Gaucher disease type 1 (GD1) is the most common form of Gaucher disease. Like other types of Gaucher disease, GD1 is caused when not enough glucocerebrosidase (GBA) is made. GBA is an important enzyme that breaks down a fatty chemical called glucocerebroside.[1][2][3] Because the body cannot break down this chemical, fat-filled Gaucher cells build up in…

47, XYY syndrome is a syndrome (group of signs and symptoms) that affects males. For some males with this syndrome, signs and symptoms are barely noticeable. For others, signs and symptoms may include learning disabilities, speech delay, low muscle tone (hypotonia), and being taller than expected.[1][2] 47, XYY syndrome is caused by having an extra…

Spinal muscular atrophy type 2 (SMA2) is a genetic neuromuscular disorder that affects the nerve cells that control voluntary muscles (motor neurons). Without treatment, progressive muscle weakness develops in babies with SMA2 between ages 6 and 12 months. Babies with SMA2 can sit without support, however, they cannot stand or walk independently. Feeding and breathing problems…

Hyperkalemic periodic paralysis is a genetic disease that causes episodes of extreme muscle weakness and an increase of the potassium levels in the blood. Muscle weakness during an attack usually affects the arms and legs and muscles of the eyes, throat, and trunk. Most often, these episodes involve a temporary inability to move muscles in…

Oculocutaneous albinism is a group of conditions that affect the coloring of the hair and eyes. Individuals affected by oculocutaneous albinism have very light skin and light-colored irises; they may also have vision problems such as decreased sharpness of vision, rapid eye movements (nystagmus), crossed eyes (strabismus), or increased sensitivity to light (photophobia). All types…

Fabry disease is a type of lysosomal storage disease. Lysosomes are round structures found in the cells of the body that are full of special proteins called enzymes. Lysosomal enzymes help breakdown other proteins, carbohydrates, fats, and other substances. In Fabry disease, there is not enough of the enzyme alpha-galactosidase (alpha-GAL). Alpha-GAL helps breakdown a…

Takayasu arteritis is a condition that causes inflammation of the main blood vessel that carries blood from the heart to the rest of the body (aorta) and its associated branched blood vessels. As a result of the inflammation, the blood vessel walls become thick and make it difficult for blood to flow. Over time, impaired blood flow…

Fragile X syndrome is a genetic condition involving changes in part of the X chromosome.[1] This condition causes a range of developmental problems including learning disabilities and cognitive impairment.[2] It is the most common form of inherited intellectual disability in males and a significant cause of intellectual disability in females.[1] Other signs and symptoms may include…

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Pendred syndrome is a condition usually characterized by sensorineural hearing loss in both ears (bilateral) and euthyroid goiter (enlargement of the thyroid gland with normal thyroid gland function). The amount of hearing loss varies among affected people. In many cases, significant hearing loss is present at birth. In other cases, hearing loss does not develop…

Heterotaxy is a condition characterized by internal organs that are not arranged as would be expected in the chest and abdomen. Organs are expected to be in a particular orientation inside of the body, known as situs solitus. Heterotaxy occurs when the organs are not in this typical orientation, but are instead in different positions…

Beckwith-Wiedemann syndrome (BWS) is a growth disorder that can affect several parts of the body. Babies and children are larger than normal usually until age 8, when growth slows down, resulting in an average height in adults. Symptoms may include one side or area of the body growing more than the other side (asymmetric growth…

Cornelia de Lange syndrome (CdLS) is a developmental disorder that affects many parts of the body. The severity of the condition and the associated signs and symptoms can vary widely, but may include distinctive facial characteristics, growth delays, intellectual disability and limb defects. Approximately 60% of people affected by CdLS have a disease-causing variation (mutation)…

Leber hereditary optic neuropathy (LHON) is a condition characterized by vision loss. Vision loss is typically the only symptom of LHON. Some families with additional signs and symptoms have been reported and are said to have “LHON plus“, a condition which includes vision loss, tremors, and abnormalities of the electrical signals that control the heartbeat…

Congenital bilateral absence of the vas deferens (CBAVD) occurs in males when the tubes that carry sperm out of the testes (vas deferens) fail to develop properly. Although the testes usually develop and function normally, sperm cannot be transported through the vas deferens to become part of semen. As a result, men with this condition are…

Meconium aspiration syndrome is a serious condition in which a newborn breathes a mixture of meconium and amniotic fluid into the lungs around the time of delivery. This can cause breathing difficulties due to swelling (inflammation) in the baby’s lungs after birth. Treatment may include suctioning the newborn’s mouth as soon as the head emerges…

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs. Orpha Number: 1941 Definition Juvenile absence epilepsy (JAE) is a genetic epilepsy with onset occurring around puberty. JAE is characterized by sporadic occurrence of absence seizures, frequently associated with a long-life prevalence of generalized tonic-clonic seizures (GTCS)…

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs. Orpha Number: 54370 Definition Membranoproliferative glomerulonephritis (MPGN) is a chronic progressive kidney disorder characterized by glomerular capillary wall structural changes and mesangial cell proliferation leading to nephrotic syndrome, hypocomplementemia, hypertension, proteinuria and end-stage kidney disease. MPGN can…

Chromosome 18p deletion is a chromosome abnormality that occurs when there is a missing (deleted) copy of genetic material on the short arm (p) of chromosome 18. The severity of the condition and the signs and symptoms depend on the size and location of the deletion and which genes are involved. Features that often occur…

Mucopolysaccharidosis type III (MPS III) is a genetic disorder that makes the body unable to break down large sugar molecules called glycosaminoglycans (GAGs, formerly called mucopolysaccharides).[1][2] Specifically, people with this condition are unable to break down a GAG called heparan sulfate.[2] Affected individuals can have severe neurological symptoms, including progressive dementia, aggressive behavior, hyperactivity, seizures, deafness, loss…

Syndactyly type 1 is a congenital limb developmental defect that involves webbing or joining of the fingers or toes. Syndactyly type 1 is the most common type of non-syndromic syndactyly. Individuals with syndactyly type 1 have webbing of the third and fourth fingers and/or between the second and third toes. Other digits may be involved, as…

Cleidocranial dysplasia (CCD) affects the development of the bones, skull, and teeth. Signs and symptoms include underdeveloped or absent collarbones (clavicles), dental abnormalities, and delayed closing of the spaces between the skull bones (fontanels). Other symptoms may include decreased bone density (osteopenia), hearing loss, bone abnormalities of the hands, and recurrent sinus and ear infections. People with…

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs. Orpha Number: 100984 Definition A rare, pure or complex subtype of hereditary spastic paraplegia, with highly variable phenotype, typically characterized by childhood-onset of minimally progressive, bilateral, mainly symmetric lower limb spasticity and weakness, associated with pes cavus,…

Osteosarcoma is the most common type of bone cancer. The average age at diagnosis is 15. Boys and girls have a similar incidence of this tumor until late adolescence, at which time boys are more commonly affected. In rare cases, osteosarcoma occurs in adults. Although osteosarcoma tends to occur in the larger bones, such as the…

Walker-Warburg syndrome (WWS) is a severe form of congenital muscular dystrophy associated with brain and eye abnormalities. Signs and symptoms are typically present at birth and include hypotonia, muscle weakness, developmental delay, intellectual disability and occasional seizures. It is also associated with lissencephaly, hydrocephalus, cerebellar malformations, eye abnormalities, and other abnormalities. Most children do not…

Tularemia is an infection caused by the bacterium Francisella tularensis. It is more common in rodents and rabbits but has been found in other animals including domestic cats, sheep, birds, and hamsters. Humans can become infected in several different ways: by handling infected animals, through tick or deer fly bites, by drinking contaminated water, or…

Autosomal dominant hyper IgE syndrome (AD-HIES), formerly known as Job syndrome, affects several body systems including the immune system. AD-HIES is characterized by abnormally high levels of an immune system protein called immunoglobulin E (IgE) in the blood. Signs and symptoms may include recurrent infections (e.g., pneumonia, skin infections), eczema, and occasionally bone and tooth abnormalities. The eczema and skin infections may cause rashes,…

Ollier disease is a skeletal disorder characterized by multiple enchondromas, which are noncancerous (benign) growths of cartilage that develop within the bones. These growths may lead to skeletal deformities, limb discrepancy, and fractures.[1][2][3][4] The enchondromas primarily occur in the limb bones, especially the bones of the hands and feet. They tend to develop near the ends…

Autoimmune hepatitis is a disease in which the body’s immune system attacks liver cells. This immune response causes inflammation of the liver, also called hepatitis. The disease can be quite serious and, if not treated, gets worse over time, leading to cirrhosis of the liver and/or liver failure. Autoimmune hepatitis likely results from a combination of autoimmunity, environmental triggers, and…

Krabbe disease affects the development and function of the nervous system. There are several types of Krabbe disease that differ based on the age that symptoms begin. The early-onset type of Krabbe disease is the most common and the most severe. Babies who have early-onset (infantile) Krabbe disease typically develop features in the first six months…

Wilson disease is a rare inherited disorder that is characterized by the accumulation of copper in the body. Because high levels of copper are toxic to tissues and organs, this buildup can lead to damage of the liver, brain and eyes. Signs and symptoms of Wilson disease include chronic liver disease, central nervous system abnormalities, and…

Epidermolytic ichthyosis (EI) is a rare, genetic skin disorder. It becomes apparent at birth, or shortly after birth, with reddening, scaling, and severe blistering of the skin. Hyperkeratosis (thickening of the skin) develops within months and worsens over time. Blister formation decreases, but may still occur after skin trauma or during summer months. Skin can be itchy…

Biotinidase deficiency is an inherited disorder in which the body is unable to recycle the vitamin biotin. The disorder may become apparent in the first few months of life, or later in childhood. The more severe form of the disorder is called ‘profound biotinidase deficiency’ and may cause delayed development, seizures, weak muscle tone (hypotonia),…

Charcot-Marie-Tooth disease type 1A (CMT1A) is a type of inherited neurological disorder that affects the peripheral nerves. People with this disease experience weakness and wasting (atrophy) of the muscles of the lower legs beginning in adolescence; later they can also have hand weakness and sensory loss.[1] In CMT1A, abnormal nerve conduction studies can be found in babies or…

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Congenital cytomegalovirus (congenital CMV) is a group of symptoms that may occur when an infant is infected with the cytomegalovirus before birth. Most infants who are infected with the virus never develop symptoms of the condition. However, approximately 10% of babies will experience health problems and/or disabilities such as problems with the lungs, liver and/or…

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Hairy cell leukemia is a rare, slow-growing cancer of the blood in which the bone marrow makes too many B cells (lymphocytes), a type of white blood cell that fights infection. The condition is named after these excess B cells which look ‘hairy’ under a microscope. As the number of leukemia cells increases, fewer healthy white…

Currarino triad or syndrome is an autosomal dominant hereditary condition which is characterized by the triad of sacral agenesis abnormalities (abnormally developed lower spine), anorectal malformation (most commonly in the form of anorectal stenosis) and presacral mass consisting of a teratoma, anterior sacral meningocele or both. However only 1 out of 5 cases of Currarino…

Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare autoimmune lung disorder. It is the most common form (90% of the cases) of pulmonary alveolar proteinosis (PAP). Most cases affect adults between the ages of 20-50 years. Some people may not show symptoms, while others may have progressive difficulty breathing and shortness of breath upon exertion. Other signs and symptoms may include…

Guillain-Barré syndrome (GBS) is a rare syndrome in which the body’s immune system attacks part of the peripheral nervous system. The peripheral nervous system carries signals from the brain to the muscles. Symptoms of GBS include muscle weakness, numbness, and tingling sensations, which can increase in intensity until the muscles cannot be used at all (paralysis).[1]…

Limb-girdle muscular dystrophy type 2C (LGMD2C) is a genetic condition that affects the voluntary muscles around the hips and shoulders. This condition belongs to a group of muscle disorders called limb-girdle muscular dystrophies, which are characterized by progressive loss of muscle bulk and symmetrical weakening of voluntary muscles. Symptoms of LGMD2C usually appear around 6-8 years of age,…

Anaplastic large cell lymphoma (ALCL) is a rare type of Non-Hodgkins lymphoma. Lymphoma is a cancer of the lymph system, part of our immune system. Non-Hodgkins lymphoma involves abnormal growth of white blood cells, either T cells or B cells. Anaplastic large cell lymphoma is an aggressive cancer that usually involves the T-cells. Cancer cells…

Hereditary spastic paraplegia (HSP) is a group of hereditary, degenerative, neurological disorders that primarily affect the upper motor neurons. Upper motor neurons in the brain and spinal cord deliver signals to the lower motor neurons, which in turn, carry messages to the muscles. In hereditary spastic paraplegia, upper motor neurons slowly degenerate so the muscles do not receive…

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart condition in which the muscle of the right ventricle of the heart is replaced by fat and/or scar tissue. The condition is progressive and over time the right ventricle loses the ability to pump blood.[1] Individuals with ARVC often develop abnormal heart rhythms known as arrhythmias, which can increase…

Laron syndrome is a condition that occurs when the body is unable to utilize growth hormone. It is primarily characterized by short stature. Other signs and symptoms vary but may include reduced muscle strength and endurance; hypoglycemia in infancy; delayed puberty; short limbs (arms and legs); and obesity. It is often caused by changes (mutations) in…

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a genetic disorder that causes an abnormally fast and irregular heart rhythm in response to physical activity or emotional stress. Signs and symptoms include light-headedness, dizziness, and fainting. Symptoms most often develop between 7 to 9 years of age. If untreated CPVT can cause a heart attack and death. CPVT is caused…

Dentinogenesis imperfecta is a condition characterized by teeth that are translucent and discolored (most often blue-grey or yellow-brown in color). Individuals with this disorder tend to have teeth that are weaker than normal, which leads to wear, breakage, and loss of teeth. This damage can include teeth fractures or small holes (pitting) in the enamel….

Malaria is a serious and sometimes fatal disease caused by a parasite that commonly infects a certain type of mosquito which feeds on humans. Infection with malaria parasites may result in a wide variety of symptoms, ranging from absent or very mild symptoms to severe disease and even death. People who get malaria are typically…

Mixed connective tissue disease (MCTD) is a rare autoimmune disorder that is characterized by features commonly seen in three different connective tissue disorders: systemic lupus erythematosus, scleroderma, and polymyositis. Some affected people may also have symptoms of rheumatoid arthritis.[1] Although MCTD can affect people of all ages, it appears to be most common in women…

Reactive arthritis is a type of infectious arthritis that occurs as a “reaction” to an infection elsewhere in the body. This process may occur weeks or even months after the infection has resolved.[1][2] In addition to joint inflammation, reactive arthritis is associated with two other symptoms: redness and inflammation of the eyes (conjunctivitis) and inflammation of the urinary tract…

Polycythemia vera is a condition characterized by an increased number of red blood cells in the bloodstream (erythrocytosis). Affected people may also have excess white blood cells and platelets. Conditions where the body makes too many of these cells are known as myeloproliferative neoplasms.[1] These extra cells cause the blood to be thicker than normal,…

Miyoshi myopathy is a type of muscular dystrophy characterized by muscle weakness and atrophy (wasting), mainly in the distal parts of the legs.[1] The first symptoms typically begin in young adulthood (on average 20 years of age) and include weakness and atrophy of the calves (sometimes asymmetrically), leading to inability to jump, run or walk on tiptoes. Over…

Spinocerebellar ataxia type 6 (SCA6) is a neurological condition characterized by progressive problems with movement. Initial symptoms include problems with coordination and balance (ataxia). Other early signs and symptoms include speech difficulties (dysarthria), involuntary eye movements (nystagmus), and double vision. Over time, individuals with SCA6 may develop loss of coordination in their arms, tremors, and uncontrolled muscle…

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs. Orpha Number: 1209 Definition Tricuspid atresia is (TA) a rare congenital heart malformation characterized by the congenital agenesis of tricuspid valve leading to severe hypoplasia of right ventricle (functionally univentricular). TA is associated with normally related or…

Vernal keratoconjunctivitis (VKC) is a chronic, severe allergy that affects the surfaces of the eyes. It most commonly occurs in boys living in warm, dry climates. Attacks associated with VKC are common in the spring (hence the name “vernal”) and summer but often reoccur in the winter.[1][2] Signs and symptoms usually begin before 10 years of age and…

Clouston syndrome is a form of ectodermal dysplasia that is characterized by abnormalities of the skin, hair and nails. Early signs and symptoms generally begin in infancy and may include nail abnormalities and sparse scalp hair that is wiry, brittle, patchy and pale. Progressive hair loss may lead to total alopecia by puberty. Affected people may…

Acute intermittent porphyria (AIP) is one of the liver (hepatic) porphyrias. AIP is caused by low levels of porphobilinogen deaminase (PBGD), an enzyme also often called hydroxymethylbilane synthase. The low levels of PBGD are generally not sufficient to cause symptoms; however, activating factors such as hormones, drugs, and dietary changes may trigger symptoms. Although most individuals with AIP…

Primary lateral sclerosis (PLS) is a rare neuromuscular disease that affects the nerve cells that control the voluntary muscles. Problems in the legs (such as weakness, stiffness, spasticity, and balance problems) are often observed first, but hand clumsiness and changes in speech can be early symptoms, as well. The condition is progressive (gradually becomes worse…

Oculocutaneous albinism type 1 is a condition that affects the coloring of the skin, hair, and eyes. Signs and symptoms include very fair skin, white hair, an increased risk for skin damage with sun exposure, reduced vision (sharpness), light colored irises, nystagmus, and photophobia (eyes are sensitive to light). It is caused by changes in the TYR…

Complete androgen insensitivity syndrome is a condition that affects sexual development before birth and during puberty. People with this condition are genetically male (one X and one Y chromosome) but do not respond to male hormones at all. As a result, they generally have normal female external genitalia and female breasts. However, they do not…

Townes-Brocks syndrome is a genetic condition characterized by an obstruction of the anal opening (imperforate anus), abnormally shaped ears, and thumb malformations. Most affected individuals have at least two of these three main features. Other signs and symptoms may include kidney abnormalities, hearing loss, heart defects, genital malformations and intellectual disability. The condition is caused by…

Metachromatic leukodystrophy is an inherited condition characterized by the accumulation of fats called sulfatides in cells, especially cells of the nervous system. This accumulation results in progressive destruction of white matter of the brain, which consists of nerve fibers covered by myelin. Affected individuals experience progressive deterioration of intellectual functions and motor skills, such as the…

Mucopolysaccharidosis II (MPS II) is an inherited disorder of carbohydrate metabolism that occurs almost exclusively in males. It is characterized by distinctive facial features, a large head, hydrocephalus, enlargement of the liver and spleen (hepatosplenomegaly), umbilical or inguinal hernia, and hearing loss. Individuals with this condition may additionally have joint deformities and heart abnormalities involving the valves. MPS II…

Behçet disease is a chronic multisystem inflammatory disorder characterized by ulcers affecting the mouth and genitals, various skin lesions, and abnormalities affecting the eyes. In some people, the disease also results in arthritis (swollen, painful, stiff joints), skin problems, and inflammation of the digestive tract, brain, and spinal cord.[1][2][3] Although it can happen at any age, symptoms generally begin…

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs. Orpha Number: 678 Definition Papillon-Lefèvre syndrome (PLS) is a rare ectodermal dysplasia characterized by palmoplantar keratoderma associated with early-onset periodontitis. Epidemiology The prevalence is estimated between 1/250,000 and 1/1,000,000 individuals. The male to female ratio is 1:1….

Intraocular melanoma is a cancer of the pigment-producing cells (melanocytes) in the middle layer of the eye, called the uveal tract.[1] The uveal tract has 3 main parts: (1) the choroid (the tissue layer filled with blood vessels); (2) the ciliary body (the ring of muscle tissue that changes the size of the pupil and the shape of the…

Familial lipoprotein lipase deficiency is a rare genetic disorder is which a person lacks the enzyme lipoprotein lipase, a protein needed to break down fat molecules. Deficiency of this enzyme prevents affected individuals from properly digesting certain fats. This results in the accumulation of fatty droplets called chylomicrons in the blood and an increase in…

Waardenburg syndrome (WS) is a group of genetic conditions characterized by varying degrees of hearing loss and differences in the coloring (pigmentation) of the eyes, hair, and skin. Signs and symptoms can vary both within and between families. Common features include congenital sensorineural deafness; pale blue eyes, different colored eyes, or two colors within one eye; a…

Friedreich ataxia is an inherited condition that affects the nervous system and causes movement problems. People with this condition develop impaired muscle coordination (ataxia) that worsens over time. Other features include the gradual loss of strength and sensation in the arms and legs, muscle stiffness (spasticity), and impaired speech. Many individuals have a form of heart…

Ectodermal dysplasias (ED) are a group of more than 180 disorders that affect the outer layer of tissue of the embryo (ectoderm) that helps make up the skin, sweat glands, hair, teeth, and nails. Symptoms of ED can range from mild to severe and may include teeth abnormalities; brittle, sparse or absent hair; abnormal fingernails;…

Congenital adrenal hyperplasia (CAH) refers to a group of genetic conditions that affect the adrenal glands. These glands sit on top of the kidneys and are responsible for releasing various types of hormones that the body needs to function. Affected people lack an enzyme the adrenal glands need to make one or more of these…

Spinal muscular atrophy (SMA) is a group of genetic neuromuscular disorders that affect the nerve cells that control voluntary muscles (motor neurons). The loss of motor neurons causes progressive muscle weakness and loss of movement due to muscle wasting (atrophy). The severity of the symptoms, the age at which symptoms, begin, and genetic cause varies…

Rett syndrome is a progressive, neuro-developmental condition that primarily affects girls. Affected girls appear to have normal psychomotor development during the first 6 to 18 months of life, followed by a developmental “plateau,” and then rapid regression in language and motor skills. Additional signs and symptoms may include repetitive, stereotypic hand movements; fits of screaming…

Focal segmental glomerulosclerosis (FSGS) is a type of kidney disorder. It is characterized by scar tissue that forms in some of the glomeruli in the kidney.[1] FSGS may cause non-specific signs and symptoms, including protein in the urine, elevated levels of creatinine, and swelling.[2][3] In many cases the cause of FSGS can not be determined. Some…

Lennox-Gastaut syndrome is a form of severe epilepsy that begins in childhood. It is characterized by multiple types of seizures and intellectual disability.[1] This condition can be caused by brain malformations, perinatal asphyxia (lack of oxygen), severe head injury, central nervous system infection and inherited degenerative or metabolic conditions. In about one-third of cases, no…

Immune thrombocytopenic purpura (ITP) is a bleeding disorder characterized by too few platelets in the blood. This is because platelets are being destroyed by the immune system. Symptoms may include bruising, nosebleed or bleeding in the mouth, bleeding into the skin, and abnormally heavy menstruation. With treatment, the chance of remission (a symptom-free period) is…

Autoimmune hemolytic anemia (AIHA) occurs when your immune system makes antibodies that attack your red blood cells. This causes a drop in the number of red blood cells, leading to hemolytic anemia.[1][2][3][4] Symptoms may include unusual weakness and fatigue with tachycardia and breathing difficulties, jaundice, dark urine and/or splenomegaly. AIHA can be primary (idiopathic) or result from…

IgA nephropathy is a kidney disorder that occurs when IgA (immunoglobulin A), a protein that helps the body fight infections, settles in the kidneys. IgA nephropathy can occur at any age, even in childhood. After many years, deposits of IgA may cause the kidneys to leak blood and sometimes protein in the urine. In the early…

Narcolepsy is a chronic brain disorder that involves poor control of sleep-wake cycles. People with narcolepsy have episodes of extreme daytime sleepiness and sudden, irresistible bouts of sleep (called “sleep attacks”) that can occur at any time, and may last from seconds or minutes. Other signs and symptoms may include cataplexy (a sudden loss of…