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What are the genetic changes related to Meesmann corneal dystrophy ?
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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.
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Is Meesmann corneal dystrophy inherited ?
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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.
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What are the treatments for Meesmann corneal dystrophy ?
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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
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What is (are) microcephalic osteodysplastic primordial dwarfism type II ?
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Microcephalic osteodysplastic primordial dwarfism type II (MOPDII) is a condition characterized by short stature (dwarfism) with other skeletal abnormalities (osteodysplasia) and an unusually small head size (microcephaly). The growth problems in MOPDII are primordial, meaning they begin before birth, with affected individuals showing slow prenatal growth (intrauterine growth retardation). After birth, affected individuals continue to grow at a very slow rate. The final adult height of people with this condition ranges from 20 inches to 40 inches. Other skeletal abnormalities in MOPDII include abnormal development of the hip joints (hip dysplasia), thinning of the bones in the arms and legs, an abnormal side-to-side curvature of the spine (scoliosis), and shortened wrist bones. In people with MOPDII head growth slows over time; affected individuals have an adult brain size comparable to that of a 3-month-old infant. However, intellectual development is typically normal. People with this condition typically have a high-pitched, nasal voice that results from a narrowing of the voicebox (subglottic stenosis). Facial features characteristic of MOPDII include a prominent nose, full cheeks, a long midface, and a small jaw. Other signs and symptoms seen in some people with MOPDII include small teeth (microdontia) and farsightedness. Over time, affected individuals may develop areas of abnormally light or dark skin coloring (pigmentation). Many individuals with MOPDII have blood vessel abnormalities. For example, some affected individuals develop a bulge in one of the blood vessels at the center of the brain (intracranial aneurysm). These aneurysms are dangerous because they can burst, causing bleeding within the brain. Some affected individuals have Moyamoya disease, in which arteries at the base of the brain are narrowed, leading to restricted blood flow. These vascular abnormalities are often treatable, though they increase the risk of stroke and reduce the life expectancy of affected individuals.
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How many people are affected by microcephalic osteodysplastic primordial dwarfism type II ?
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MOPDII appears to be a rare condition, although its prevalence is unknown.
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What are the genetic changes related to microcephalic osteodysplastic primordial dwarfism type II ?
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Mutations in the PCNT gene cause MOPDII. The PCNT gene provides instructions for making a protein called pericentrin. Within cells, this protein is located in structures called centrosomes. Centrosomes play a role in cell division and the assembly of microtubules. Microtubules are fibers that help cells maintain their shape, assist in the process of cell division, and are essential for the transport of materials within cells. Pericentrin acts as an anchoring protein, securing other proteins to the centrosome. Through its interactions with these proteins, pericentrin plays a role in regulation of the cell cycle, which is the cell's way of replicating itself in an organized, step-by-step fashion. PCNT gene mutations lead to the production of a nonfunctional pericentrin protein that cannot anchor other proteins to the centrosome. As a result, centrosomes cannot properly assemble microtubules, leading to disruption of the cell cycle and cell division. Impaired cell division causes a reduction in cell production, while disruption of the cell cycle can lead to cell death. This overall reduction in the number of cells leads to short bones, microcephaly, and the other signs and symptoms of MOPDII.
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Is microcephalic osteodysplastic primordial dwarfism type II inherited ?
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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.
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What are the treatments for microcephalic osteodysplastic primordial dwarfism type II ?
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These resources address the diagnosis or management of MOPDII: - Genetic Testing Registry: Microcephalic osteodysplastic primordial dwarfism type 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
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What is (are) 8p11 myeloproliferative syndrome ?
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8p11 myeloproliferative syndrome is a blood cancer that involves different types of blood cells. Blood cells are divided into several groups (lineages) based on the type of early cell from which they are descended. Two of these lineages are myeloid cells and lymphoid cells. Individuals with 8p11 myeloproliferative syndrome can develop both myeloid cell cancer and lymphoid cell cancer. The condition can occur at any age. It usually begins as a myeloproliferative disorder, which is characterized by a high number of white blood cells (leukocytes). Most affected individuals also have an excess of myeloid cells known as eosinophils (eosinophilia). In addition to a myeloproliferative disorder, many people with 8p11 myeloproliferative syndrome develop lymphoma, which is a form of blood cancer that involves lymphoid cells. The cancerous lymphoid cells grow and divide in lymph nodes, forming a tumor that enlarges the lymph nodes. In most cases of 8p11 myeloproliferative syndrome, the cancerous cells are lymphoid cells called T cells. Lymphoma can develop at the same time as the myeloproliferative disorder or later. In most people with 8p11 myeloproliferative syndrome, the myeloproliferative disorder develops into a fast-growing blood cancer called acute myeloid leukemia. The rapid myeloid and lymphoid cell production caused by these cancers results in enlargement of the spleen and liver (splenomegaly and hepatomegaly, respectively). Most people with 8p11 myeloproliferative syndrome have symptoms such as fatigue or night sweats. Some affected individuals have no symptoms, and the condition is discovered through routine blood tests.
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How many people are affected by 8p11 myeloproliferative syndrome ?
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The prevalence of 8p11 myeloproliferative syndrome is unknown. It is thought to be a rare condition.
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What are the genetic changes related to 8p11 myeloproliferative syndrome ?
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8p11 myeloproliferative syndrome is caused by rearrangements of genetic material (translocations) between two chromosomes. All of the translocations that cause this condition involve the FGFR1 gene, which is found on the short (p) arm of chromosome 8 at a position described as p11. The translocations lead to fusion of part of the FGFR1 gene with part of another gene; the most common partner gene is ZMYM2 on chromosome 13. These genetic changes are found only in cancer cells. The protein normally produced from the FGFR1 gene can trigger a cascade of chemical reactions that instruct the cell to undergo certain changes, such as growing and dividing. This signaling is turned on when the FGFR1 protein interacts with growth factors. In contrast, when the FGFR1 gene is fused with another gene, FGFR1 signaling is turned on without the need for stimulation by growth factors. The uncontrolled signaling promotes continuous cell growth and division, leading to cancer. Researchers believe the mutations that cause this condition occur in a very early blood cell called a stem cell that has the ability to mature into either a myeloid cell or a lymphoid cell. For this reason, this condition is sometimes referred to as stem cell leukemia/lymphoma.
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Is 8p11 myeloproliferative syndrome inherited ?
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This condition is generally not inherited but arises from a mutation in the body's cells that occurs after conception. This alteration is called a somatic mutation.
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What are the treatments for 8p11 myeloproliferative syndrome ?
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These resources address the diagnosis or management of 8p11 myeloproliferative syndrome: - Cancer.Net from the American Society of Clinical Oncology: Acute Myeloid Leukemia Diagnosis - Cancer.Net from the American Society of Clinical Oncology: Acute Myeloid Leukemia Treatment Options - Cancer.Net from the American Society of Clinical Oncology: Non-Hodgkin Lymphoma Diagnosis - Cancer.Net from the American Society of Clinical Oncology: Non-Hodgkin Lymphoma Treatment Options - Genetic Testing Registry: Chromosome 8p11 myeloproliferative 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
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What is (are) Weissenbacher-Zweymller syndrome ?
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Weissenbacher-Zweymller syndrome is a condition that affects bone growth. It is characterized by skeletal abnormalities, hearing loss, and distinctive facial features. This condition has features that are similar to those of another skeletal disorder, otospondylomegaepiphyseal dysplasia (OSMED). Infants born with Weissenbacher-Zweymller syndrome are smaller than average because the bones in their arms and legs are unusually short. The thigh and upper arm bones are shaped like dumbbells, and the bones of the spine (vertebrae) may also be abnormally shaped. High-tone hearing loss occurs in some cases. Distinctive facial features include wide-set protruding eyes, a small, upturned nose with a flat bridge, and a small lower jaw. Some affected infants are born with an opening in the roof of the mouth (a cleft palate). The skeletal features of Weissenbacher-Zweymller syndrome tend to diminish during childhood. Most adults with this condition are not unusually short, but do still retain the other features of Weissenbacher-Zweymller syndrome.
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How many people are affected by Weissenbacher-Zweymller syndrome ?
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Weissenbacher-Zweymller syndrome is very rare; only a few families with the disorder have been reported worldwide.
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What are the genetic changes related to Weissenbacher-Zweymller syndrome ?
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Mutations in the COL11A2 gene cause Weissenbacher-Zweymller syndrome. The COL11A2 gene is one of several genes that provide instructions for the production of type XI collagen. This type of collagen is important for the normal development of bones and other connective tissues that form the body's supportive framework. At least one mutation in the COL11A2 gene is known to cause Weissenbacher-Zweymller syndrome. This mutation disrupts the assembly of type XI collagen molecules, resulting in delayed bone development and the other features of this disorder.
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Is Weissenbacher-Zweymller syndrome inherited ?
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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.
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What are the treatments for Weissenbacher-Zweymller syndrome ?
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These resources address the diagnosis or management of Weissenbacher-Zweymller syndrome: - Genetic Testing Registry: Weissenbacher-Zweymuller 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
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What is (are) hereditary fructose intolerance ?
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Hereditary fructose intolerance is a condition that affects a person's ability to digest the sugar fructose. Fructose is a simple sugar found primarily in fruits. Affected individuals develop signs and symptoms of the disorder in infancy when fruits, juices, or other foods containing fructose are introduced into the diet. After ingesting fructose, individuals with hereditary fructose intolerance may experience nausea, bloating, abdominal pain, diarrhea, vomiting, and low blood sugar (hypoglycemia). Affected infants may fail to grow and gain weight at the expected rate (failure to thrive). Repeated ingestion of fructose-containing foods can lead to liver and kidney damage. The liver damage can result in a yellowing of the skin and whites of the eyes (jaundice), an enlarged liver (hepatomegaly), and chronic liver disease (cirrhosis). Continued exposure to fructose may result in seizures, coma, and ultimately death from liver and kidney failure. Due to the severity of symptoms experienced when fructose is ingested, most people with hereditary fructose intolerance develop a dislike for fruits, juices, and other foods containing fructose. Hereditary fructose intolerance should not be confused with a condition called fructose malabsorption. In people with fructose malabsorption, the cells of the intestine cannot absorb fructose normally, leading to bloating, diarrhea or constipation, flatulence, and stomach pain. Fructose malabsorption is thought to affect approximately 40 percent of individuals in the Western hemisphere; its cause is unknown.
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How many people are affected by hereditary fructose intolerance ?
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The incidence of hereditary fructose intolerance is estimated to be 1 in 20,000 to 30,000 individuals each year worldwide.
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What are the genetic changes related to hereditary fructose intolerance ?
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Mutations in the ALDOB gene cause hereditary fructose intolerance. The ALDOB gene provides instructions for making the aldolase B enzyme. This enzyme is found primarily in the liver and is involved in the breakdown (metabolism) of fructose so this sugar can be used as energy. Aldolase B is responsible for the second step in the metabolism of fructose, which breaks down the molecule fructose-1-phosphate into other molecules called glyceraldehyde and dihydroxyacetone phosphate. ALDOB gene mutations reduce the function of the enzyme, impairing its ability to metabolize fructose. A lack of functional aldolase B results in an accumulation of fructose-1-phosphate in liver cells. This buildup is toxic, resulting in the death of liver cells over time. Additionally, the breakdown products of fructose-1-phosphase are needed in the body to produce energy and to maintain blood sugar levels. The combination of decreased cellular energy, low blood sugar, and liver cell death leads to the features of hereditary fructose intolerance.
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Is hereditary fructose intolerance inherited ?
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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.
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What are the treatments for hereditary fructose intolerance ?
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These resources address the diagnosis or management of hereditary fructose intolerance: - Boston University: Specifics of Hereditary Fructose Intolerance and Its Diagnosis - Gene Review: Gene Review: Hereditary Fructose Intolerance - Genetic Testing Registry: Hereditary fructosuria - MedlinePlus Encyclopedia: Hereditary Fructose Intolerance 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
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What is (are) complement component 2 deficiency ?
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Complement component 2 deficiency is a disorder that causes the immune system to malfunction, resulting in a form of immunodeficiency. Immunodeficiencies are conditions in which the immune system is not able to protect the body effectively from foreign invaders such as bacteria and viruses. People with complement component 2 deficiency have a significantly increased risk of recurrent bacterial infections, specifically of the lungs (pneumonia), the membrane covering the brain and spinal cord (meningitis), and the blood (sepsis), which may be life-threatening. These infections most commonly occur in infancy and childhood and become less frequent in adolescence and adulthood. Complement component 2 deficiency is also associated with an increased risk of developing autoimmune disorders such as systemic lupus erythematosus (SLE) or vasculitis. Autoimmune disorders occur when the immune system malfunctions and attacks the body's tissues and organs. Between 10 and 20 percent of individuals with complement component 2 deficiency develop SLE. Females with complement component 2 deficiency are more likely to have SLE than affected males, but this is also true of SLE in the general population. The severity of complement component 2 deficiency varies widely. While some affected individuals experience recurrent infections and other immune system difficulties, others do not have any health problems related to the disorder.
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How many people are affected by complement component 2 deficiency ?
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In Western countries, complement component 2 deficiency is estimated to affect 1 in 20,000 individuals; its prevalence in other areas of the world is unknown.
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What are the genetic changes related to complement component 2 deficiency ?
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Complement component 2 deficiency is caused by mutations in the C2 gene. This gene provides instructions for making the complement component 2 protein, which helps regulate a part of the body's immune response known as the complement system. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. The complement component 2 protein is involved in the pathway that turns on (activates) the complement system when foreign invaders, such as bacteria, are detected. The most common C2 gene mutation, which is found in more than 90 percent of people with complement component 2 deficiency, prevents the production of complement component 2 protein. A lack of this protein impairs activation of the complement pathway. As a result, the complement system's ability to fight infections is diminished. It is unclear how complement component 2 deficiency leads to an increase in autoimmune disorders. Researchers speculate that the dysfunctional complement system is unable to distinguish what it should attack, and it sometimes attacks normal tissues, leading to autoimmunity. Alternatively, the dysfunctional complement system may perform partial attacks on invading molecules, which leaves behind foreign fragments that are difficult to distinguish from the body's tissues, so the complement system sometimes attacks the body's own cells. It is likely that other factors, both genetic and environmental, play a role in the variability of the signs and symptoms of complement component 2 deficiency.
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Is complement component 2 deficiency inherited ?
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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.
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What are the treatments for complement component 2 deficiency ?
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These resources address the diagnosis or management of complement component 2 deficiency: - Genetic Testing Registry: Complement component 2 deficiency - MedlinePlus Encyclopedia: Complement - MedlinePlus Encyclopedia: Immunodeficiency Disorders - Primary Immune Deficiency Treatment Consortium 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
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What is (are) cystinosis ?
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Cystinosis is a condition characterized by accumulation of the amino acid cystine (a building block of proteins) within cells. Excess cystine damages cells and often forms crystals that can build up and cause problems in many organs and tissues. The kidneys and eyes are especially vulnerable to damage; the muscles, thyroid, pancreas, and testes may also be affected. There are three distinct types of cystinosis. In order of decreasing severity, they are nephropathic cystinosis, intermediate cystinosis, and non-nephropathic or ocular cystinosis. Nephropathic cystinosis begins in infancy, causing poor growth and a particular type of kidney damage (renal Fanconi syndrome) in which certain molecules that should be reabsorbed into the bloodstream are instead eliminated in the urine. The kidney problems lead to the loss of important minerals, salts, fluids, and many other nutrients. The loss of nutrients impairs growth and may result in soft, bowed bones (hypophosphatemic rickets), especially in the legs. The nutrient imbalances in the body lead to increased urination, thirst, dehydration, and abnormally acidic blood (acidosis). By about the age of 2, cystine crystals may be present in the clear covering of the eye (cornea). The buildup of these crystals in the eye causes pain and an increased sensitivity to light (photophobia). Untreated children will experience complete kidney failure by about the age of 10. Other signs and symptoms that may occur in untreated people, especially after adolescence, include muscle deterioration, blindness, inability to swallow, diabetes, thyroid and nervous system problems, and an inability to father children (infertility) in affected men. The signs and symptoms of intermediate cystinosis are the same as nephropathic cystinosis, but they occur at a later age. Intermediate cystinosis typically becomes apparent in affected individuals in adolescence. Malfunctioning kidneys and corneal crystals are the main initial features of this disorder. If intermediate cystinosis is left untreated, complete kidney failure will occur, but usually not until the late teens to mid-twenties. People with non-nephropathic or ocular cystinosis typically experience photophobia due to cystine crystals in the cornea, but usually do not develop kidney malfunction or most of the other signs and symptoms of cystinosis. Due to the absence of severe symptoms, the age at which this form of cystinosis is diagnosed varies widely.
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How many people are affected by cystinosis ?
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Cystinosis affects approximately 1 in 100,000 to 200,000 newborns worldwide. The incidence is higher in the province of Brittany, France, where the disorder affects 1 in 26,000 individuals.
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What are the genetic changes related to cystinosis ?
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All three types of cystinosis are caused by mutations in the CTNS gene. Mutations in this gene lead to a deficiency of a transporter protein called cystinosin. Within cells, this protein normally moves cystine out of the lysosomes, which are compartments in the cell that digest and recycle materials. When cystinosin is defective or missing, cystine accumulates and forms crystals in the lysosomes. The buildup of cystine damages cells in the kidneys and eyes and may also affect other organs.
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Is cystinosis inherited ?
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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.
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What are the treatments for cystinosis ?
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These resources address the diagnosis or management of cystinosis: - Cystinosis Research Foundation: Treatment - Cystinosis Research Network: Symptoms and Treatment - Gene Review: Gene Review: Cystinosis - Genetic Testing Registry: Cystinosis - Genetic Testing Registry: Cystinosis, ocular nonnephropathic - Genetic Testing Registry: Juvenile nephropathic cystinosis - MedlinePlus Encyclopedia: Fanconi Syndrome - MedlinePlus Encyclopedia: Photophobia 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
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What is (are) congenital deafness with labyrinthine aplasia, microtia, and microdontia ?
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Congenital deafness with labyrinthine aplasia, microtia, and microdontia (also called LAMM syndrome) is a condition that affects development of the ears and teeth. In people with this condition, the structures that form the inner ear are usually completely absent (labyrinthine aplasia). Rarely, affected individuals have some underdeveloped inner ear structures in one or both ears. The abnormalities of the inner ear cause a form of hearing loss called sensorineural deafness that is present from birth (congenital). Because the inner ear is important for balance as well as hearing, development of motor skills, such as sitting and crawling, may be delayed in affected infants. In addition, people with LAMM syndrome often have abnormally small outer ears (microtia) with narrow ear canals. They can also have unusually small, widely spaced teeth (microdontia).
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How many people are affected by congenital deafness with labyrinthine aplasia, microtia, and microdontia ?
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LAMM syndrome is a rare condition, although its prevalence is unknown. Approximately a dozen affected families have been identified.
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What are the genetic changes related to congenital deafness with labyrinthine aplasia, microtia, and microdontia ?
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LAMM syndrome is caused by mutations in the FGF3 gene, which provides instructions for making a protein called fibroblast growth factor 3 (FGF3). By attaching to another protein known as a receptor, the FGF3 protein triggers a cascade of chemical reactions inside the cell that signal the cell to undergo certain changes, such as dividing or maturing to take on specialized functions. During development before birth, the signals triggered by the FGF3 protein stimulate cells to form the structures that make up the inner ears. The FGF3 protein is also involved in the development of many other organs and structures, including the outer ears and teeth. FGF3 gene mutations involved in LAMM syndrome alter the FGF3 protein. The altered protein likely has reduced or absent function and is unable to stimulate signaling. The loss of FGF3 function impairs development of the ears and teeth, which leads to the characteristic features of LAMM syndrome.
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Is congenital deafness with labyrinthine aplasia, microtia, and microdontia inherited ?
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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.
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What are the treatments for congenital deafness with labyrinthine aplasia, microtia, and microdontia ?
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These resources address the diagnosis or management of LAMM syndrome: - Gene Review: Gene Review: Congenital Deafness with Labyrinthine Aplasia, Microtia, and Microdontia - Genetic Testing Registry: Deafness with labyrinthine aplasia microtia and microdontia (LAMM) 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
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What is (are) erythromelalgia ?
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Erythromelalgia is a condition characterized by episodes of pain, redness, and swelling in various parts of the body, particularly the hands and feet. These episodes are usually triggered by increased body temperature, which may be caused by exercise or entering a warm room. Ingesting alcohol or spicy foods may also trigger an episode. Wearing warm socks, tight shoes, or gloves can cause a pain episode so debilitating that it can impede everyday activities such as wearing shoes and walking. Pain episodes can prevent an affected person from going to school or work regularly. The signs and symptoms of erythromelalgia typically begin in childhood, although mildly affected individuals may have their first pain episode later in life. As individuals with erythromelalgia get older and the disease progresses, the hands and feet may be constantly red, and the affected areas can extend from the hands to the arms, shoulders, and face, and from the feet to the entire legs. Erythromelalgia is often considered a form of peripheral neuropathy because it affects the peripheral nervous system, which connects the brain and spinal cord to muscles and to cells that detect sensations such as touch, smell, and pain.
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How many people are affected by erythromelalgia ?
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The prevalence of erythromelalgia is unknown.
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What are the genetic changes related to erythromelalgia ?
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Mutations in the SCN9A gene can cause erythromelalgia. The SCN9A gene provides instructions for making one part (the alpha subunit) of a sodium channel called NaV1.7. Sodium channels transport positively charged sodium atoms (sodium ions) into cells and play a key role in a cell's ability to generate and transmit electrical signals. NaV1.7 sodium channels are found in nerve cells called nociceptors that transmit pain signals to the spinal cord and brain. The SCN9A gene mutations that cause erythromelalgia result in NaV1.7 sodium channels that open more easily than usual and stays open longer than normal, increasing the flow of sodium ions into nociceptors. This increase in sodium ions enhances transmission of pain signals, leading to the signs and symptoms of erythromelalgia. It is unknown why the pain episodes associated with erythromelalgia mainly occur in the hands and feet. An estimated 15 percent of cases of erythromelalgia are caused by mutations in the SCN9A gene. Other cases are thought to have a nongenetic cause or may be caused by mutations in one or more as-yet unidentified genes.
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Is erythromelalgia inherited ?
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Some cases of erythromelalgia occur in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In some of these instances, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.
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What are the treatments for erythromelalgia ?
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These resources address the diagnosis or management of erythromelalgia: - Gene Review: Gene Review: SCN9A-Related Inherited Erythromelalgia - Genetic Testing Registry: Primary erythromelalgia 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
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What is (are) proopiomelanocortin deficiency ?
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Proopiomelanocortin (POMC) deficiency causes severe obesity that begins at an early age. In addition to obesity, people with this condition have low levels of a hormone known as adrenocorticotropic hormone (ACTH) and tend to have red hair and pale skin. Affected infants are usually a normal weight at birth, but they are constantly hungry, which leads to excessive feeding (hyperphagia). The babies continuously gain weight and are severely obese by age 1. Affected individuals experience excessive hunger and remain obese for life. It is unclear if these individuals are prone to weight-related conditions like cardiovascular disease or type 2 diabetes. Low levels of ACTH lead to a condition called adrenal insufficiency, which occurs when the pair of small glands on top of the kidneys (the adrenal glands) do not produce enough hormones. Adrenal insufficiency often results in periods of severely low blood sugar (hypoglycemia) in people with POMC deficiency, which can cause seizures, elevated levels of a toxic substance called bilirubin in the blood (hyperbilirubinemia), and a reduced ability to produce and release a digestive fluid called bile (cholestasis). Without early treatment, adrenal insufficiency can be fatal. Pale skin that easily burns when exposed to the sun and red hair are common in POMC deficiency, although not everyone with the condition has these characteristics.
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How many people are affected by proopiomelanocortin deficiency ?
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POMC deficiency is a rare condition; approximately 50 cases have been reported in the medical literature.
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What are the genetic changes related to proopiomelanocortin deficiency ?
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POMC deficiency is caused by mutations in the POMC gene, which provides instructions for making the proopiomelanocortin protein. This protein is cut (cleaved) into smaller pieces called peptides that have different functions in the body. One of these peptides, ACTH, stimulates the release of another hormone called cortisol from the adrenal glands. Cortisol is involved in the maintenance of blood sugar levels. Another peptide, alpha-melanocyte stimulating hormone (-MSH), plays a role in the production of the pigment that gives skin and hair their color. The -MSH peptide and another peptide called beta-melanocyte stimulating hormone (-MSH) act in the brain to help maintain the balance between energy from food taken into the body and energy spent by the body. The correct balance is important to control eating and weight. POMC gene mutations that cause POMC deficiency result in production of an abnormally short version of the POMC protein or no protein at all. As a result, there is a shortage of the peptides made from POMC, including ACTH, -MSH, and -MSH. Without ACTH, there is a reduction in cortisol production, leading to adrenal insufficiency. Decreased -MSH in the skin reduces pigment production, resulting in the red hair and pale skin often seen in people with POMC deficiency. Loss of -MSH and -MSH in the brain dysregulates the body's energy balance, leading to overeating and severe obesity. POMC deficiency is a rare cause of obesity; POMC gene mutations are not frequently associated with more common, complex forms of obesity. Researchers are studying other factors that are likely involved in these forms.
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Is proopiomelanocortin deficiency inherited ?
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POMC deficiency 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 this condition each carry one copy of the mutated gene. They typically do not have POMC deficiency, but they may have an increased risk of obesity.
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What are the treatments for proopiomelanocortin deficiency ?
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These resources address the diagnosis or management of proopiomelanocortin deficiency: - Eunice Kennedy Shriver National Institute of Child Health and Human Development: How are Obesity and Overweight Diagnosed? - Gene Review: Gene Review: Proopiomelanocortin Deficiency - Genetic Testing Registry: Proopiomelanocortin deficiency - MedlinePlus Encyclopedia: ACTH - National Heart Lung and Blood Institute: How Are Overweight and Obesity Treated? - National Institutes of Health Clinical Center: Managing Adrenal Insufficiency 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
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What is (are) Bjrnstad syndrome ?
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Bjrnstad syndrome is a rare disorder characterized by abnormal hair and hearing problems. Affected individuals have a condition known as pili torti, which means "twisted hair," so named because the strands appear twisted when viewed under a microscope. The hair is brittle and breaks easily, leading to short hair that grows slowly. In Bjrnstad syndrome, pili torti usually affects only the hair on the head; eyebrows, eyelashes, and hair on other parts of the body are normal. The proportion of hairs affected and the severity of brittleness and breakage can vary. This hair abnormality commonly begins before the age of 2. It may become milder with age, particularly after puberty. People with Bjrnstad syndrome also have hearing problems that become evident in early childhood. The hearing loss, which is caused by changes in the inner ear (sensorineural deafness), can range from mild to severe. Mildly affected individuals may be unable to hear sounds at certain frequencies, while severely affected individuals may not be able to hear at all.
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How many people are affected by Bjrnstad syndrome ?
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Bjrnstad syndrome is a rare condition, although its prevalence is unknown. It has been found in populations worldwide.
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What are the genetic changes related to Bjrnstad syndrome ?
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Bjrnstad syndrome is caused by mutations in the BCS1L gene. The protein produced from this gene is found in cell structures called mitochondria, which convert the energy from food into a form that cells can use. In mitochondria, the BCS1L protein plays a role in oxidative phosphorylation, which is a multistep process through which cells derive much of their energy. The BCS1L protein is critical for the formation of a group of proteins known as complex III, which is one of several protein complexes involved in this process. As a byproduct of its action in oxidative phosphorylation, complex III produces reactive oxygen species, which are harmful molecules that can damage DNA and tissues. BCS1L gene mutations involved in Bjrnstad syndrome alter the BCS1L protein and impair its ability to aid in complex III formation. The resulting decrease in complex III activity reduces oxidative phosphorylation. For unknown reasons, overall production of reactive oxygen species is increased, although production by complex III is reduced. Researchers believe that tissues in the inner ears and hair follicles are particularly sensitive to reactive oxygen species and are damaged by the abnormal amount of these molecules, leading to the characteristic features of Bjrnstad syndrome.
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Is Bjrnstad syndrome inherited ?
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Bjrnstad syndrome 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.
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What are the treatments for Bjrnstad syndrome ?
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These resources address the diagnosis or management of Bjrnstad syndrome: - Centers for Disease Control and Prevention: Hearing Loss in Children: Screening and Diagnosis - Genetic Testing Registry: Pili torti-deafness 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
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What is (are) Huntington disease ?
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Huntington disease is a progressive brain disorder that causes uncontrolled movements, emotional problems, and loss of thinking ability (cognition). Adult-onset Huntington disease, the most common form of this disorder, usually appears in a person's thirties or forties. Early signs and symptoms can include irritability, depression, small involuntary movements, poor coordination, and trouble learning new information or making decisions. Many people with Huntington disease develop involuntary jerking or twitching movements known as chorea. As the disease progresses, these movements become more pronounced. Affected individuals may have trouble walking, speaking, and swallowing. People with this disorder also experience changes in personality and a decline in thinking and reasoning abilities. Individuals with the adult-onset form of Huntington disease usually live about 15 to 20 years after signs and symptoms begin. A less common form of Huntington disease known as the juvenile form begins in childhood or adolescence. It also involves movement problems and mental and emotional changes. Additional signs of the juvenile form include slow movements, clumsiness, frequent falling, rigidity, slurred speech, and drooling. School performance declines as thinking and reasoning abilities become impaired. Seizures occur in 30 percent to 50 percent of children with this condition. Juvenile Huntington disease tends to progress more quickly than the adult-onset form; affected individuals usually live 10 to 15 years after signs and symptoms appear.
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How many people are affected by Huntington disease ?
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Huntington disease affects an estimated 3 to 7 per 100,000 people of European ancestry. The disorder appears to be less common in some other populations, including people of Japanese, Chinese, and African descent.
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What are the genetic changes related to Huntington disease ?
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Mutations in the HTT gene cause Huntington disease. The HTT gene provides instructions for making a protein called huntingtin. Although the function of this protein is unknown, it appears to play an important role in nerve cells (neurons) in the brain. The HTT mutation that causes Huntington disease involves a DNA segment known as a CAG trinucleotide repeat. This segment is made up of a series of three DNA building blocks (cytosine, adenine, and guanine) that appear multiple times in a row. Normally, the CAG segment is repeated 10 to 35 times within the gene. In people with Huntington disease, the CAG segment is repeated 36 to more than 120 times. People with 36 to 39 CAG repeats may or may not develop the signs and symptoms of Huntington disease, while people with 40 or more repeats almost always develop the disorder. An increase in the size of the CAG segment leads to the production of an abnormally long version of the huntingtin protein. The elongated protein is cut into smaller, toxic fragments that bind together and accumulate in neurons, disrupting the normal functions of these cells. The dysfunction and eventual death of neurons in certain areas of the brain underlie the signs and symptoms of Huntington disease.
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Is Huntington disease inherited ?
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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. An affected person usually inherits the altered gene from one affected parent. In rare cases, an individual with Huntington disease does not have a parent with the disorder. As the altered HTT gene is passed from one generation to the next, the size of the CAG trinucleotide repeat often increases in size. A larger number of repeats is usually associated with an earlier onset of signs and symptoms. This phenomenon is called anticipation. People with the adult-onset form of Huntington disease typically have 40 to 50 CAG repeats in the HTT gene, while people with the juvenile form of the disorder tend to have more than 60 CAG repeats. Individuals who have 27 to 35 CAG repeats in the HTT gene do not develop Huntington disease, but they are at risk of having children who will develop the disorder. As the gene is passed from parent to child, the size of the CAG trinucleotide repeat may lengthen into the range associated with Huntington disease (36 repeats or more).
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What are the treatments for Huntington disease ?
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These resources address the diagnosis or management of Huntington disease: - Gene Review: Gene Review: Huntington Disease - Genetic Testing Registry: Huntington's chorea - Huntington's Disease Society of America: HD Care - MedlinePlus Encyclopedia: Huntington Disease - University of Washington Medical Center: Testing for Huntington Disease: Making an Informed Choice 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
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What is (are) congenital neuronal ceroid lipofuscinosis ?
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Congenital neuronal ceroid lipofuscinosis (NCL) is an inherited disorder that primarily affects the nervous system. Soon after birth, affected infants develop muscle rigidity, respiratory failure, and prolonged episodes of seizure activity that last several minutes (status epilepticus). It is likely that some affected individuals have seizure activity before birth. Infants with congenital NCL have unusually small heads (microcephaly) with brains that may be less than half the normal size. There is a loss of brain cells in areas that coordinate movement and control thinking and emotions (the cerebellum and the cerebral cortex). Affected individuals also lack a fatty substance called myelin, which protects nerve cells and promotes efficient transmission of nerve impulses. Infants with congenital NCL often die hours to weeks after birth. Congenital NCL is the most severe form of a group of NCLs (collectively called Batten disease) that affect the nervous system and typically cause progressive problems with vision, movement, and thinking ability. The different types of NCLs are distinguished by the age at which signs and symptoms first appear.
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How many people are affected by congenital neuronal ceroid lipofuscinosis ?
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Congenital NCL is the rarest type of NCL; approximately 10 cases have been described.
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What are the genetic changes related to congenital neuronal ceroid lipofuscinosis ?
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Mutations in the CTSD gene cause congenital NCL. The CTSD gene provides instructions for making an enzyme called cathepsin D. Cathepsin D is one of a family of cathepsin proteins that act as proteases, which modify proteins by cutting them apart. Cathepsin D is found in many types of cells and is active in lysosomes, which are compartments within cells that digest and recycle different types of molecules. By cutting proteins apart, cathepsin D can break proteins down, turn on (activate) proteins, and regulate self-destruction of the cell (apoptosis). CTSD gene mutations that cause congenital NCL lead to a complete lack of cathepsin D enzyme activity. As a result, proteins and other materials are not broken down properly. In the lysosomes, these materials accumulate into fatty substances called lipopigments. These accumulations occur in cells throughout the body, but neurons are likely particularly vulnerable to damage caused by the abnormal cell materials and the loss of cathepsin D function. Early and widespread cell death in congenital NCL leads to severe signs and symptoms and death in infancy.
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Is congenital neuronal ceroid lipofuscinosis inherited ?
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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.
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What are the treatments for congenital neuronal ceroid lipofuscinosis ?
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These resources address the diagnosis or management of congenital neuronal ceroid lipofuscinosis: - Genetic Testing Registry: Neuronal ceroid lipofuscinosis, congenital 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
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What is (are) ankylosing spondylitis ?
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Ankylosing spondylitis is a form of ongoing joint inflammation (chronic inflammatory arthritis) that primarily affects the spine. This condition is characterized by back pain and stiffness that typically appear in adolescence or early adulthood. Over time, back movement gradually becomes limited as the bones of the spine (vertebrae) fuse together. This progressive bony fusion is called ankylosis. The earliest symptoms of ankylosing spondylitis result from inflammation of the joints between the pelvic bones (the ilia) and the base of the spine (the sacrum). These joints are called sacroiliac joints, and inflammation of these joints is known as sacroiliitis. The inflammation gradually spreads to the joints between the vertebrae, causing a condition called spondylitis. Ankylosing spondylitis can involve other joints as well, including the shoulders, hips, and, less often, the knees. As the disease progresses, it can affect the joints between the spine and ribs, restricting movement of the chest and making it difficult to breathe deeply. People with advanced disease are also more prone to fractures of the vertebrae. Ankylosing spondylitis affects the eyes in up to 40 percent of cases, leading to episodes of eye inflammation called acute iritis. Acute iritis causes eye pain and increased sensitivity to light (photophobia). Rarely, ankylosing spondylitis can also cause serious complications involving the heart, lungs, and nervous system.
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How many people are affected by ankylosing spondylitis ?
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Ankylosing spondylitis is part of a group of related diseases known as spondyloarthropathies. In the United States, spondyloarthropathies affect 3.5 to 13 per 1,000 people.
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What are the genetic changes related to ankylosing spondylitis ?
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Ankylosing spondylitis is likely caused by a combination of genetic and environmental factors, most of which have not been identified. However, researchers have found variations in several genes that influence the risk of developing this disorder. The HLA-B gene provides instructions for making a protein that plays an important role in the immune system. The HLA-B gene is part of 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 HLA-B gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign proteins. A variation of the HLA-B gene called HLA-B27 increases the risk of developing ankylosing spondylitis. Although many people with ankylosing spondylitis have the HLA-B27 variation, most people with this version of the HLA-B gene never develop the disorder. It is not known how HLA-B27 increases the risk of developing ankylosing spondylitis. Variations in several additional genes, including ERAP1, IL1A, and IL23R, have also been associated with ankylosing spondylitis. Although these genes play critical roles in the immune system, it is unclear how variations in these genes affect a person's risk of developing ankylosing spondylitis. Changes in genes that have not yet been identified are also believed to affect the chances of developing ankylosing spondylitis and influence the progression of the disorder. Some of these genes likely play a role in the immune system, while others may have different functions. Researchers are working to identify these genes and clarify their role in ankylosing spondylitis.
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Is ankylosing spondylitis inherited ?
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Although ankylosing spondylitis can occur in more than one person in a family, it is not a purely genetic disease. Multiple genetic and environmental factors likely play a part in determining the risk of developing this disorder. As a result, inheriting a genetic variation linked with ankylosing spondylitis does not mean that a person will develop the condition, even in families in which more than one family member has the disorder. For example, about 80 percent of children who inherit HLA-B27 from a parent with ankylosing spondylitis do not develop the disorder.
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What are the treatments for ankylosing spondylitis ?
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These resources address the diagnosis or management of ankylosing spondylitis: - Genetic Testing Registry: Ankylosing spondylitis - MedlinePlus Encyclopedia: Ankylosing Spondylitis - MedlinePlus Encyclopedia: HLA-B27 Antigen 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
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What is (are) carbamoyl phosphate synthetase I deficiency ?
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Carbamoyl phosphate synthetase I deficiency is an inherited disorder that causes ammonia to accumulate in the blood (hyperammonemia). Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The brain is especially sensitive to the effects of excess ammonia. In the first few days of life, infants with carbamoyl phosphate synthetase I deficiency typically exhibit the effects of hyperammonemia, which may include unusual sleepiness, poorly regulated breathing rate or body temperature, unwillingness to feed, vomiting after feeding, unusual body movements, seizures, or coma. Affected individuals who survive the newborn period may experience recurrence of these symptoms if diet is not carefully managed or if they experience infections or other stressors. They may also have delayed development and intellectual disability. In some people with carbamoyl phosphate synthetase I deficiency, signs and symptoms may be less severe and appear later in life.
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How many people are affected by carbamoyl phosphate synthetase I deficiency ?
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Carbamoyl phosphate synthetase I deficiency is a rare disorder; its overall incidence is unknown. Researchers in Japan have estimated that it occurs in 1 in 800,000 newborns in that country.
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What are the genetic changes related to carbamoyl phosphate synthetase I deficiency ?
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Mutations in the CPS1 gene cause carbamoyl phosphate synthetase I deficiency. The CPS1 gene provides instructions for making the enzyme carbamoyl phosphate synthetase I. This enzyme participates in the urea cycle, which is a sequence of biochemical reactions that occurs in liver cells. The urea cycle processes excess nitrogen, generated when protein is broken down by the body, to make a compound called urea that is excreted by the kidneys. The specific role of the carbamoyl phosphate synthetase I enzyme is to control the first step of the urea cycle, a reaction in which excess nitrogen compounds are incorporated into the cycle to be processed. Carbamoyl phosphate synthetase I deficiency belongs to a class of genetic diseases called urea cycle disorders. In this condition, the carbamoyl phosphate synthetase I enzyme is at low levels (deficient) or absent, and the urea cycle cannot proceed normally. As a result, nitrogen accumulates in the bloodstream in the form of toxic ammonia instead of being converted to less toxic urea and excreted. Ammonia is especially damaging to the brain, and excess ammonia causes neurological problems and other signs and symptoms of carbamoyl phosphate synthetase I deficiency.
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Is carbamoyl phosphate synthetase I deficiency inherited ?
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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.
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What are the treatments for carbamoyl phosphate synthetase I deficiency ?
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These resources address the diagnosis or management of carbamoyl phosphate synthetase I deficiency: - Baby's First Test - Gene Review: Gene Review: Urea Cycle Disorders Overview - Genetic Testing Registry: Congenital hyperammonemia, type I - MedlinePlus Encyclopedia: Hereditary Urea Cycle Abnormality 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
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What is (are) mucopolysaccharidosis type II ?
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Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a condition that affects many different parts of the body and occurs almost exclusively in males. It is a progressively debilitating disorder; however, the rate of progression varies among affected individuals. At birth, individuals with MPS II do not display any features of the condition. Between ages 2 and 4, they develop full lips, large rounded cheeks, a broad nose, and an enlarged tongue (macroglossia). The vocal cords also enlarge, which results in a deep, hoarse voice. Narrowing of the airway causes frequent upper respiratory infections and short pauses in breathing during sleep (sleep apnea). As the disorder progresses, individuals need medical assistance to keep their airway open. Many other organs and tissues are affected in MPS II. Individuals with this disorder often have a large head (macrocephaly), a buildup of fluid in the brain (hydrocephalus), an enlarged liver and spleen (hepatosplenomegaly), and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia). People with MPS II usually have thick skin that is not very stretchy. Some affected individuals also have distinctive white skin growths that look like pebbles. Most people with this disorder develop hearing loss and have recurrent ear infections. Some individuals with MPS II develop problems with the light-sensitive tissue in the back of the eye (retina) and have reduced vision. Carpal tunnel syndrome commonly occurs in children with this disorder and is characterized by numbness, tingling, and weakness in the hand and fingers. Narrowing of the spinal canal (spinal stenosis) in the neck can compress and damage the spinal cord. The heart is also significantly affected by MPS II, and many individuals develop heart valve problems. Heart valve abnormalities can cause the heart to become enlarged (ventricular hypertrophy) and can eventually lead to heart failure. Children with MPS II grow steadily until about age 5, and then their growth slows and they develop short stature. Individuals with this condition have joint deformities (contractures) that significantly affect mobility. Most people with MPS II also have dysostosis multiplex, which refers to multiple skeletal abnormalities seen on x-ray. Dysostosis multiplex includes a generalized thickening of most long bones, particularly the ribs. There are two types of MPS II, called the severe and mild types. While both types affect many different organs and tissues as described above, people with severe MPS II also experience a decline in intellectual function and a more rapid disease progression. Individuals with the severe form begin to lose basic functional skills (developmentally regress) between the ages of 6 and 8. The life expectancy of these individuals is 10 to 20 years. Individuals with mild MPS II also have a shortened lifespan, but they typically live into adulthood and their intelligence is not affected. Heart disease and airway obstruction are major causes of death in people with both types of MPS II.
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How many people are affected by mucopolysaccharidosis type II ?
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MPS II occurs in approximately 1 in 100,000 to 1 in 170,000 males.
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What are the genetic changes related to mucopolysaccharidosis type II ?
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Mutations in the IDS gene cause MPS II. The IDS gene provides instructions for producing the I2S enzyme, which is involved in the breakdown of large sugar molecules called glycosaminoglycans (GAGs). GAGs were originally called mucopolysaccharides, which is where this condition gets its name. Mutations in the IDS gene reduce or completely eliminate the function of the I2S enzyme. Lack of I2S enzyme activity leads to the accumulation of GAGs within cells, specifically inside the lysosomes. Lysosomes are compartments in the cell that digest and recycle different types of molecules. Conditions that cause molecules to build up inside the lysosomes, including MPS II, are called lysosomal storage disorders. The accumulation of GAGs increases the size of the lysosomes, which is why many tissues and organs are enlarged in this disorder. Researchers believe that the GAGs may also interfere with the functions of other proteins inside the lysosomes and disrupt the movement of molecules inside the cell.
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Is mucopolysaccharidosis type II inherited ?
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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.
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What are the treatments for mucopolysaccharidosis type II ?
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These resources address the diagnosis or management of mucopolysaccharidosis type II: - Baby's First Test - Gene Review: Gene Review: Mucopolysaccharidosis Type II - Genetic Testing Registry: Mucopolysaccharidosis, MPS-II - MedlinePlus Encyclopedia: Hunter syndrome - MedlinePlus Encyclopedia: Mucopolysaccharides 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
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What is (are) nonsyndromic holoprosencephaly ?
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Nonsyndromic holoprosencephaly is an abnormality of brain development that also affects the head and face. Normally, the brain divides into two halves (hemispheres) during early development. Holoprosencephaly occurs when the brain fails to divide properly into the right and left hemispheres. This condition is called nonsyndromic to distinguish it from other types of holoprosencephaly caused by genetic syndromes, chromosome abnormalities, or substances that cause birth defects (teratogens). The severity of nonsyndromic holoprosencephaly varies widely among affected individuals, even within the same family. Nonsyndromic holoprosencephaly can be grouped into four types according to the degree of brain division. From most to least severe, the types are known as alobar, semi-lobar, lobar, and middle interhemispheric variant (MIHV). In the most severe forms of nonsyndromic holoprosencephaly, the brain does not divide at all. These affected individuals have one central eye (cyclopia) and a tubular nasal structure (proboscis) located above the eye. Most babies with severe nonsyndromic holoprosencephaly die before birth or soon after. In the less severe forms, the brain is partially divided and the eyes are usually set close together (hypotelorism). The life expectancy of these affected individuals varies depending on the severity of symptoms. People with nonsyndromic holoprosencephaly often have a small head (microcephaly), although they can develop a buildup of fluid in the brain (hydrocephalus) that causes increased head size (macrocephaly). Other features may include an opening in the roof of the mouth (cleft palate) with or without a split in the upper lip (cleft lip), one central front tooth instead of two (a single maxillary central incisor), and a flat nasal bridge. The eyeballs may be abnormally small (microphthalmia) or absent (anophthalmia). Some individuals with nonsyndromic holoprosencephaly have a distinctive pattern of facial features, including a narrowing of the head at the temples, outside corners of the eyes that point upward (upslanting palpebral fissures), large ears, a short nose with upturned nostrils, and a broad and deep space between the nose and mouth (philtrum). In general, the severity of facial features is directly related to the severity of the brain abnormalities. However, individuals with mildly affected facial features can have severe brain abnormalities. Some people do not have apparent structural brain abnormalities but have some of the facial features associated with this condition. These individuals are considered to have a form of the disorder known as microform holoprosencephaly and are typically identified after the birth of a severely affected family member. Most people with nonsyndromic holoprosencephaly have developmental delay and intellectual disability. Affected individuals also frequently have a malfunctioning pituitary gland, which is a gland located at the base of the brain that produces several hormones. Because pituitary dysfunction leads to the partial or complete absence of these hormones, it can cause a variety of disorders. Most commonly, people with nonsyndromic holoprosencephaly and pituitary dysfunction develop diabetes insipidus, a condition that disrupts the balance between fluid intake and urine excretion. Dysfunction in other parts of the brain can cause seizures, feeding difficulties, and problems regulating body temperature, heart rate, and breathing. The sense of smell may be diminished (hyposmia) or completely absent (anosmia) if the part of the brain that processes smells is underdeveloped or missing.
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How many people are affected by nonsyndromic holoprosencephaly ?
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Nonsyndromic holoprosencephaly accounts for approximately 25 to 50 percent of all cases of holoprosencephaly, which affects an estimated 1 in 10,000 newborns.
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What are the genetic changes related to nonsyndromic holoprosencephaly ?
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Mutations in 11 genes have been found to cause nonsyndromic holoprosencephaly. These genes provide instructions for making proteins that are important for normal embryonic development, particularly for determining the shape of the brain and face. About 25 percent of people with nonsyndromic holoprosencephaly have a mutation in one of these four genes: SHH, ZIC2, SIX3, or TGIF1. Mutations in the other genes related to nonsyndromic holoprosencephaly are found in only a small percentage of cases. Many individuals with this condition do not have an identified gene mutation. The cause of the disorder is unknown in these individuals. The brain normally divides into right and left hemispheres during the third to fourth week of pregnancy. To establish the line that separates the two hemispheres (the midline), the activity of many genes must be tightly regulated and coordinated. These genes provide instructions for making signaling proteins, which instruct the cells within the brain to form the right and left hemispheres. Signaling proteins are also important for the formation of the eyes. During early development, the cells that develop into the eyes form a single structure called the eye field. This structure is located in the center of the developing face. The signaling protein produced from the SHH gene causes the eye field to separate into two distinct eyes. The SIX3 gene is involved in the formation of the lens of the eye and the specialized tissue at the back of the eye that detects light and color (the retina). Mutations in the genes that cause nonsyndromic holoprosencephaly lead to the production of abnormal or nonfunctional signaling proteins. Without the correct signals, the eyes will not form normally and the brain does not separate into two hemispheres. The development of other parts of the face is affected if the eyes do not move to their proper position. The signs and symptoms of nonsyndromic holoprosencephaly are caused by abnormal development of the brain and face. Researchers believe that other genetic or environmental factors, many of which have not been identified, play a role in determining the severity of nonsyndromic holoprosencephaly.
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Is nonsyndromic holoprosencephaly inherited ?
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Nonsyndromic holoprosencephaly is inherited in an autosomal dominant pattern, which means an alteration in one copy of a gene in each cell is usually sufficient to cause the disorder. However, not all people with a gene mutation will develop signs and symptoms of the condition. In some cases, an affected person inherits the mutation from one parent who may or may not have mild features of the condition. Other cases result from a new gene mutation and occur in people with no history of the disorder in their family.
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What are the treatments for nonsyndromic holoprosencephaly ?
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These resources address the diagnosis or management of nonsyndromic holoprosencephaly: - Gene Review: Gene Review: Holoprosencephaly Overview - Genetic Testing Registry: Holoprosencephaly 1 - Genetic Testing Registry: Holoprosencephaly 10 - Genetic Testing Registry: Holoprosencephaly 2 - Genetic Testing Registry: Holoprosencephaly 3 - Genetic Testing Registry: Holoprosencephaly 4 - Genetic Testing Registry: Holoprosencephaly 5 - Genetic Testing Registry: Holoprosencephaly 6 - Genetic Testing Registry: Holoprosencephaly 7 - Genetic Testing Registry: Holoprosencephaly 8 - Genetic Testing Registry: Holoprosencephaly 9 - Genetic Testing Registry: Holoprosencephaly sequence - Genetic Testing Registry: NODAL-Related Holoprosencephaly 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
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What is (are) juvenile Paget disease ?
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Juvenile Paget disease is a disorder that affects bone growth. This disease causes bones to be abnormally large, misshapen, and easily broken (fractured). The signs of juvenile Paget disease appear in infancy or early childhood. As bones grow, they become progressively weaker and more deformed. These abnormalities usually become more severe during the adolescent growth spurt, when bones grow very quickly. Juvenile Paget disease affects the entire skeleton, resulting in widespread bone and joint pain. The bones of the skull tend to grow unusually large and thick, which can lead to hearing loss. The disease also affects bones of the spine (vertebrae). The deformed vertebrae can collapse, leading to abnormal curvature of the spine. Additionally, weight-bearing long bones in the legs tend to bow and fracture easily, which can interfere with standing and walking.
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How many people are affected by juvenile Paget disease ?
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Juvenile Paget disease is rare; about 50 affected individuals have been identified worldwide.
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What are the genetic changes related to juvenile Paget disease ?
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Juvenile Paget disease is caused by mutations in the TNFRSF11B gene. This gene provides instructions for making a protein that is involved in bone remodeling, a normal process in which old bone is broken down 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 the TNFRSF11B gene lead to a much faster rate of bone remodeling starting early in life. Bone tissue is broken down more quickly than usual, and when new bone tissue grows it is larger, weaker, and less organized than normal bone. This abnormally fast bone remodeling underlies the problems with bone growth characteristic of juvenile Paget disease.
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Is juvenile Paget disease inherited ?
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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.
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What are the treatments for juvenile Paget disease ?
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These resources address the diagnosis or management of juvenile Paget disease: - Genetic Testing Registry: Hyperphosphatasemia with bone 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
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What is (are) hyperkalemic periodic paralysis ?
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Hyperkalemic periodic paralysis is a condition that causes episodes of extreme muscle weakness or paralysis, usually beginning in infancy or early childhood. Most often, these episodes involve a temporary inability to move muscles in the arms and legs. Episodes tend to increase in frequency until mid-adulthood, after which they occur less frequently. Factors that can trigger attacks include rest after exercise, potassium-rich foods such as bananas and potatoes, stress, fatigue, alcohol, pregnancy, exposure to cold temperatures, certain medications, and periods without food (fasting). Muscle strength usually returns to normal between attacks, although many affected people continue to experience mild stiffness (myotonia), particularly in muscles of the face and hands. Most people with hyperkalemic periodic paralysis have increased levels of potassium in their blood (hyperkalemia) during attacks. Hyperkalemia results when the weak or paralyzed muscles release potassium ions into the bloodstream. In other cases, attacks are associated with normal blood potassium levels (normokalemia). Ingesting potassium can trigger attacks in affected individuals, even if blood potassium levels do not go up.
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How many people are affected by hyperkalemic periodic paralysis ?
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Hyperkalemic periodic paralysis affects an estimated 1 in 200,000 people.
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What are the genetic changes related to hyperkalemic periodic paralysis ?
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Mutations in the SCN4A gene can cause hyperkalemic periodic paralysis. The SCN4A gene provides instructions for making a protein that plays an essential role in muscles used for movement (skeletal muscles). For the body to move normally, these muscles must tense (contract) and relax in a coordinated way. One of the changes that helps trigger muscle contractions is the flow of positively charged atoms (ions), including sodium, into 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 stay open too long or do not stay closed long enough, allowing more sodium ions to flow into muscle cells. This increase in sodium ions triggers the release of potassium from muscle cells, which causes more sodium channels to open and stimulates the flow of even more sodium ions into these cells. These changes in ion transport reduce the ability of skeletal muscles to contract, leading to episodes of muscle weakness or paralysis. In 30 to 40 percent of cases, the cause of hyperkalemic periodic paralysis is unknown. Changes in other genes, which have not been identified, likely cause the disorder in these cases.
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Is hyperkalemic periodic paralysis inherited ?
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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.
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What are the treatments for hyperkalemic periodic paralysis ?
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These resources address the diagnosis or management of hyperkalemic periodic paralysis: - Gene Review: Gene Review: Hyperkalemic Periodic Paralysis - Genetic Testing Registry: Familial hyperkalemic periodic paralysis - Genetic Testing Registry: Hyperkalemic Periodic Paralysis Type 1 - MedlinePlus Encyclopedia: Hyperkalemic Periodic Paralysis - 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
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What is (are) myotonia congenita ?
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Myotonia congenita is a disorder that affects muscles used for movement (skeletal muscles). Beginning in childhood, people with this condition experience bouts of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally. Although myotonia can affect any skeletal muscles, including muscles of the face and tongue, it occurs most often in the legs. Myotonia causes muscle stiffness that can interfere with movement. In some people the stiffness is very mild, while in other cases it may be severe enough to interfere with walking, running, and other activities of daily life. These muscle problems are particularly noticeable during movement following a period of rest. Many affected individuals find that repeated movements can temporarily alleviate their muscle stiffness, a phenomenon known as the warm-up effect. The two major types of myotonia congenita are known as Thomsen disease and Becker disease. These conditions are distinguished by the severity of their symptoms and their patterns of inheritance. Becker disease usually appears later in childhood than Thomsen disease and causes more severe muscle stiffness, particularly in males. People with Becker disease often experience temporary attacks of muscle weakness, particularly in the arms and hands, brought on by movement after periods of rest. They may also develop mild, permanent muscle weakness over time. This muscle weakness is not seen in people with Thomsen disease.
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How many people are affected by myotonia congenita ?
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Myotonia congenita is estimated to affect 1 in 100,000 people worldwide. This condition is more common in northern Scandinavia, where it occurs in approximately 1 in 10,000 people.
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What are the genetic changes related to myotonia congenita ?
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Mutations in the CLCN1 gene cause myotonia congenita. The CLCN1 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 contraction and relaxation are controlled by the flow of charged atoms (ions) into and out of muscle cells. Specifically, the protein produced from the CLCN1 gene forms a channel that controls the flow of negatively charged chlorine atoms (chloride ions) into these cells. The main function of this channel is to stabilize the cells' electrical charge, which prevents muscles from contracting abnormally. Mutations in the CLCN1 gene alter the usual structure or function of chloride channels. The altered channels cannot properly regulate ion flow, reducing the movement of chloride ions into skeletal muscle cells. This disruption in chloride ion flow triggers prolonged muscle contractions, which are the hallmark of myotonia.
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Is myotonia congenita inherited ?
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The two forms of myotonia congenita have different patterns of inheritance. Thomsen disease 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 most cases, an affected person has one parent with the condition. Becker disease is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition. Because several CLCN1 mutations can cause either Becker disease or Thomsen disease, doctors usually rely on characteristic signs and symptoms to distinguish the two forms of myotonia congenita.
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What are the treatments for myotonia congenita ?
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These resources address the diagnosis or management of myotonia congenita: - Gene Review: Gene Review: Myotonia Congenita - Genetic Testing Registry: Congenital myotonia, autosomal dominant form - Genetic Testing Registry: Congenital myotonia, autosomal recessive form - Genetic Testing Registry: Myotonia congenita - MedlinePlus Encyclopedia: Myotonia congenita 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
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What is (are) Cohen syndrome ?
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Cohen syndrome is an inherited disorder that affects many parts of the body and is characterized by developmental delay, intellectual disability, small head size (microcephaly), and weak muscle tone (hypotonia). Other features include progressive nearsightedness (myopia), degeneration of the light-sensitive tissue at the back of the eye (retinal dystrophy), an unusually large range of joint movement (hypermobility), and distinctive facial features. Characteristic facial features include thick hair and eyebrows, long eyelashes, unusually-shaped eyes (down-slanting and wave-shaped), a bulbous nasal tip, a smooth or shortened area between the nose and the upper lip (philtrum), and prominent upper central teeth. The combination of the last two facial features results in an open-mouth appearance. The features of Cohen syndrome vary widely among affected individuals. Additional signs and symptoms in some individuals with this disorder include low levels of white blood cells (neutropenia), overly friendly behavior, and obesity that develops in late childhood or adolescence. When obesity is present, it typically develops around the torso, with the arms and legs remaining slender. Individuals with Cohen syndrome may also have narrow hands and feet, and slender fingers.
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How many people are affected by Cohen syndrome ?
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The exact incidence of Cohen syndrome is unknown. It has been diagnosed in fewer than 1,000 people worldwide. More cases are likely undiagnosed.
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