations in other genes, some known and some unidentified, can also cause this condition. The MC2R gene provides instructions for making a protein called adrenocorticotropic hormone (ACTH) receptor, which is found primarily in the adrenal glands. The protein produced from the MRAP gene transports the ACTH receptor from the interior of the cell to the cell membrane. When the ACTH receptor is embedded within the cell membrane, it is turned on (activated) by the MRAP protein. Activated ACTH receptor can then attach (bind) to ACTH, and this binding triggers the adrenal glands to produce glucocorticoids. MC2R gene mutations lead to the production of a receptor that cannot be transported to the cell membrane or, if it does get to the cell membrane, cannot bind to ACTH. MRAP gene mutations impair the transport of the ACTH receptor to the cell membrane. Without the binding of the ACTH receptor to its hormone, there is no signal to trigger the adrenal glands to produce glucocorticoids. The NNT gene provides instructions for making an enzyme called nicotinamide nucleotide transhydrogenase. This enzyme is found embedded in the inner membrane of structures called mitochondria, which are the energy-producing centers of cells. This enzyme helps produce a substance called NADPH, which is involved in removing potentially toxic molecules called reactive oxygen species that can damage DNA, proteins, and cell membranes. NNT gene mutations impair the enzyme's ability to produce NADPH, leading to an increase in reactive oxygen species in adrenal gland tissues. Over time, these toxic molecules can impair the function of adrenal gland cells and lead to their death (apoptosis), diminishing the production of glucocorticoids.
growth_hormone_receptor
MC2R, MRAP, and NNT genes
519
Is familial glucocorticoid deficiency inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
This condition is inherited in an autosomal recessive pattern
520
What are the treatments for familial glucocorticoid deficiency ?
These resources address the diagnosis or management of familial glucocorticoid deficiency: - Genetic Testing Registry: ACTH resistance - Genetic Testing Registry: Glucocorticoid deficiency 2 - Genetic Testing Registry: Glucocorticoid deficiency 3 - Genetic Testing Registry: Glucocorticoid deficiency 4 - Genetic Testing Registry: Natural killer cell deficiency, familial isolated These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
ACTH resistance - Genetic Testing Registry
521
What is (are) X-linked juvenile retinoschisis ?
X-linked juvenile retinoschisis is a condition characterized by impaired vision that begins in childhood and occurs almost exclusively in males. This disorder affects the retina, which is a specialized light-sensitive tissue that lines the back of the eye. Damage to the retina impairs the sharpness of vision (visual acuity) in both eyes. Typically, X-linked juvenile retinoschisis affects cells in the central area of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. X-linked juvenile retinoschisis is one type of a broader disorder called macular degeneration, which disrupts the normal functioning of the macula. Occasionally, side (peripheral) vision is affected in people with X-linked juvenile retinoschisis. X-linked juvenile retinoschisis is usually diagnosed when affected boys start school and poor vision and difficulty with reading become apparent. In more severe cases, eye squinting and involuntary movement of the eyes (nystagmus) begin in infancy. Other early features of X-linked juvenile retinoschisis include eyes that do not look in the same direction (strabismus) and farsightedness (hyperopia). Visual acuity often declines in childhood and adolescence but then stabilizes throughout adulthood until a significant decline in visual acuity typically occurs in a man's fifties or sixties. Sometimes, severe complications develop, such as separation of the retinal layers (retinal detachment) or leakage of blood vessels in the retina (vitreous hemorrhage). These eye abnormalities can further impair vision or cause blindness.
growth_hormone_receptor
macular degeneration
522
How many people are affected by X-linked juvenile retinoschisis ?
The prevalence of X-linked juvenile retinoschisis is estimated to be 1 in 5,000 to 25,000 men worldwide.
growth_hormone_receptor
1 in 5,000 to 25,000
523
What are the genetic changes related to X-linked juvenile retinoschisis ?
Mutations in the RS1 gene cause most cases of X-linked juvenile retinoschisis. The RS1 gene provides instructions for making a protein called retinoschisin, which is found in the retina. Studies suggest that retinoschisin plays a role in the development and maintenance of the retina. The protein is probably involved in the organization of cells in the retina by attaching cells together (cell adhesion). RS1 gene mutations result in a decrease in or complete loss of functional retinoschisin, which disrupts the maintenance and organization of cells in the retina. As a result, tiny splits (schisis) or tears form in the retina. This damage often forms a "spoke-wheel" pattern in the macula, which can be seen during an eye examination. In half of affected individuals, these abnormalities can occur in the area of the macula, affecting visual acuity, in the other half of cases the schisis occurs in the sides of the retina, resulting in impaired peripheral vision. Some individuals with X-linked juvenile retinoschisis do not have a mutation in the RS1 gene. In these individuals, the cause of the disorder is unknown.
growth_hormone_receptor
do not have a mutation in the RS1 gene
524
Is X-linked juvenile retinoschisis inherited ?
This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
growth_hormone_receptor
This condition is inherited in an X-linked recessive pattern
525
What are the treatments for X-linked juvenile retinoschisis ?
These resources address the diagnosis or management of X-linked juvenile retinoschisis: - Gene Review: Gene Review: X-Linked Juvenile Retinoschisis - Genetic Testing Registry: Juvenile retinoschisis These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Diagnostic Tests - Drug Therapy - Surgery
526
What is (are) Wolman disease ?
Wolman disease is a rare inherited condition involving the breakdown and use of fats and cholesterol in the body (lipid metabolism). In affected individuals, harmful amounts of lipids accumulate in the spleen, liver, bone marrow, small intestine, small hormone-producing glands on top of each kidney (adrenal glands), and lymph nodes. In addition to fat deposits, calcium deposits in the adrenal glands are also seen. Infants with Wolman disease are healthy and active at birth but soon develop signs and symptoms of the disorder. These may include an enlarged liver and spleen (hepatosplenomegaly), poor weight gain, low muscle tone, a yellow tint to the skin and the whites of the eyes (jaundice), vomiting, diarrhea, developmental delay, low amounts of iron in the blood (anemia), and poor absorption of nutrients from food. Children affected by this condition develop severe malnutrition and generally do not survive past early childhood.
growth_hormone_receptor
a rare inherited condition
527
How many people are affected by Wolman disease ?
Wolman disease is estimated to occur in 1 in 350,000 newborns.
growth_hormone_receptor
1 in 350,000
528
What are the genetic changes related to Wolman disease ?
Mutations in the LIPA gene cause Wolman disease. The LIPA gene provides instructions for producing an enzyme called lysosomal acid lipase. This enzyme is found in the lysosomes (compartments that digest and recycle materials in the cell), where it processes lipids such as cholesteryl esters and triglycerides so they can be used by the body. Mutations in this gene lead to a shortage of lysosomal acid lipase and the accumulation of triglycerides, cholesteryl esters, and other kinds of fats within the cells and tissues of affected individuals. This accumulation as well as malnutrition caused by the body's inability to use lipids properly result in the signs and symptoms of Wolman disease.
growth_hormone_receptor
malnutrition
529
Is Wolman disease inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
This condition is inherited in an autosomal recessive pattern
530
What are the treatments for Wolman disease ?
These resources address the diagnosis or management of Wolman disease: - Genetic Testing Registry: Lysosomal acid lipase deficiency These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Genetic Testing Registry: Lysosomal acid lipase deficiency
531
What is (are) 3MC syndrome ?
3MC syndrome is a disorder characterized by unusual facial features and problems affecting other tissues and organs of the body. The distinctive facial features of people with 3MC syndrome include widely spaced eyes (hypertelorism), a narrowing of the eye opening (blepharophimosis), droopy eyelids (ptosis), highly arched eyebrows, and an opening in the upper lip (cleft lip) with an opening in the roof of the mouth (cleft palate). Common features affecting other body systems include developmental delay, intellectual disability, hearing loss, and slow growth after birth resulting in short stature. Other features of 3MC syndrome can include abnormal fusion of certain bones in the skull (craniosynostosis) or forearm (radioulnar synostosis); an outgrowth of the tailbone (caudal appendage); a soft out-pouching around the belly-button (an umbilical hernia); and abnormalities of the kidneys, bladder, or genitals. 3MC syndrome encompasses four disorders that were formerly considered to be separate: Mingarelli, Malpeuch, Michels, and Carnevale syndromes. Researchers now generally consider these disorders to be part of the same condition, which is called 3MC based on the initials of the older condition names.
growth_hormone_receptor
unusual facial features and problems affecting other tissues and organs of the body
532
How many people are affected by 3MC syndrome ?
3MC syndrome is a rare disorder; its exact prevalence is unknown.
growth_hormone_receptor
unknown
533
What are the genetic changes related to 3MC syndrome ?
3MC syndrome is caused by mutations in the COLEC11 or MASP1 gene. These genes provide instructions for making proteins that are involved in a series of reactions called the lectin complement pathway. This pathway is thought to help direct the movement (migration) of cells during early development before birth to form the organs and systems of the body. It appears to be particularly important in directing the migration of neural crest cells, which give rise to various tissues including many tissues in the face and skull, the glands that produce hormones (endocrine glands), and portions of the nervous system. The COLEC11 gene provides instructions for making a protein called CL-K1. Three different proteins, MASP-1, MASP-3, and MAp44 can be produced from the MASP1 gene, depending on how the gene's instructions are pieced together. The MASP1 gene mutations identified in people with 3MC syndrome affect the MASP-3 protein; some affect the MASP-1 protein in addition to MASP-3. COLEC11 and MASP1 gene mutations that cause 3MC syndrome impair or eliminate the function of the corresponding proteins, resulting in faulty control of cell migration in embryonic development and leading to the various abnormalities that occur in this disorder. In some people with 3MC syndrome, no mutations in the COLEC11 or MASP1 gene have been identified. In these individuals, the cause of the disorder is unknown.
growth_hormone_receptor
no mutations in the COLEC11 or MASP1 gene
534
Is 3MC syndrome inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
autosomal recessive pattern
535
What are the treatments for 3MC syndrome ?
These resources address the diagnosis or management of 3MC syndrome: - Genetic Testing Registry: Carnevale syndrome - Genetic Testing Registry: Craniofacial-ulnar-renal syndrome - Genetic Testing Registry: Malpuech facial clefting syndrome - Genetic Testing Registry: Michels syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Genetic Testing Registry
536
What is (are) Lynch syndrome ?
Lynch syndrome, often called hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited disorder that increases the risk of many types of cancer, particularly cancers of the colon (large intestine) and rectum, which are collectively referred to as colorectal cancer. People with Lynch syndrome also have an increased risk of cancers of the stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, and skin. Additionally, women with this disorder have a high risk of cancer of the ovaries and lining of the uterus (the endometrium). People with Lynch syndrome may occasionally have noncancerous (benign) growths (polyps) in the colon, called colon polyps. In individuals with this disorder, colon polyps occur earlier but not in greater numbers than they do in the general population.
growth_hormone_receptor
an inherited disorder that increases the risk of many types of cancer
537
How many people are affected by Lynch syndrome ?
In the United States, about 140,000 new cases of colorectal cancer are diagnosed each year. Approximately 3 to 5 percent of these cancers are caused by Lynch syndrome.
growth_hormone_receptor
3 to 5 percent
538
What are the genetic changes related to Lynch syndrome ?
Variations in the MLH1, MSH2, MSH6, PMS2, or EPCAM gene increase the risk of developing Lynch syndrome. The MLH1, MSH2, MSH6, and PMS2 genes are involved in the repair of mistakes that occur when DNA is copied in preparation for cell division (a process called DNA replication). Mutations in any of these genes prevent the proper repair of DNA replication mistakes. As the abnormal cells continue to divide, the accumulated mistakes can lead to uncontrolled cell growth and possibly cancer. Mutations in the EPCAM gene also lead to impaired DNA repair, although the gene is not itself involved in this process. The EPCAM gene lies next to the MSH2 gene on chromosome 2; certain EPCAM gene mutations cause the MSH2 gene to be turned off (inactivated), interrupting DNA repair and leading to accumulated DNA mistakes. Although mutations in these genes predispose individuals to cancer, not all people who carry these mutations develop cancerous tumors.
growth_hormone_receptor
PMS2, or EPCAM gene
539
Is Lynch syndrome inherited ?
Lynch syndrome cancer risk is inherited in an autosomal dominant pattern, which means one inherited copy of the altered gene in each cell is sufficient to increase cancer risk. It is important to note that people inherit an increased risk of cancer, not the disease itself. Not all people who inherit mutations in these genes will develop cancer.
growth_hormone_receptor
Lynch syndrome cancer risk is inherited in an autosomal dominant pattern
540
What are the treatments for Lynch syndrome ?
These resources address the diagnosis or management of Lynch syndrome: - American Medical Association and National Coalition for Health Professional Education in Genetics: Understand the Basics of Genetic Testing for Hereditary Colorectal Cancer - Gene Review: Gene Review: Lynch Syndrome - GeneFacts: Lynch Syndrome: Management - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 3 - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 4 - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 5 - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 8 - Genetic Testing Registry: Lynch syndrome - Genetic Testing Registry: Lynch syndrome I - Genetic Testing Registry: Lynch syndrome II - Genomics Education Programme (UK) - MedlinePlus Encyclopedia: Colon Cancer - National Cancer Institute: Genetic Testing for Hereditary Cancer Syndromes These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
American Medical Association and National Coalition for Health Professional Education in Genetics
541
What is (are) childhood myocerebrohepatopathy spectrum ?
Childhood myocerebrohepatopathy spectrum, commonly called MCHS, is part of a group of conditions called the POLG-related disorders. The conditions in this group feature a range of similar signs and symptoms involving muscle-, nerve-, and brain-related functions. MCHS typically becomes apparent in children from a few months to 3 years old. People with this condition usually have problems with their muscles (myo-), brain (cerebro-), and liver (hepato-). Common signs and symptoms of MCHS include muscle weakness (myopathy), developmental delay or a deterioration of intellectual function, and liver disease. Another possible sign of this condition is a toxic buildup of lactic acid in the body (lactic acidosis). Often, affected children are unable to gain weight and grow at the expected rate (failure to thrive). Additional signs and symptoms of MCHS can include a form of kidney disease called renal tubular acidosis, inflammation of the pancreas (pancreatitis), recurrent episodes of nausea and vomiting (cyclic vomiting), or hearing loss.
growth_hormone_receptor
MCHS
542
How many people are affected by childhood myocerebrohepatopathy spectrum ?
The prevalence of childhood myocerebrohepatopathy spectrum is unknown.
growth_hormone_receptor
unknown
543
What are the genetic changes related to childhood myocerebrohepatopathy spectrum ?
MCHS is caused by mutations in the POLG gene. This gene provides instructions for making one part, the alpha subunit, of a protein called polymerase gamma (pol ). Pol functions in mitochondria, which are structures within cells that use oxygen to convert the energy from food into a form cells can use. Mitochondria each contain a small amount of DNA, known as mitochondrial DNA (mtDNA), which is essential for the normal function of these structures. Pol "reads" sequences of mtDNA and uses them as templates to produce new copies of mtDNA in a process called DNA replication. Most POLG gene mutations change single protein building blocks (amino acids) in the alpha subunit of pol . These changes result in a mutated pol that has a reduced ability to replicate DNA. Although the mechanism is unknown, mutations in the POLG gene often result in fewer copies of mtDNA (mtDNA depletion), particularly in muscle, brain, or liver cells. MtDNA depletion causes a decrease in cellular energy, which could account for the signs and symptoms of MCHS.
growth_hormone_receptor
single protein building blocks
544
Is childhood myocerebrohepatopathy spectrum inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
autosomal recessive pattern
545
What are the treatments for childhood myocerebrohepatopathy spectrum ?
These resources address the diagnosis or management of MCHS: - Gene Review: Gene Review: POLG-Related Disorders - United Mitochondrial Disease Foundation: Diagnosis of Mitochondrial Disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Surgery and Rehabilitation - Genetic Counseling - Palliative Care
546
What is (are) celiac disease ?
Celiac disease is a condition in which the immune system is abnormally sensitive to gluten, a protein found in wheat, rye, and barley. Celiac disease is an autoimmune disorder; autoimmune disorders occur when the immune system malfunctions and attacks the body's own tissues and organs. Without a strict, lifelong gluten-free diet, inflammation resulting from immune system overactivity may cause a wide variety of signs and symptoms involving many parts of the body. Celiac disease can develop at any age after an individual starts eating foods containing gluten. The classic symptoms of the condition result from inflammation affecting the gastrointestinal tract. This inflammation damages the villi, which are small, finger-like projections that line the small intestine and provide a greatly increased surface area to absorb nutrients. In celiac disease, the villi become shortened and eventually flatten out. Intestinal damage causes diarrhea and poor absorption of nutrients, which may lead to weight loss. Abdominal pain, swelling (distention), and food intolerances are common in celiac disease. Inflammation associated with celiac disease may lead to an increased risk of developing certain gastrointestinal cancers such as cancers of the small intestine or esophagus. Inflammation and poor nutrient absorption may lead to problems affecting many other organs and systems of the body in affected individuals. These health problems may include iron deficiency that results in a low number of red blood cells (anemia), vitamin deficiencies, low bone mineral density (osteoporosis), itchy skin rashes (dermatitis herpetiformis), defects in the enamel of the teeth, chronic fatigue, joint pain, poor growth, delayed puberty, infertility, or repeated miscarriages. Neurological problems have also been associated with celiac disease; these include migraine headaches, depression, attention deficit hyperactivity disorder (ADHD), and recurrent seizures (epilepsy). Many people with celiac disease have one or more of these varied health problems but do not have gastrointestinal symptoms. This form of the condition is called nonclassic celiac disease. Researchers now believe that nonclassic celiac disease is actually more common than the classic form. Celiac disease often goes undiagnosed because many of its signs and symptoms are nonspecific, which means they may occur in many disorders. Most people who have one or more of these nonspecific health problems do not have celiac disease. On average, a diagnosis of celiac disease is not made until 6 to 10 years after symptoms begin. Some people have silent celiac disease, in which they have no symptoms of the disorder. However, people with silent celiac disease do have immune proteins in their blood (antibodies) that are common in celiac disease. They also have inflammatory damage to their small intestine that can be detected with a biopsy. In a small number of cases, celiac disease does not improve with a gluten-free diet and progresses to a condition called refractory sprue. Refractory sprue is characterized by chronic inflammation of the gastrointestinal tract, poor absorption of nutrients, and an increased risk of developing a type of cancer of the immune cells called T-cell lymphoma.
growth_hormone_receptor
autoimmune disorder
547
How many people are affected by celiac disease ?
Celiac disease is a common disorder. Its prevalence has been estimated at about 1 in 100 people worldwide.
growth_hormone_receptor
1 in 100
548
What are the genetic changes related to celiac disease ?
The risk of developing celiac disease is increased by certain variants of the HLA-DQA1 and HLA-DQB1 genes. These genes provide instructions for making proteins that play a critical role in the immune system. The HLA-DQA1 and HLA-DQB1 genes belong to a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders such as viruses and bacteria. The proteins produced from the HLA-DQA1 and HLA-DQB1 genes attach (bind) to each other to form a functional protein complex called an antigen-binding DQ heterodimer. This complex, which is present on the surface of certain immune system cells, attaches to protein fragments (peptides) outside the cell. If the immune system recognizes the peptides as foreign (such as viral or bacterial peptides), it triggers a response to attack the invading viruses or bacteria. Celiac disease is associated with an inappropriate immune response to a segment of the gluten protein called gliadin. This inappropriate activation of the immune system causes inflammation that damages the body's organs and tissues and leads to the signs and symptoms of celiac disease. Almost all people with celiac disease have specific variants of the HLA-DQA1 and HLA-DQB1 genes, which seem to increase the risk of an inappropriate immune response to gliadin. However, these variants are also found in 30 percent of the general population, and only 3 percent of individuals with the gene variants develop celiac disease. It appears likely that other contributors, such as environmental factors and changes in other genes, also influence the development of this complex disorder.
growth_hormone_receptor
environmental factors and changes in other genes
549
Is celiac disease inherited ?
Celiac disease tends to cluster in families. Parents, siblings, or children (first-degree relatives) of people with celiac disease have between a 4 and 15 percent chance of developing the disorder. However, the inheritance pattern is unknown.
growth_hormone_receptor
the inheritance pattern is unknown
550
What are the treatments for celiac disease ?
These resources address the diagnosis or management of celiac disease: - Beth Israel Deaconess: Celiac Center - Columbia University Celiac Disease Center - Gene Review: Gene Review: Celiac Disease - Genetic Testing Registry: Celiac disease - Massachusetts General Hospital Center for Celiac Research and Treatment - MedlinePlus Encyclopedia: Celiac Disease Nutritional Considerations - North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition: Gluten-Free Diet Guide - University of Chicago Celiac Disease Center These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
diagnosis or management
551
What is (are) long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency ?
Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency is a rare condition that prevents the body from converting certain fats to energy, particularly during periods without food (fasting). Signs and symptoms of LCHAD deficiency typically appear during infancy or early childhood and can include feeding difficulties, lack of energy (lethargy), low blood sugar (hypoglycemia), weak muscle tone (hypotonia), liver problems, and abnormalities in the light-sensitive tissue at the back of the eye (retina). Later in childhood, people with this condition may experience muscle pain, breakdown of muscle tissue, and a loss of sensation in their arms and legs (peripheral neuropathy). Individuals with LCHAD deficiency are also at risk for serious heart problems, breathing difficulties, coma, and sudden death. Problems related to LCHAD deficiency can be triggered by periods of fasting or by illnesses such as viral infections. This disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.
growth_hormone_receptor
prevents the body from converting certain fats to energy
552
How many people are affected by long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency ?
The incidence of LCHAD deficiency is unknown. One estimate, based on a Finnish population, indicates that 1 in 62,000 pregnancies is affected by this disorder. In the United States, the incidence is probably much lower.
growth_hormone_receptor
1 in 62,000
553
What are the genetic changes related to long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency ?
Mutations in the HADHA gene cause LCHAD deficiency. The HADHA gene provides instructions for making part of an enzyme complex called mitochondrial trifunctional protein. This enzyme complex functions in mitochondria, the energy-producing centers within cells. As the name suggests, mitochondrial trifunctional protein contains three enzymes that each perform a different function. This enzyme complex is required to break down (metabolize) a group of fats called long-chain fatty acids. Long-chain fatty acids are found in foods such as milk and certain oils. These fatty acids are stored in the body's fat tissues. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, fatty acids are also an important energy source for the liver and other tissues. Mutations in the HADHA gene that cause LCHAD deficiency disrupt one of the functions of this enzyme complex. These mutations prevent the normal processing of long-chain fatty acids from food and body fat. As a result, these fatty acids are not converted to energy, which can lead to some features of this disorder, such as lethargy and hypoglycemia. Long-chain fatty acids or partially metabolized fatty acids may also build up and damage the liver, heart, muscles, and retina. This abnormal buildup causes the other signs and symptoms of LCHAD deficiency.
growth_hormone_receptor
Long-chain fatty acids are found in foods such as milk and certain oils
554
Is long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
This condition is inherited in an autosomal recessive pattern
555
What are the treatments for long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency ?
These resources address the diagnosis or management of LCHAD deficiency: - Baby's First Test - Genetic Testing Registry: Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency - MedlinePlus Encyclopedia: Hypoglycemia - MedlinePlus Encyclopedia: Peripheral Neuropathy These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Baby's First Test - Genetic Testing Registry
556
What is (are) Meesmann corneal dystrophy ?
Meesmann corneal dystrophy is an eye disease that affects the cornea, which is the clear front covering of the eye. This condition is characterized by the formation of tiny round cysts in the outermost layer of the cornea, called the corneal epithelium. This part of the cornea acts as a barrier to help prevent foreign materials, such as dust and bacteria, from entering the eye. In people with Meesmann corneal dystrophy, cysts can appear as early as the first year of life. They usually affect both eyes and increase in number over time. The cysts usually do not cause any symptoms until late adolescence or adulthood, when they start to break open (rupture) on the surface of the cornea and cause irritation. The resulting symptoms typically include increased sensitivity to light (photophobia), twitching of the eyelids (blepharospasm), increased tear production, the sensation of having a foreign object in the eye, and an inability to tolerate wearing contact lenses. Some affected individuals also have temporary episodes of blurred vision.
growth_hormone_receptor
eye disease
557
How many people are affected by Meesmann corneal dystrophy ?
Meesmann corneal dystrophy is a rare disorder whose prevalence is unknown. It was first described in a large, multi-generational German family with more than 100 affected members. Since then, the condition has been reported in individuals and families worldwide.
growth_hormone_receptor
more than 100
558
What are the genetic changes related to Meesmann corneal dystrophy ?
Meesmann corneal dystrophy can result from mutations in either the KRT12 gene or the KRT3 gene. These genes provide instructions for making proteins called keratin 12 and keratin 3, which are found in the corneal epithelium. The two proteins interact to form the structural framework of this layer of the cornea. Mutations in either the KRT12 or KRT3 gene weaken this framework, causing the corneal epithelium to become fragile and to develop the cysts that characterize the disorder. The cysts likely contain clumps of abnormal keratin proteins and other cellular debris. When the cysts rupture, they cause eye irritation and the other symptoms of Meesmann corneal dystrophy.
growth_hormone_receptor
KRT12 gene or the KRT3 gene
559
Is Meesmann corneal dystrophy inherited ?
This condition is inherited in an autosomal dominant pattern, which means one copy of an altered KRT12 or KRT3 gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the condition from an affected parent.
growth_hormone_receptor
This condition is inherited in an autosomal dominant pattern
560
What are the treatments for Meesmann corneal dystrophy ?
These resources address the diagnosis or management of Meesmann corneal dystrophy: - Genetic Testing Registry: Meesman's corneal dystrophy - Merck Manual Home Health Handbook: Tests for Eye Disorders: The Eye Examination These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Genetic Testing Registry
561
What is (are) prostate cancer ?
Prostate cancer is a common disease that affects men, usually in middle age or later. In this disorder, certain cells in the prostate become abnormal and multiply without control or order to form a tumor. The prostate is a gland that surrounds the male urethra and helps produce semen, the fluid that carries sperm. Early prostate cancer usually does not cause pain, and most affected men exhibit no noticeable symptoms. Men are often diagnosed as the result of health screenings, such as a blood test for a substance called prostate specific antigen (PSA) or a medical procedure called a digital rectal exam. As the tumor grows larger, signs and symptoms can include difficulty starting or stopping the flow of urine, a feeling of not being able to empty the bladder completely, blood in the urine or semen, or pain with ejaculation. However, these changes can also occur with many other genitourinary conditions. Having one or more of these symptoms does not necessarily mean that a man has prostate cancer. The severity and outcome of prostate cancer varies widely. Early-stage prostate cancer can usually be treated successfully, and some older men have prostate tumors that grow so slowly that they may never cause health problems during their lifetime, even without treatment. In other men, however, the cancer is much more aggressive; in these cases, prostate cancer can be life-threatening. Some cancerous tumors can invade surrounding tissue and spread to other parts of the body. Tumors that begin at one site and then spread to other areas of the body are called metastatic cancers. The signs and symptoms of metastatic cancer depend on where the disease has spread. If prostate cancer spreads, cancerous cells most often appear in the lymph nodes, bones, lungs, liver, or brain. Bone metastases of prostate cancer most often cause pain in the lower back, pelvis, or hips. A small percentage of all prostate cancers cluster in families. These hereditary cancers are associated with inherited gene mutations. Hereditary prostate cancers tend to develop earlier in life than non-inherited (sporadic) cases.
growth_hormone_receptor
a gland that surrounds the male urethra
562
How many people are affected by prostate cancer ?
About 1 in 7 men will be diagnosed with prostate cancer at some time during their life. In addition, studies indicate that many older men have undiagnosed prostate cancer that is non-aggressive and unlikely to cause symptoms or affect their lifespan. While most men who are diagnosed with prostate cancer do not die from it, this common cancer is still the second leading cause of cancer death among men in the United States. More than 60 percent of prostate cancers are diagnosed after age 65, and the disorder is rare before age 40. In the United States, African Americans have a higher risk of developing prostate cancer than do men of other ethnic backgrounds, and they also have a higher risk of dying from the disease.
growth_hormone_receptor
1 in 7
563
What are the genetic changes related to prostate cancer ?
Cancers occur when genetic mutations build up in critical genes, specifically those that control cell growth and division or the repair of damaged DNA. These changes allow cells to grow and divide uncontrollably to form a tumor. In most cases of prostate cancer, these genetic changes are acquired during a man's lifetime and are present only in certain cells in the prostate. These changes, which are called somatic mutations, are not inherited. Somatic mutations in many different genes have been found in prostate cancer cells. Less commonly, genetic changes present in essentially all of the body's cells increase the risk of developing prostate cancer. These genetic changes, which are classified as germline mutations, are usually inherited from a parent. In people with germline mutations, changes in other genes, together with environmental and lifestyle factors, also influence whether a person will develop prostate cancer. Inherited mutations in particular genes, such as BRCA1, BRCA2, and HOXB13, account for some cases of hereditary prostate cancer. Men with mutations in these genes have a high risk of developing prostate cancer and, in some cases, other cancers during their lifetimes. In addition, men with BRCA2 or HOXB13 gene mutations may have a higher risk of developing life-threatening forms of prostate cancer. The proteins produced from the BRCA1 and BRCA2 genes are involved in fixing damaged DNA, which helps to maintain the stability of a cell's genetic information. For this reason, the BRCA1 and BRCA2 proteins are considered to be tumor suppressors, which means that they help keep cells from growing and dividing too fast or in an uncontrolled way. Mutations in these genes impair the cell's ability to fix damaged DNA, allowing potentially damaging mutations to persist. As these defects accumulate, they can trigger cells to grow and divide uncontrollably and form a tumor. The HOXB13 gene provides instructions for producing a protein that attaches (binds) to specific regions of DNA and regulates the activity of other genes. On the basis of this role, the protein produced from the HOXB13 gene is called a transcription factor. Like BRCA1 and BRCA2, the HOXB13 protein is thought to act as a tumor suppressor. HOXB13 gene mutations may result in impairment of the protein's tumor suppressor function, resulting in the uncontrolled cell growth and division that can lead to prostate cancer. Inherited variations in dozens of other genes have been studied as possible risk factors for prostate cancer. Some of these genes provide instructions for making proteins that interact with the proteins produced from the BRCA1, BRCA2, or HOXB13 genes. Others act as tumor suppressors through different pathways. Changes in these genes probably make only a small contribution to overall prostate cancer risk. However, researchers suspect that the combined influence of variations in many of these genes may significantly impact a person's risk of developing this form of cancer. In many families, the genetic changes associated with hereditary prostate cancer are unknown. Identifying additional genetic risk factors for prostate cancer is an active area of medical research. In addition to genetic changes, researchers have identified many personal and environmental factors that may contribute to a person's risk of developing prostate cancer. These factors include a high-fat diet that includes an excess of meat and dairy and not enough vegetables, a largely inactive (sedentary) lifestyle, obesity, excessive alcohol use, or exposure to certain toxic chemicals. A history of prostate cancer in closely related family members is also an important risk factor, particularly if the cancer occurred at an early age.
growth_hormone_receptor
germline mutations, are usually inherited from a parent
564
Is prostate cancer inherited ?
Many cases of prostate cancer are not related to inherited gene changes. These cancers are associated with somatic mutations that occur only in certain cells in the prostate. When prostate cancer is related to inherited gene changes, the way that cancer risk is inherited depends on the gene involved. For example, mutations in the BRCA1, BRCA2, and HOXB13 genes are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to increase a person's chance of developing cancer. In other cases, the inheritance of prostate cancer risk is unclear. It is important to note that people inherit an increased risk of cancer, not the disease itself. Not all people who inherit mutations in these genes will develop cancer.
growth_hormone_receptor
Many cases of prostate cancer are not related to inherited gene changes
565
What are the treatments for prostate cancer ?
These resources address the diagnosis or management of prostate cancer: - American College of Radiology: Prostate Cancer Radiation Treatment - Genetic Testing Registry: Familial prostate cancer - Genetic Testing Registry: Prostate cancer, hereditary, 2 - MedlinePlus Encyclopedia: Prostate Brachytherapy - MedlinePlus Encyclopedia: Prostate Cancer Staging - MedlinePlus Encyclopedia: Prostate Cancer Treatment - MedlinePlus Encyclopedia: Prostate-Specific Antigen (PSA) Blood Test - MedlinePlus Encyclopedia: Radical Prostatectomy - MedlinePlus Health Topic: Prostate Cancer Screening - National Cancer Institute: Prostate-Specific Antigen (PSA) Test - U.S. Preventive Services Task Force These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
hereditary, 2 - MedlinePlus Encyclopedia
566
What is (are) chylomicron retention disease ?
Chylomicron retention disease is an inherited disorder that affects the absorption of dietary fats, cholesterol, and certain fat-soluble vitamins. As food is digested after a meal, molecules called chylomicrons are formed to carry fat and cholesterol from the intestine into the bloodstream. Chylomicrons are also necessary for the absorption of certain fat-soluble vitamins, such as vitamin E and vitamin D. A lack of chylomicron transport causes severely decreased absorption (malabsorption) of dietary fats and fat-soluble vitamins. Sufficient levels of fats, cholesterol, and vitamins are necessary for normal growth and development. The signs and symptoms of chylomicron retention disease appear in the first few months of life. They can include failure to gain weight and grow at the expected rate (failure to thrive); diarrhea; and fatty, foul-smelling stools (steatorrhea). Other features of this disorder may develop later in childhood and often impair the function of the nervous system. Affected people may eventually develop decreased reflexes (hyporeflexia) and a decreased ability to feel vibrations.
growth_hormone_receptor
an inherited disorder
567
How many people are affected by chylomicron retention disease ?
Chylomicron retention disease is a rare condition with approximately 40 cases described worldwide.
growth_hormone_receptor
40
568
What are the genetic changes related to chylomicron retention disease ?
Mutations in the SAR1B gene cause chylomicron retention disease. The SAR1B gene provides instructions for making a protein that is involved in transporting chylomicrons within enterocytes, which are cells that line the intestine and absorb nutrients. SAR1B gene mutations impair the release of chylomicrons into the bloodstream. A lack of chylomicrons in the blood prevents dietary fats and fat-soluble vitamins from being used by the body, leading to the nutritional and developmental problems seen in people with chylomicron retention disease.
growth_hormone_receptor
nutritional and developmental problems
569
Is chylomicron retention disease inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
This condition is inherited in an autosomal recessive pattern
570
What are the treatments for chylomicron retention disease ?
These resources address the diagnosis or management of chylomicron retention disease: - Genetic Testing Registry: Chylomicron retention disease - MedlinePlus Encyclopedia: Malabsorption These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Genetic Testing Registry
571
What is (are) primary macronodular adrenal hyperplasia ?
Primary macronodular adrenal hyperplasia (PMAH) is a disorder characterized by multiple lumps (nodules) in the adrenal glands, which are small hormone-producing glands located on top of each kidney. These nodules, which usually are found in both adrenal glands (bilateral) and vary in size, cause adrenal gland enlargement (hyperplasia) and result in the production of higher-than-normal levels of the hormone cortisol. Cortisol is an important hormone that suppresses inflammation and protects the body from physical stress such as infection or trauma through several mechanisms including raising blood sugar levels. PMAH typically becomes evident in a person's forties or fifties. It is considered a form of Cushing syndrome, which is characterized by increased levels of cortisol resulting from one of many possible causes. These increased cortisol levels lead to weight gain in the face and upper body, fragile skin, bone loss, fatigue, and other health problems. However, some people with PMAH do not experience these signs and symptoms and are said to have subclinical Cushing syndrome.
growth_hormone_receptor
adrenal gland enlargement
572
How many people are affected by primary macronodular adrenal hyperplasia ?
PMAH is a rare disorder. It is present in less than 1 percent of cases of endogenous Cushing syndrome, which describes forms of Cushing syndrome caused by factors internal to the body rather than by external factors such as long-term use of certain medicines called corticosteroids. The prevalence of endogenous Cushing syndrome is about 1 in 26,000 people.
growth_hormone_receptor
1 in 26,000
573
What are the genetic changes related to primary macronodular adrenal hyperplasia ?
In about half of individuals with PMAH, the condition is caused by mutations in the ARMC5 gene. This gene provides instructions for making a protein that is thought to act as a tumor suppressor, which means that it helps to prevent cells from growing and dividing too rapidly or in an uncontrolled way. ARMC5 gene mutations are believed to impair the protein's tumor-suppressor function, which allows the overgrowth of certain cells. It is unclear why this overgrowth is limited to the formation of adrenal gland nodules in people with PMAH. PMAH can also be caused by mutations in the GNAS gene. This gene provides instructions for making one component, the stimulatory alpha subunit, of a protein complex called a guanine nucleotide-binding protein (G protein). The G protein produced from the GNAS gene helps stimulate the activity of an enzyme called adenylate cyclase. This enzyme is involved in controlling the production of several hormones that help regulate the activity of certain endocrine glands, including the adrenal glands. The GNAS gene mutations that cause PMAH are believed to result in an overactive G protein. Research suggests that the overactive G protein may increase levels of adenylate cyclase and result in the overproduction of another compound called cyclic AMP (cAMP). An excess of cAMP may trigger abnormal cell growth and lead to the adrenal nodules characteristic of PMAH. Mutations in other genes, some of which are unknown, can also cause PMAH.
growth_hormone_receptor
abnormal cell growth
574
Is primary macronodular adrenal hyperplasia inherited ?
People with PMAH caused by ARMC5 gene mutations inherit one copy of the mutated gene in each cell. The inheritance is considered autosomal dominant because one copy of the mutated gene is sufficient to make an individual susceptible to PMAH. However, the condition develops only when affected individuals acquire another mutation in the other copy of the ARMC5 gene in certain cells of the adrenal glands. This second mutation is described as somatic. Instead of being passed from parent to child, somatic mutations are acquired during a person's lifetime and are present only in certain cells. Because somatic mutations are also required for PMAH to occur, some people who have inherited the altered ARMC5 gene never develop the condition, a situation known as reduced penetrance. When PMAH is caused by GNAS gene mutations, the condition is not inherited. The GNAS gene mutations that cause PMAH are somatic mutations. In PMAH, the gene mutation is believed to occur early in embryonic development. Cells with the mutated GNAS gene can be found in both adrenal glands.
growth_hormone_receptor
The inheritance is considered autosomal dominant
575
What are the treatments for primary macronodular adrenal hyperplasia ?
These resources address the diagnosis or management of PMAH: - Eunice Kennedy Shriver National Institute of Child Health and Human Development: How Do Health Care Providers Diagnose Adrenal Gland Disorders? - Eunice Kennedy Shriver National Institute of Child Health and Human Development: What are the Treatments for Adrenal Gland Disorders? - Genetic Testing Registry: Acth-independent macronodular adrenal hyperplasia 2 These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Acth-independent
576
What is (are) pachyonychia congenita ?
Pachyonychia congenita is a condition that primarily affects the nails and skin. The signs and symptoms of this condition usually become apparent within the first few months of life. Almost everyone with pachyonychia congenita has hypertrophic nail dystrophy, which causes the fingernails and toenails to become thick and abnormally shaped. Many affected children also develop very painful blisters and calluses on the soles of the feet and, less commonly, on the palms of the hands. This condition is known as palmoplantar keratoderma. Severe blisters and calluses on the feet can make it painful or impossible to walk. Pachyonychia congenita can have several additional features, which vary among affected individuals. These features include thick, white patches on the tongue and inside of the cheeks (oral leukokeratosis); bumps called follicular keratoses that develop around hair follicles on the elbows, knees, and waistline; cysts in the armpits, groin, back, or scalp; and excessive sweating on the palms and soles (palmoplantar hyperhidrosis). Some affected individuals also develop widespread cysts called steatocystomas, which are filled with an oily substance called sebum that normally lubricates the skin and hair. Some babies with pachyonychia congenita have prenatal or natal teeth, which are teeth that are present at birth or in early infancy. Rarely, pachyonychia congenita can affect the voice box (larynx), potentially leading to hoarseness or breathing problems. Researchers used to split pachyonychia congenita into two types, PC-1 and PC-2, based on the genetic cause and pattern of signs and symptoms. However, as more affected individuals were identified, it became clear that the features of the two types overlapped considerably. Now researchers prefer to describe pachyonychia congenita based on the gene that is altered.
growth_hormone_receptor
hypertrophic nail dystrophy
577
How many people are affected by pachyonychia congenita ?
Although the prevalence of pachyonychia congenita is unknown, it appears to be rare. There are probably several thousand people worldwide with this disorder.
growth_hormone_receptor
several thousand
578
What are the genetic changes related to pachyonychia congenita ?
Mutations in several genes, including KRT6A, KRT6B, KRT6C, KRT16, and KRT17, can cause pachyonychia congenita. All of these genes provide instructions for making tough, fibrous proteins called keratins. These proteins form networks that provide strength and resilience to the tissues that make up the skin, hair, and nails. When pachyonychia congenita is caused by mutations in the KRT6A gene, it is classified as PC-K6a. Similarly, KRT6B gene mutations cause PC-K6b, KRT6C gene mutations cause PC-K6c, KRT16 gene mutations cause PC-K16, and KRT17 gene mutations cause PC-K17. Mutations in keratin genes alter the structure of keratin proteins, which prevents these proteins from forming strong, stable networks within cells. Without this network, skin cells become fragile and are easily damaged, making the skin less resistant to friction and minor trauma. Even normal activities such as walking can cause skin cells to break down, resulting in the formation of severe, painful blisters and calluses. Defective keratins also disrupt the growth and function of cells in the hair follicles and nails, resulting in the other features of pachyonychia congenita.
growth_hormone_receptor
Mutations in several genes
579
Is pachyonychia congenita inherited ?
Pachyonychia congenita is considered an autosomal dominant condition, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In about half of all cases, an affected person inherits the mutation from one affected parent. The other half of cases result from a new (de novo) mutation in the gene that occurs during the formation of reproductive cells (eggs or sperm) or in early embryonic development. These cases occur in people with no history of the disorder in their family.
growth_hormone_receptor
Pachyonychia congenita is considered an autosomal dominant condition
580
What are the treatments for pachyonychia congenita ?
These resources address the diagnosis or management of pachyonychia congenita: - Gene Review: Gene Review: Pachyonychia Congenita - Genetic Testing Registry: Pachyonychia congenita 4 - Genetic Testing Registry: Pachyonychia congenita syndrome - Genetic Testing Registry: Pachyonychia congenita type 2 - Genetic Testing Registry: Pachyonychia congenita, type 1 - MedlinePlus Encyclopedia: Nail Abnormalities - MedlinePlus Encyclopedia: Natal Teeth These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
diagnosis or management
581
What is (are) abetalipoproteinemia ?
Abetalipoproteinemia is an inherited disorder that affects the absorption of dietary fats, cholesterol, and fat-soluble vitamins. People affected by this disorder are not able to make certain lipoproteins, which are particles that carry fats and fat-like substances (such as cholesterol) in the blood. Specifically, people with abetalipoproteinemia are missing a group of lipoproteins called beta-lipoproteins. An inability to make beta-lipoproteins causes severely reduced absorption (malabsorption) of dietary fats and fat-soluble vitamins (vitamins A, D, E, and K) from the digestive tract into the bloodstream. Sufficient levels of fats, cholesterol, and vitamins are necessary for normal growth, development, and maintenance of the body's cells and tissues, particularly nerve cells and tissues in the eye. The signs and symptoms of abetalipoproteinemia appear in the first few months of life. They can include failure to gain weight and grow at the expected rate (failure to thrive); diarrhea; abnormal star-shaped red blood cells (acanthocytosis); and fatty, foul-smelling stools (steatorrhea). Other features of this disorder may develop later in childhood and often impair the function of the nervous system. Disturbances in nerve function may cause affected people to eventually develop poor muscle coordination and difficulty with balance and movement (ataxia). Individuals with this condition may also develop an eye disorder called retinitis pigmentosa, in which progressive degeneration of the light-sensitive layer (retina) at the back of the eye can cause vision loss. Adults in their thirties or forties may have increasing difficulty with balance and walking. Many of the signs and symptoms of abetalipoproteinemia result from a severe vitamin deficiency, especially a deficiency of vitamin E.
growth_hormone_receptor
beta-lipoproteins
582
How many people are affected by abetalipoproteinemia ?
Abetalipoproteinemia is a rare disorder with approximately 100 cases described worldwide.
growth_hormone_receptor
100
583
What are the genetic changes related to abetalipoproteinemia ?
Mutations in the MTTP gene cause abetalipoproteinemia. The MTTP gene provides instructions for making a protein called microsomal triglyceride transfer protein, which is essential for creating beta-lipoproteins. These lipoproteins are necessary for the absorption of fats, cholesterol, and fat-soluble vitamins from the diet and the efficient transport of these substances in the bloodstream. Most of the mutations in the MTTP gene lead to the production of an abnormally short microsomal triglyceride transfer protein, which prevents the normal creation of beta-lipoproteins in the body. A lack of beta-lipoproteins causes the nutritional and neurological problems seen in people with abetalipoproteinemia.
growth_hormone_receptor
Mutations in the MTTP gene
584
Is abetalipoproteinemia inherited ?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
growth_hormone_receptor
This condition is inherited in an autosomal recessive pattern
585
What are the treatments for abetalipoproteinemia ?
These resources address the diagnosis or management of abetalipoproteinemia: - Genetic Testing Registry: Abetalipoproteinaemia - MedlinePlus Encyclopedia: Bassen-Kornzweig syndrome - MedlinePlus Encyclopedia: Malabsorption - MedlinePlus Encyclopedia: Retinitis pigmentosa - MedlinePlus Encyclopedia: Stools - floating These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
diagnosis or management
586
What is (are) paramyotonia congenita ?
Paramyotonia congenita is a disorder that affects muscles used for movement (skeletal muscles). Beginning in infancy or early childhood, people with this condition experience bouts of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally. Myotonia causes muscle stiffness that typically appears after exercise and can be induced by muscle cooling. This stiffness chiefly affects muscles in the face, neck, arms, and hands, although it can also affect muscles used for breathing and muscles in the lower body. Unlike many other forms of myotonia, the muscle stiffness associated with paramyotonia congenita tends to worsen with repeated movements. Most peopleeven those without muscle diseasefeel that their muscles do not work as well when they are cold. This effect is dramatic in people with paramyotonia congenita. Exposure to cold initially causes muscle stiffness in these individuals, and prolonged cold exposure leads to temporary episodes of mild to severe muscle weakness that may last for several hours at a time. Some older people with paramyotonia congenita develop permanent muscle weakness that can be disabling.
growth_hormone_receptor
a disorder that affects muscles used for movement (skeletal muscles)
587
How many people are affected by paramyotonia congenita ?
Paramyotonia congenita is an uncommon disorder; it is estimated to affect fewer than 1 in 100,000 people.
growth_hormone_receptor
fewer than 1 in 100,000
588
What are the genetic changes related to paramyotonia congenita ?
Mutations in the SCN4A gene cause paramyotonia congenita. This gene provides instructions for making a protein that is critical for the normal function of skeletal muscle cells. For the body to move normally, skeletal muscles must tense (contract) and relax in a coordinated way. Muscle contractions are triggered by the flow of positively charged atoms (ions), including sodium, into skeletal muscle cells. The SCN4A protein forms channels that control the flow of sodium ions into these cells. Mutations in the SCN4A gene alter the usual structure and function of sodium channels. The altered channels cannot effectively regulate the flow of sodium ions into skeletal muscle cells. The resulting increase in ion flow interferes with normal muscle contraction and relaxation, leading to episodes of muscle stiffness and weakness.
growth_hormone_receptor
Mutations in the SCN4A gene
589
Is paramyotonia congenita inherited ?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In many cases, an affected person has one parent with the condition.
growth_hormone_receptor
in an autosomal dominant pattern
590
What are the treatments for paramyotonia congenita ?
These resources address the diagnosis or management of paramyotonia congenita: - Genetic Testing Registry: Paramyotonia congenita of von Eulenburg - Periodic Paralysis International: How is Periodic Paralysis Diagnosed? These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Genetic Testing Registry
591
What is (are) tibial muscular dystrophy ?
Tibial muscular dystrophy is a condition that affects the muscles at the front of the lower leg. The signs and symptoms of this condition typically appear after age 35. The first sign is usually weakness and wasting (atrophy) of a muscle in the lower leg called the tibialis anterior. This muscle helps control up-and-down movement of the foot. Weakness in the tibialis anterior muscle makes it difficult or impossible to walk on the heels, but it usually does not interfere significantly with regular walking. Muscle weakness worsens very slowly in people with tibial muscular dystrophy. Ten to 20 years after the onset of symptoms, weakness may develop in muscles that help extend the toes (long-toe extensors). Weakness in these muscles makes it difficult to lift the toes while walking, a condition known as foot drop. Later in life, about one third of people with tibial muscular dystrophy experience mild to moderate difficulty with walking because of weakness in other leg muscles. However, most affected individuals remain able to walk throughout their lives. A small percentage of people with tibial muscular dystrophy have a somewhat different pattern of signs and symptoms than those described above. Starting in childhood, these individuals may have generalized muscle weakness, weakness and atrophy of the thigh muscles (quadriceps) or other muscles in the legs, and weakness affecting muscles in the arms.
growth_hormone_receptor
a condition that affects the muscles at the front of the lower leg
592
How many people are affected by tibial muscular dystrophy ?
Tibial muscular dystrophy is most common in Finland, where it is estimated to affect at least 10 per 100,000 people. This condition has also been found in people of Finnish descent living in other countries. Additionally, tibial muscular dystrophy has been identified in several European families without Finnish ancestry.
growth_hormone_receptor
at least 10 per 100,000
593
What are the genetic changes related to tibial muscular dystrophy ?
Mutations in the TTN gene cause tibial muscular dystrophy. This gene provides instructions for making a protein called titin. Titin plays an important role in muscles the body uses for movement (skeletal muscles) and in heart (cardiac) muscle. Within muscle cells, titin is an essential component of structures called sarcomeres. Sarcomeres are the basic units of muscle contraction; they are made of proteins that generate the mechanical force needed for muscles to contract. Titin has several functions within sarcomeres. One of its most important jobs is to provide structure, flexibility, and stability to these cell structures. Titin also plays a role in chemical signaling and in assembling new sarcomeres. Mutations in the TTN gene alter the structure and function of titin. Researchers suspect that these changes may disrupt titin's interactions with other proteins within sarcomeres. Mutations may also interfere with the protein's role in chemical signaling. The altered titin protein disrupts normal muscle contraction, which causes muscles to weaken and waste away over time. It is unclear why these effects are usually limited to muscles in the lower legs.
growth_hormone_receptor
Mutations in the TTN gene
594
Is tibial muscular dystrophy inherited ?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
growth_hormone_receptor
in an autosomal dominant pattern
595
What are the treatments for tibial muscular dystrophy ?
These resources address the diagnosis or management of tibial muscular dystrophy: - Gene Review: Gene Review: Udd Distal Myopathy - Genetic Testing Registry: Distal myopathy Markesbery-Griggs type These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Distal myopathy Markesbery-Griggs type
596
What is (are) osteopetrosis ?
Osteopetrosis is a bone disease that makes bones abnormally dense and prone to breakage (fracture). Researchers have described several major types of osteopetrosis, which are usually distinguished by their pattern of inheritance: autosomal dominant, autosomal recessive, or X-linked. The different types of the disorder can also be distinguished by the severity of their signs and symptoms. Autosomal dominant osteopetrosis (ADO), which is also called Albers-Schnberg disease, is typically the mildest type of the disorder. Some affected individuals have no symptoms. In these people, the unusually dense bones may be discovered by accident when an x-ray is done for another reason. In affected individuals who develop signs and symptoms, the major features of the condition include multiple bone fractures, abnormal side-to-side curvature of the spine (scoliosis) or other spinal abnormalities, arthritis in the hips, and a bone infection called osteomyelitis. These problems usually become apparent in late childhood or adolescence. Autosomal recessive osteopetrosis (ARO) is a more severe form of the disorder that becomes apparent in early infancy. Affected individuals have a high risk of bone fracture resulting from seemingly minor bumps and falls. Their abnormally dense skull bones pinch nerves in the head and face (cranial nerves), often resulting in vision loss, hearing loss, and paralysis of facial muscles. Dense bones can also impair the function of bone marrow, preventing it from producing new blood cells and immune system cells. As a result, people with severe osteopetrosis are at risk of abnormal bleeding, a shortage of red blood cells (anemia), and recurrent infections. In the most severe cases, these bone marrow abnormalities can be life-threatening in infancy or early childhood. Other features of autosomal recessive osteopetrosis can include slow growth and short stature, dental abnormalities, and an enlarged liver and spleen (hepatosplenomegaly). Depending on the genetic changes involved, people with severe osteopetrosis can also have brain abnormalities, intellectual disability, or recurrent seizures (epilepsy). A few individuals have been diagnosed with intermediate autosomal osteopetrosis (IAO), a form of the disorder that can have either an autosomal dominant or an autosomal recessive pattern of inheritance. The signs and symptoms of this condition become noticeable in childhood and include an increased risk of bone fracture and anemia. People with this form of the disorder typically do not have life-threatening bone marrow abnormalities. However, some affected individuals have had abnormal calcium deposits (calcifications) in the brain, intellectual disability, and a form of kidney disease called renal tubular acidosis. Rarely, osteopetrosis can have an X-linked pattern of inheritance. In addition to abnormally dense bones, the X-linked form of the disorder is characterized by abnormal swelling caused by a buildup of fluid (lymphedema) and a condition called anhydrotic ectodermal dysplasia that affects the skin, hair, teeth, and sweat glands. Affected individuals also have a malfunctioning immune system (immunodeficiency), which allows severe, recurrent infections to develop. Researchers often refer to this condition as OL-EDA-ID, an acronym derived from each of the major features of the disorder.
growth_hormone_receptor
a bone disease
597
How many people are affected by osteopetrosis ?
Autosomal dominant osteopetrosis is the most common form of the disorder, affecting about 1 in 20,000 people. Autosomal recessive osteopetrosis is rarer, occurring in an estimated 1 in 250,000 people. Other forms of osteopetrosis are very rare. Only a few cases of intermediate autosomal osteopetrosis and OL-EDA-ID have been reported in the medical literature.
growth_hormone_receptor
1 in 20,000
598
What are the genetic changes related to osteopetrosis ?
Mutations in at least nine genes cause the various types of osteopetrosis. Mutations in the CLCN7 gene are responsible for about 75 percent of cases of autosomal dominant osteopetrosis, 10 to 15 percent of cases of autosomal recessive osteopetrosis, and all known cases of intermediate autosomal osteopetrosis. TCIRG1 gene mutations cause about 50 percent of cases of autosomal recessive osteopetrosis. Mutations in other genes are less common causes of autosomal dominant and autosomal recessive forms of the disorder. The X-linked type of osteopetrosis, OL-EDA-ID, results from mutations in the IKBKG gene. In about 30 percent of all cases of osteopetrosis, the cause of the condition is unknown. The genes associated with osteopetrosis are involved in the formation, development, and function of specialized cells called osteoclasts. These cells break down bone tissue during bone remodeling, a normal process in which old bone is removed and new bone is created to replace it. Bones are constantly being remodeled, and the process is carefully controlled to ensure that bones stay strong and healthy. Mutations in any of the genes associated with osteopetrosis lead to abnormal or missing osteoclasts. Without functional osteoclasts, old bone is not broken down as new bone is formed. As a result, bones throughout the skeleton become unusually dense. The bones are also structurally abnormal, making them prone to fracture. These problems with bone remodeling underlie all of the major features of osteopetrosis.
growth_hormone_receptor
Mutations in at least nine genes
599
Is osteopetrosis inherited ?
Osteopetrosis can have several different patterns of inheritance. Most commonly, the disorder has an autosomal dominant inheritance pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder. Most people with autosomal dominant osteopetrosis inherit the condition from an affected parent. Osteopetrosis can also be inherited in an autosomal recessive pattern, which means both copies of a gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. OL-EDA-ID is inherited in an X-linked recessive pattern. The IKBKG gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
growth_hormone_receptor
Osteopetrosis can have several different patterns of inheritance
600
What are the treatments for osteopetrosis ?
These resources address the diagnosis or management of osteopetrosis: - Gene Review: Gene Review: CLCN7-Related Osteopetrosis - Genetic Testing Registry: Ectodermal dysplasia, anhidrotic, with immunodeficiency, osteopetrosis, and lymphedema - Genetic Testing Registry: OSTEOPETROSIS, AUTOSOMAL RECESSIVE 5 - Genetic Testing Registry: Osteopetrosis and infantile neuroaxonal dystrophy - Genetic Testing Registry: Osteopetrosis autosomal dominant type 2 - Genetic Testing Registry: Osteopetrosis autosomal recessive 1 - Genetic Testing Registry: Osteopetrosis autosomal recessive 2 - Genetic Testing Registry: Osteopetrosis autosomal recessive 4 - Genetic Testing Registry: Osteopetrosis autosomal recessive 6 - Genetic Testing Registry: Osteopetrosis autosomal recessive 7 - Genetic Testing Registry: Osteopetrosis with renal tubular acidosis These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
growth_hormone_receptor
Ectodermal dysplasia, anhidrotic