177 Most Rarest Diseases in the World

Factor XIII deficiency occurs exceedingly rarely, causing a severe bleeding tendency. The incidence is one in a million to one in five million people, with higher incidence in areas with consanguineous marriage such as Iran that has the highest global incidence of the disorder. Most are due to mutations...Read More

Alexander disease is a very rare autosomal dominant leukodystrophy, which are neurological conditions caused by anomalies in the myelin which protects nerve fibers in the brain. The most common type is the infantile form that usually begins during the first 2 years of life. Symptoms include mental...Read More

Progeria is a specific type of progeroid syndrome, also known as Hutchinson-Gilford syndrome. Progeroid syndromes are a group of diseases that cause victims to age faster than usual, leading to them appearing older than they are. Patients born with progeria typically live to an age of mid-teens to early twenties.Severe cardiovascular complications usually develop by puberty, resulting in death.

Creutzfeldt–Jakob disease (CJD), also known as subacute spongiform encephalopathy or neurocognitive disorder due to prion disease, is a fatal degenerative brain disorder. Early symptoms include memory problems, behavioral changes, poor coordination, and visual disturbances. Later symptoms include...Read More

Barth syndrome (BTHS) is an X-linked genetic disorder. The disorder, which affects multiple body systems, is diagnosed almost exclusively in males. It is named after Dutch pediatric neurologist Peter Barth.
Synonyms AGM2,Type 2 3-methylglutaconic aciduria,BTHS,Cardioskeletal myopathy – neutropenia

Glycogen storage disease type V (GSD5, GSD-V), also known as McArdle’s disease, is a metabolic disorder, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Its incidence is reported as one in 100,000, roughly the same as glycogen storage disease type I.The disease was first reported in 1951 by Dr. Brian McArdle of Guy’s Hospital, London.

Nephrogenic diabetes insipidus, also known as renal diabetes insipidus, is a form of diabetes insipidus primarily due to pathology of the kidney. This is in contrast to central or neurogenic diabetes insipidus, which is caused by insufficient levels of antidiuretic hormone (also called vasopressin)....Read More

Congenital generalized lipodystrophy (also known as Berardinelli–Seip lipodystrophy) is an extremely rare autosomal recessive condition, characterized by an extreme scarcity of fat in the subcutaneous tissues. It is a type of lipodystophy disorder where the magnitude of fat loss determines the severity of metabolic complications. Only 250 cases of the condition have been reported, and it is estimated that it occurs in 1 in 10 million people worldwide.

Fibrolamellar hepatocellular carcinoma (FHCC) is a rare form of hepatocellular carcinoma (HCC) that typically affects young adults and is characterized, under the microscope, by laminated fibrous layers interspersed between the tumour cells. Approximately 200 new cases are diagnosed worldwide each year.

Autoimmune polyendocrine syndrome type 1 (APS-1), is a subtype of autoimmune polyendocrine syndrome (autoimmune polyglandular syndrome). It causes the dysfunction of multiple endocrine glands due to autoimmunity. It is a genetic disorder, inherited in autosomal recessive fashion due to a defect in the AIRE gene (autoimmune regulator), which is located on chromosome 21 and normally confers immune tolerance.

Cerebral creatine deficiencies are a small group of inherited disorders that result from defects in creatine biosynthesis and utilization. Commonly affected tissues include the brain and muscles. There are three distinct CCDs. The most common is creatine transporter defect (CTD), an X-linked disorder...Read More

Cyclic neutropenia (CyN) is a rare hematologic disorder and form of congenital neutropenia that tends to occur approximately every three weeks and lasting for few days at a time due to changing rates of neutrophil production by the bone marrow. It causes a temporary condition with a low absolute neutrophil...Read More

The goblet cell carcinoid (GCC) is a rare biphasic gastrointestinal tract tumour that consists of a neuroendocrine component and a conventional carcinoma, histologically arising from Paneth cells.

Ablepharon macrostomia syndrome (AMS) is an extremely rare, autosomal dominant genetic disorder characterized by abnormal phenotypic appearances that primarily affect the head and face as well as the skull, skin, fingers and genitals. AMS generally results in abnormal ectoderm-derived structures....Read More

Baller–Gerold syndrome (BGS) is a rare genetic syndrome that involves premature fusion of the skull bones and malformations of facial, forearm and hand bones. The symptoms of Baller–Gerold syndrome overlap with features of a few other genetics disorders: Rothmund–Thomson syndrome and RAPADILINO...Read More

Bernard–Soulier syndrome (BSS), is a rare autosomal recessive bleeding disorder that is caused by a deficiency of the glycoprotein Ib-IX-V complex (GPIb-IX-V), the receptor for von Willebrand factor. The incidence of BSS is estimated to be less than 1 case per million persons, based on cases reported from Europe, North America, and Japan. BSS is a giant platelet disorder, meaning that it is characterized by abnormally large platelets.

Caroli disease (communicating cavernous ectasia, or congenital cystic dilatation of the intrahepatic biliary tree) is a rare inherited disorder characterized by cystic dilatation (or ectasia) of the bile ducts within the liver. There are two patterns of Caroli disease: focal or simple Caroli disease...Read More

Cleidocranial dysostosis (CCD), also called cleidocranial dysplasia, is a birth defect that mostly affects the bones and teeth. The collarbones are typically either poorly developed or absent, which allows the shoulders to be brought close together. The front of the skull often does not close until...Read More

Cold agglutinin disease (CAD) is a rare autoimmune disease characterized by the presence of high concentrations of circulating cold sensitive antibodies, usually IgM and autoantibodies that are also active at temperatures below 30 °C (86 °F), directed against red blood cells, causing them to agglutinate...Read More

Congenital afibrinogenemia is a rare, genetically inherited blood fibrinogen disorder in which the blood does not clot normally due to the lack of fibrinogen, a blood protein necessary for coagulation. This disorder is autosomal recessive, meaning that two unaffected parents can have a child with the disorder. The lack of fibrinogen expresses itself with excessive and, at times, uncontrollable bleeding.

Cutaneous T cell lymphoma (CTCL) is a class of non-Hodgkin lymphoma, which is a type of cancer of the immune system. Unlike most non-Hodgkin lymphomas (which are generally B cell related), CTCL is caused by a mutation of T cells. The cancerous T cells in the body initially migrate to the skin, causing...Read More

Cutis laxa or pachydermatocele is a group of rare connective tissue disorders in which the skin becomes inelastic and hangs loosely in folds.

Factor XI or plasma thromboplastin antecedent is the zymogen form of factor XIa, one of the enzymes of the coagulation cascade. Like many other coagulation factors, it is a serine protease. In humans, Factor XI is encoded by the F11 gene.

Factor XII deficiency is a deficiency in the production of factor XII (FXII), a plasma glycoprotein and clotting factor that participates in the coagulation cascade and activates factor XI. FXII appears to be not essential for blood clotting, as individuals with this condition are usually asymptomatic and form blood clots in vivo. FXII deficiency tends to be identified during presurgical laboratory screening for bleeding disorders.The condition can be inherited or acquired.

Familial partial lipodystrophy, also known as Köbberling–Dunnigan syndrome, is a rare genetic metabolic condition characterized by the loss of subcutaneous fat.: 495 FPL also refers to a rare metabolic condition in which there is a loss of subcutaneous fat in the arms, legs and lower torso....Read More

Fatal insomnia is an extremely rare genetic disorder that results in trouble sleeping as its hallmark symptom. The problems with sleeping typically start out gradually and worsen over time. Other symptoms may include speech problems, coordination problems, and dementia. It results in death within...Read More

Glycogen storage disease type VI (GSD VI) is a type of glycogen storage disease caused by a deficiency in liver glycogen phosphorylase or other components of the associated phosphorylase cascade system. It is also known as “Hers’ disease”, after Henri G. Hers, who characterized it...Read More

Hypothalamic disease is a disorder presenting primarily in the hypothalamus, which may be caused by damage resulting from malnutrition, including anorexia and bulimia eating disorders, genetic disorders, radiation, surgery, head trauma, lesion, tumour or other physical injury to the hypothalamus....Read More

Obesity is a medical condition in which excess body fat has accumulated to an extent that it may have a negative effect on health. People are generally considered obese when their body mass index (BMI), a measurement obtained by dividing a person’s weight by the square of the person’s...Read More

Keratosis follicularis spinulosa decalvans is a rare X-linked disorder described by Siemens in 1926, a disease that begins in infancy with keratosis pilaris localized on the face, then evolves to more diffuse involvement.: 580, 762 : 649, 714 An association with SAT1 has been suggested.

Miller syndrome, also known as Genée–Wiedemann syndrome, Wildervanck–Smith syndrome or postaxial acrofacial dystosis, is an extremely rare genetic condition that manifests as craniofacial, limb and eye deformities. It is caused by a mutation in the DHODH gene. The incidence of the condition is not known, and nothing is known of its pathogenesis.

Opsoclonus myoclonus syndrome (OMS), also known as opsoclonus-myoclonus-ataxia (OMA), is a rare neurological disorder of unknown cause which appears to be the result of an autoimmune process involving the nervous system. It is an extremely rare condition, affecting as few as 1 in 10,000,000 people per year. It affects 2 to 3% of children with neuroblastoma and has been reported to occur with celiac disease and diseases of neurologic and autonomic dysfunction

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, life-threatening disease of the blood characterized by destruction of red blood cells by the complement system, a part of the body’s innate immune system. This destructive process occurs due to deficiency of the red blood cell surface...Read More

Crigler–Najjar syndrome is a rare inherited disorder affecting the metabolism of bilirubin, a chemical formed from the breakdown of the heme in red blood cells. The disorder results in a form of nonhemolytic jaundice, which results in high levels of unconjugated bilirubin and often leads to brain...Read More

Cardiofaciocutaneous (CFC) syndrome is an extremely rare genetic disorder, and is one of the RASopathies. It was first described in 1986.It is characterized by the following:

Distinctive facial appearance
Unusually sparse, brittle, curly scalp hair
A range of skin abnormalities...Read More

Factor X deficiency (X as Roman numeral ten) is a bleeding disorder characterized by a lack in the production of factor X (FX), an enzyme protein that causes blood to clot in the coagulation cascade. Produced in the liver FX when activated cleaves prothrombin to generate thrombin in the intrinsic pathway of coagulation. This process is vitamin K dependent and enhanced by activated factor V.
The condition may be inherited or, more commonly, acquired.

Acquired haemophilia A (AHA) is a rare but potentially life-threatening bleeding disorder characterized by autoantibodies directed against coagulation factor VIII. These autoantibodies constitute the most common spontaneous inhibitor to any coagulation factor and may induce spontaneous bleeding in...Read More

Appendix cancer are very rare cancers of the vermiform appendix.
Gastrointestinal stromal tumors are rare tumors with malignant potential. Primary lymphomas can occur in the appendix. Breast cancer, colon cancer, and tumors of the female genital tract may metastasize to the appendix.

A craniopharyngioma is a rare type of brain tumor derived from pituitary gland embryonic tissue that occurs most commonly in children, but also affects adults. It may present at any age, even in the prenatal and neonatal periods, but peak incidence rates are childhood-onset at 5–14 years and adult-onset...Read More

Argininemia, is an autosomal recessive urea cycle disorder where a deficiency of the enzyme arginase causes a buildup of arginine and ammonia in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if levels become too high; the nervous system is especially sensitive to the effects of excess ammonia.

Aplastic anemia is a disease in which the body fails to produce blood cells in sufficient numbers. Blood cells are produced in the bone marrow by stem cells that reside there. Aplastic anaemia causes a deficiency of all blood cell types: red blood cells, white blood cells, and platelets.It occurs...Read More

Bardet–Biedl syndrome (BBS) is a ciliopathic human genetic disorder that produces many effects and affects many body systems. It is characterized by rod/cone dystrophy, polydactyly, central obesity, hypogonadism, and kidney dysfunction in some cases. Historically, slower mental processing has also been considered a principal symptom but is now not regarded as such.

Glomerulonephritis (GN) is a term used to refer to several kidney diseases (usually affecting both kidneys). Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the name, but not all diseases necessarily have an inflammatory...Read More

Hereditary sensory and autonomic neuropathy (HSAN) or hereditary sensory neuropathy (HSN) is a condition used to describe any of the types of this disease which inhibit sensation.
They are less common than Charcot-Marie-Tooth disease.

Hyper IgM syndrome describes a group of primary immune deficiency disorders characterized by defective CD40 signaling; via B cells affecting class switch recombination (CSR) and somatic hypermutation. Immunoglobulin (Ig) class switch recombination deficiencies are characterized by elevated serum Immunoglobulin...Read More

Hyperprolinemia is a condition which occurs when the amino acid proline is not broken down properly by the enzymes proline oxidase or pyrroline-5-carboxylate dehydrogenase, causing a buildup of proline in the body.

Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as allergic granulomatosis, is an extremely rare autoimmune condition that causes inflammation of small and medium-sized blood vessels (vasculitis) in persons with a history of airway allergic hypersensitivity (atopy).It usually...Read More

Takayasu’s arteritis (TA), also known as aortic arch syndrome, nonspecific aortoarteritis, and pulseless disease,: 841  is a form of large vessel granulomatous vasculitis with massive intimal fibrosis and vascular narrowing, most commonly affecting young or middle-age women of Asian descent,...Read More

Factor VII deficiency is a bleeding disorder characterized by a lack in the production of Factor VII (FVII) (proconvertin), a protein that causes blood to clot in the coagulation cascade. After a trauma factor VII initiates the process of coagulation in conjunction with tissue factor (TF/factor III) in the extrinsic pathway.
The condition may be inherited or acquired. It is the most common of the rare congenital coagulation disorders.

Guanidinoacetate methyltransferase deficiency (GAMT deficiency), is an autosomal recessive cerebral creatine deficiency that primarily affects the nervous system and muscles. It is the first described disorder of creatine metabolism, and results from deficient activity of guanidinoacetate methyltransferase,...Read More

Dermatomyositis (DM) is a long-term inflammatory disorder which affects skin and the muscles. Its symptoms are generally a skin rash and worsening muscle weakness over time. These may occur suddenly or develop over months. Other symptoms may include weight loss, fever, lung inflammation, or light...Read More

Acid sphingomyelinase is one of the enzymes that make up the sphingomyelinase (SMase) family, responsible for catalyzing the breakdown of sphingomyelin to ceramide and phosphorylcholine. They are organized into alkaline, neutral, and acidic SMase depending on the pH in which their enzymatic activity...Read More

Alkaptonuria is a rare inherited genetic disease which is caused by a mutation in the HGD gene for the enzyme homogentisate 1,2-dioxygenase (EC 1.13.11.5); if a person inherits an abnormal copy from both parents (it is a recessive condition), the body accumulates an intermediate substance called homogentisic...Read More

Bladder exstrophy is a congenital anomaly that exists along the spectrum of the exstrophy-epispadias complex, and most notably involves protrusion of the urinary bladder through a defect in the abdominal wall. Its presentation is variable, often including abnormalities of the bony pelvis, pelvic...Read More

An epispadias is a rare type of malformation in which the urethra ends, in males, in an opening on the upper aspect of the penis, and in females when the urethra develops too far anteriorly. It occurs in around 1 in 120,000 male and 1 in 500,000 female births.

Lipoprotein lipase deficiency is a genetic disorder in which a person has a defective gene for lipoprotein lipase, which leads to very high triglycerides, which in turn causes stomach pain and deposits of fat under the skin, and which can lead to problems with the pancreas and liver, which in turn...Read More

Mitochondrial DNA depletion syndrome (MDS or MDDS), or Alper’s disease, is any of a group of autosomal recessive disorders that cause a significant drop in mitochondrial DNA in affected tissues. Symptoms can be any combination of myopathic, hepatopathic, or encephalomyopathic. These syndromes...Read More

Familial hypercholesterolemia (FH) is a genetic disorder characterized by high cholesterol levels, specifically very high levels of low-density lipoprotein (LDL, “bad cholesterol”), in the blood and early cardiovascular disease. The most common mutations diminish the number of functional...Read More

Infantile neuronal ceroid lipofuscinoses (INCL) or Santavuori disease or Hagberg-Santavuori disease or Santavuori-Haltia disease or Infantile Finnish type neuronal ceroid lipofuscinosis or Balkan disease is a form of NCL and inherited as a recessive autosomal genetic trait. The disorder is progressive,...Read More

Diamond–Blackfan anemia (DBA) is a congenital erythroid aplasia that usually presents in infancy. DBA causes low red blood cell counts (anemia), without substantially affecting the other blood components (the platelets and the white blood cells), which are usually normal. This is in contrast to...Read More

Conradi–Hünermann syndrome is a rare type of chondrodysplasia punctata. It is associated with the EBP gene and affects between one in 100,000 and one in 200,000 babies.

Cystinosis is a lysosomal storage disease characterized by the abnormal accumulation of cystine, the oxidized dimer of the amino acid cysteine. It is a genetic disorder that follows an autosomal recessive inheritance pattern. It is a rare autosomal recessive disorder resulting from accumulation of...Read More

Argininosuccinic aciduria, is an inherited disorder that causes the accumulation of argininosuccinic acid (also known as “ASA”) in the blood and urine. Some patients may also have an elevation of ammonia, a toxic chemical, which can affect the nervous system. Argininosuccinic aciduria...Read More

Fanconi anaemia (FA) is a rare genetic disease resulting in impaired response to DNA damage. Although it is a very rare disorder, study of this and other bone marrow failure syndromes has improved scientific understanding of the mechanisms of normal bone marrow function and development of cancer....Read More

Asphyxiating thoracic dysplasia (ATD), also known as Jeune syndrome, is a rare inherited bone growth disorder (autosomal recessive skeletal dysplasia) that primarily affects the thoracic region. It was first described in 1955 by the French pediatrician Mathis Jeune. Common signs and symptoms can include...Read More

Erythropoietic protoporphyria (or commonly called EPP) is a form of porphyria, which varies in severity and can be very painful. It arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the red blood cells (erythrocytes), plasma, skin, and liver. The severity varies significantly from individual to individual.
A clinically similar form of porphyria, known as X-Linked dominant protoporphyria, was identified in 2008.

Orofaciodigital syndrome or oral-facial-digital syndrome is a group of at least 13 related conditions that affect the development of the mouth, facial features, and digits in between 1 in 50,000 to 250,000 newborns with the majority of cases being type I (Papillon-League-Psaume syndrome).

Abetalipoproteinemia (also known as: Bassen-Kornzweig syndrome, microsomal triglyceride transfer protein deficiency disease, MTP deficiency, and betalipoprotein deficiency syndrome) is a disorder that interferes with the normal absorption of fat and fat-soluble vitamins from food. It is caused by...Read More

A vestibular schwannoma (VS), also called acoustic neuroma, is a benign tumor that develops on the vestibulocochlear nerve that passes from the inner ear to the brain. The tumor originates when Schwann cells that form the insulating myelin sheath on the nerve malfunction. Normally, Schwann cells function...Read More

Arteriovenous malformation is an abnormal connection between arteries and veins, bypassing the capillary system. This vascular anomaly is widely known because of its occurrence in the central nervous system (usually cerebral AVM), but can appear in any location. Although many AVMs are asymptomatic,...Read More

Bartter syndrome (BS) is a rare inherited disease characterised by a defect in the thick ascending limb of the loop of Henle, which results in low potassium levels (hypokalemia), increased blood pH (alkalosis), and normal to low blood pressure. There are two types of Bartter syndrome: neonatal and classic. A closely associated disorder, Gitelman syndrome, is milder than both subtypes of Bartter syndrome.

Beta thalassemias (β thalassemias) are a group of inherited blood disorders. They are forms of thalassemia caused by reduced or absent synthesis of the beta chains of hemoglobin that result in variable outcomes ranging from severe anemia to clinically asymptomatic individuals. Global annual incidence...Read More

Cat eye syndrome (CES) or Schmid–Fraccaro syndrome is a rare condition caused by an abnormal extra chromosome, i.e. a small supernumerary marker chromosome. This chromosome consists of the entire short arm and a small section of the long arm of chromosome 22. In consequence, individuals with the...Read More

Cholangiocarcinoma, also known as bile duct cancer, is a type of cancer that forms in the bile ducts. Symptoms of cholangiocarcinoma may include abdominal pain, yellowish skin, weight loss, generalized itching, and fever. Light colored stool or dark urine may also occur. Other biliary tract cancers...Read More

Chromosomal deletion syndromes result from deletion of parts of chromosomes. Depending on the location, size, and whom the deletion is inherited from, there are a few known different variations of chromosome deletions. Chromosomal deletion syndromes typically involve larger deletions that are visible...Read More

Dentin dysplasia (DD) is a rare genetic developmental disorder affecting dentine production of the teeth, commonly exhibiting an autosomal dominant inheritance that causes malformation of the root. It affects both primary and permanent dentitions in approximately 1 in every 100,000 patients. It is...Read More

Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development. This condition is a type of dentin dysplasia that causes teeth to be discolored (most often a blue-gray or yellow-brown color) and translucent giving teeth an opalescent sheen. Although genetic factors are the main contributor...Read More

Epidermolytic ichthyosis (EI), also known as bullous epidermis ichthyosis (BEI), epidermolytic hyperkeratosis (EHK), bullous congenital ichthyosiform erythroderma (BCIE), bullous ichthyosiform erythroderma: 482  or bullous congenital ichthyosiform erythroderma Brocq, is a rare and severe form...Read More

Essential thrombocythemia (ET) is a rare chronic blood cancer (myeloproliferative neoplasm) characterised by the overproduction of platelets (thrombocytes) by megakaryocytes in the bone marrow. It may, albeit rarely, develop into acute myeloid leukemia or myelofibrosis. It is one of four myeloproliferative neoplasms (blood cancers) that occur when the body makes too many white or red blood cells, or platelets).

Glycogen storage disease type I (GSD I) is an inherited disease that results in the liver being unable to properly break down stored glycogen. This impairment disrupts the liver’s ability to break down stored glycogen that is necessary to maintain adequate blood sugar levels. GSD I is divided...Read More

Meleda disease (MDM) or “mal de Meleda”, also called Mljet disease, keratosis palmoplantaris and transgradiens of Siemens, (also known as “acral keratoderma”, “mutilating palmoplantar keratoderma of the Gamborg-Nielsen type”, “palmoplantar ectodermal dysplasia...Read More

Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis (also termed meningococcus). It has a high mortality rate if untreated but is vaccine-preventable. While best known as a cause of meningitis, it can also result in sepsis, which is an even more damaging and dangerous...Read More

Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion or altered consciousness, vomiting, and an inability to tolerate...Read More

MERRF syndrome (or myoclonic epilepsy with ragged red fibers) is a mitochondrial disease. It is extremely rare, and has varying degrees of expressivity owing to heteroplasmy. MERRF syndrome affects different parts of the body, particularly the muscles and nervous system. The signs and symptoms of...Read More

Acrocallosal syndrome (also known as ACLS) is an extremely rare autosomal recessive syndrome characterized by corpus callosum agenesis, polydactyly, multiple dysmorphic features, motor and intellectual disabilities, and other symptoms. The syndrome was first described by Albert Schinzel in 1979. Mutations in KIF7 are causative for ACLS, and mutations in GLI3 are associated with a similar syndrome.

Acrodermatitis enteropathica is an autosomal recessive metabolic disorder affecting the uptake of zinc through the inner lining of the bowel, the mucous membrane. It is characterized by inflammation of the skin (dermatitis) around bodily openings (periorificial) and the tips of fingers and toes (acral),...Read More

Acromesomelic dysplasia is a rare skeletal disorder that causes abnormal bone and cartilage development, leading to shortening of the forearms, lower legs, hands, feet, fingers, and toes. Five different genetic mutations have been implicated in the disorder. Treatment is individualized but is generally aimed at palliating symptoms, for example, treatment of kyphosis and lumbar hyperlordosis.

Eosinophilic pneumonia is a disease in which an eosinophil, a type of white blood cell, accumulates in the lungs. These cells cause disruption of the normal air spaces (alveoli) where oxygen is extracted from the atmosphere. Several different kinds of eosinophilic pneumonia exist and can occur in...Read More

Acute intermittent porphyria (AIP) is a rare metabolic disorder affecting the production of heme resulting from a deficiency of the porphobilinogen deaminase. It is the most common of the acute porphyrias.

Acute promyelocytic leukemia (APML, APL) is a subtype of acute myeloid leukemia (AML), a cancer of the white blood cells. In APL, there is an abnormal accumulation of immature granulocytes called promyelocytes. The disease is characterized by a chromosomal translocation involving the retinoic acid...Read More

Neuronal ceroid lipofuscinosis is the general name for a family of at least eight genetically separate neurodegenerative lysosomal storage diseases that result from excessive accumulation of lipopigments (lipofuscin) in the body’s tissues. These lipopigments are made up of fats and proteins....Read More

Adult polyglucosan body disease (APBD) is an orphan disease and a glycogen storage disorder that is caused by an inborn error of metabolism. Symptoms can emerge any time after the age of 30; early symptoms include trouble controlling urination, trouble walking, and lack of sensation in the legs....Read More

Hay–Wells syndrome (also known as AEC syndrome; see Naming) is one of at least 150 known types of ectodermal dysplasia. These disorders affect tissues that arise from the ectodermal germ layer, such as skin, hair, and nails.

Alpha-thalassemia (α-thalassemia, α-thalassaemia) is a form of thalassemia involving the genes HBA1 and HBA2. Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. Normal hemoglobin consists of...Read More

Alpha-1 antitrypsin deficiency (A1AD or AATD) is a genetic disorder that may result in lung disease or liver disease. Onset of lung problems is typically between 20 and 50 years of age. This may result in shortness of breath, wheezing, or an increased risk of lung infections. Complications may include...Read More

Alpha-mannosidosis is a lysosomal storage disorder, first described by Swedish physician Okerman in 1967. In humans it is known to be caused by an autosomal recessive genetic mutation in the gene MAN2B1, located on chromosome 19, affecting the production of the enzyme alpha-D-mannosidase, resulting...Read More

Alström syndrome (AS), also called Alström–Hallgren syndrome, is a very rare autosomal recessive genetic disorder characterised by childhood obesity and multiple organ dysfunction. Symptoms include early-onset type 2 diabetes, cone-rod dystrophy resulting in blindness, sensorineural hearing loss...Read More

Alternating hemiplegia of childhood is an ultra-rare neurological disorder named for the transient episodes, often referred to as “attacks”, of hemiplegia (weakness or paralysis) from which those with the disorder suffer. It typically presents before the age of 18 months. These hemiplegic...Read More

Amyloidosis is a group of diseases in which abnormal proteins, known as amyloid fibrils, build up in tissue. There are several non-specific and vague signs and symptoms associated with amyloidosis. These include: fatigue, peripheral edema, weight loss, shortness of breath, palpitations, and feeling...Read More

Antley–Bixler syndrome, is a rare, very severe autosomal recessive congenital disorder characterized by malformations and deformities affecting the majority of the skeleton and other areas of the body.

Cockayne syndrome (CS), also called Neill-Dingwall syndrome, is a rare and fatal autosomal recessive neurodegenerative disorder characterized by growth failure, impaired development of the nervous system, abnormal sensitivity to sunlight (photosensitivity), eye disorders and premature aging. Failure...Read More

Chordoma is a rare slow-growing neoplasm thought to arise from cellular remnants of the notochord. The evidence for this is the location of the tumors (along the neuraxis), the similar immunohistochemical staining patterns, and the demonstration that notochordal cells are preferentially left behind in the clivus and sacrococcygeal regions when the remainder of the notochord regresses during fetal life.
In layman’s terms, chordoma is a type of spinal cancer.

Jacobsen syndrome is a rare chromosomal disorder resulting from deletion of genes from chromosome 11 that includes band 11q24.1. It is a congenital disorder. Since the deletion takes place on the q arm of chromosome 11, it is also called 11q terminal deletion disorder. The deletion may range from...Read More

Cockayne syndrome (CS), also called Neill-Dingwall syndrome, is a rare and fatal autosomal recessive neurodegenerative disorder characterized by growth failure, impaired development of the nervous system, abnormal sensitivity to sunlight (photosensitivity), eye disorders and premature aging. Failure...Read More

Congenital fibrosis of the extraocular muscles, is a class of rare genetic disorders affecting one or more of the muscles that move the eyeballs. Individuals with CFEOM have varying degrees of ophthalmoplegia (an inability to move the eyes in one or more directions) and ptosis. The condition is present...Read More

Congenital muscular dystrophies are autosomal recessively-inherited muscle diseases. They are a group of heterogeneous disorders characterized by muscle weakness which is present at birth and the different changes on muscle biopsy that ranges from myopathic to overtly dystrophic due to the age at which the biopsy takes place.

Hypoplasminogenemia, also known as plasminogen deficiency type 1, is a genetic disorder characterized by a lack of the protein plasminogen, which is responsible for the ability of the body to break down fibrin clots. Plasminogen deficiency leads to an accumulation of fibrin, causing the development of growths (lesions) that can impair normal tissue and organ function and may lead to blindness when these lesions affect the eyes.It is caused by mutations in the PLG gene.

Trevor disease, also known as dysplasia epiphysealis hemimelica and Trevor’s disease, is a congenital bone developmental disorder. There is 1 case per million population. The condition is three times more common in males than in females.

Emery–Dreifuss muscular dystrophy (EDMD) is a type of muscular dystrophy, a group of heritable diseases that cause progressive impairment of muscles. EDMD affects muscles used for movement (skeletal muscles), causing atrophy, weakness and contractures. It almost always affects the heart, causing abnormal rhythms, heart failure, or sudden cardiac death.
It is rare, affecting 0.39 per 100,000 (1 per 250,000) people. It is named after Alan Eglin H. Emery and Fritz E. Dreifuss.

Ewing sarcoma is a type of cancer that may be a bone sarcoma or a soft-tissue sarcoma. Symptoms may include swelling and pain at the site of the tumor, fever, and a bone fracture. The most common areas where it begins are the legs, pelvis, and chest wall. In about 25% of cases, the cancer has already...Read More

Focal segmental glomerulosclerosis (FSGS), also known as “focal glomerular sclerosis” or “focal nodular glomerulosclerosis,” is a histopathologic finding of scarring (sclerosis) of glomeruli and damage to renal podocytes. This process damages the filtration function of the kidney, resulting...Read More

Fraser syndrome (also known as Meyer-Schwickerath’s syndrome, Fraser-François syndrome, or Ullrich-Feichtiger syndrome) is an autosomal recessive congenital disorder, identified by several developmental anomalies. Fraser syndrome is named for the geneticist George R. Fraser, who first described the syndrome in 1962.

Fucosidosis is a rare lysosomal storage disorder in which the FUCA1 gene experiences mutations that severely reduce or stop the activity of the alpha-L-fucosidase enzyme. The result is a buildup of complex sugars in parts of the body, which leads to death.
Fucosidosis is one of nine identified glycoprotein storage diseases. The gene encoding the alpha-fucosidase, FUCA 1, was found to be located to the short arm of chromosome 1p36 – p34, by Carrit and co-workers, in 1982.

Pelizaeus–Merzbacher disease is an X-linked neurological disorder that damages oligodendrocytes in the central nervous system. It is caused by mutations in proteolipid protein 1 (PLP1), a major myelin protein. It is characterized by a decrease in the amount of insulating myelin surrounding the nerves (hypomyelination) and belongs to a group of genetic diseases referred to as leukodystrophies.

Parry–Romberg syndrome (PRS) is a rare disease characterized by progressive shrinkage and degeneration of the tissues beneath the skin, usually on only one side of the face (hemifacial atrophy) but occasionally extending to other parts of the body. An autoimmune mechanism is suspected, and the syndrome...Read More

Paramyotonia congenita (PC), is a rare congenital autosomal dominant neuromuscular disorder characterized by “paradoxical” myotonia. This type of myotonia has been termed paradoxical because it becomes worse with exercise whereas classical myotonia, as seen in myotonia congenita, is alleviated...Read More

Ollier disease is a rare sporadic nonhereditary skeletal disorder in which typically benign cartilaginous tumors (enchondromas) develop near the growth plate cartilage. This is caused by cartilage rests that grow and reside within the metaphysis or diaphysis and eventually mineralize over time to...Read More

Oculopharyngeal muscular dystrophy (OPMD) is a rare form of muscular dystrophy with symptoms generally starting when an individual is 40 to 50 years old. It can be autosomal dominant neuromuscular disease or autosomal recessive. The most common inheritance of OPMD is autosomal dominant, which means...Read More

Niemann–Pick type C (NPC) (colloquially, “Childhood Alzheimer’s”) is a lysosomal storage disease associated with mutations in NPC1 and NPC2 genes. Niemann–Pick type C affects an estimated 1:150,000 people. Approximately 50% of cases present before 10 years of age, but manifestations may first be recognized as late as the sixth decade.

Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep-wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affected also experience episodes of sudden loss of muscle strength,...Read More

Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by autonomic dysfunction, tremors, slow movement, muscle rigidity, and postural instability (collectively known as parkinsonism) and ataxia. This is caused by progressive degeneration of neurons in several parts of the...Read More

Multifocal motor neuropathy (MMN) is a progressively worsening condition where muscles in the extremities gradually weaken. The disorder, a pure motor neuropathy syndrome, is sometimes mistaken for amyotrophic lateral sclerosis (ALS) because of the similarity in the clinical picture, especially if...Read More

Mucormycosis, also known as black fungus, is a serious fungal infection, usually in people who are immunocompromised. Symptoms depend on where in the body the infection occurs. It most commonly infects the nose, sinuses, eye, and brain resulting in a runny nose, one-sided facial swelling and pain,...Read More

Sly syndrome, also called mucopolysaccharidosis type VII (MPS-VII), is an autosomal recessive lysosomal storage disease caused by a deficiency of the enzyme β-glucuronidase. This enzyme is responsible for breaking down large sugar molecules called glycosaminoglycans (AKA GAGs, or mucopolysaccharides). The inability to break down GAGs leads to a buildup in many tissues and organs of the body. The severity of the disease can vary widely.

Sanfilippo syndrome, also known as mucopolysaccharidosis type III (MPS III), is a rare autosomal recessive lysosomal storage disease that primarily affects the brain and spinal cord. It is caused by a buildup of large sugar molecules called glycosaminoglycans (AKA GAGs, or mucopolysaccharides) in...Read More

Hunter syndrome, or mucopolysaccharidosis type II (MPS II), is a rare genetic disorder in which large sugar molecules called glycosaminoglycans (or GAGs or mucopolysaccharides) build up in body tissues. It is a form of lysosomal storage disease. Hunter syndrome is caused by a deficiency of the lysosomal...Read More

Mucopolysaccharidosis type I is a spectrum of diseases in the mucopolysaccharidosis family. It results in the buildup of glycosaminoglycans (or GAGs, or mucopolysaccharides) due to a deficiency of alpha-L iduronidase, an enzyme responsible for the degradation of GAGs in lysosomes. Without this enzyme,...Read More

Morquio syndrome, also known as Mucopolysaccharidosis Type IV (MPS IV), is a rare metabolic disorder in which the body cannot process certain types of sugar molecules called glycosaminoglycans (AKA GAGs, or mucopolysaccharides). In Morquio syndrome, the specific GAG which builds up in the body is...Read More

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. GISTs arise in the smooth muscle pacemaker interstitial cell of Cajal, or similar cells. They are defined as tumors whose behavior is driven by mutations in the KIT gene (85%), PDGFRA...Read More

Generalized arterial calcification of infancy (GACI) is an extremely rare genetic disorder. It is caused by mutations in the ENPP1 gene in 75% of the subjects or in mutations in the ABCC6 genes in 10% of patients. However, sometimes individuals affected with GACI do not have mutations in the ENPP1...Read More

Gerstmann–Sträussler–Scheinker syndrome (GSS) is an extremely rare, usually familial, fatal neurodegenerative disease that affects patients from 20 to 60 years in age. It is exclusively heritable, and is found in only a few families all over the world. It is, however, classified with the transmissible...Read More

Giant cell arteritis (GCA), also called temporal arteritis, is an inflammatory autoimmune disease of large blood vessels. Symptoms may include headache, pain over the temples, flu-like symptoms, double vision, and difficulty opening the mouth. Complication can include blockage of the artery to the...Read More

Glutaric acidemia type 1 is an inherited disorder in which the body is unable to completely break down the amino acids lysine, hydroxylysine and tryptophan. Excessive levels of their intermediate breakdown products (glutaric acid, glutaryl-CoA, 3-hydroxyglutaric acid, glutaconic acid) can accumulate...Read More

Glutaric acidemia type 2 is an autosomal recessive metabolic disorder that is characterised by defects in the ability of the body to use proteins and fats for energy. Incompletely processed proteins and fats can build up, leading to a dangerous chemical imbalance called acidosis.

A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by an enzyme deficiency affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.GSD has two classes of cause: genetic and acquired. Genetic GSD is caused by any inborn error of metabolism (genetically defective enzymes) involved in these processes. In livestock, acquired GSD is caused by intoxication with the alkaloid castanospermine.

Glycogen storage disease type III (GSD III) is an autosomal recessive metabolic disorder and inborn error of metabolism (specifically of carbohydrates) characterized by a deficiency in glycogen debranching enzymes.It is also known as Cori’s disease in honor of the 1947 Nobel laureates Carl Cori...Read More

Glycogen storage disease type IX is a hereditary deficiency of glycogen phosphorylase kinase B that affects the liver and skeletal muscle tissue. It is inherited in an X-linked or autosomal recessive manner.

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide.It occurs in the setting of chronic liver inflammation, and is most closely...Read More

Orotic aciduria (AKA hereditary orotic aciduria) is a disease caused by an enzyme deficiency resulting in a decreased ability to synthesize pyrimidines. It was the first described enzyme deficiency of the de novo pyrimidine synthesis pathway.Orotic aciduria is characterized by excessive excretion of orotic acid in urine because of the inability to convert orotic acid to UMP. It causes megaloblastic anemia and may be associated with mental and physical developmental delays.

Holt–Oram syndrome (also called atrio-digital syndrome, atriodigital dysplasia, cardiac-limb syndrome, heart-hand syndrome type 1, HOS, ventriculo-radial syndrome) is an autosomal dominant disorder that affects bones in the arms and hands (the upper limbs) and often causes heart problems. The syndrome may include an absent radial bone in the forearm, an atrial septal defect in the heart, or heart block. It affects approximately 1 in 100,000 people.

Homocystinuria or HCU is an inherited disorder of the metabolism of the amino acid methionine due to a deficiency of cystathionine beta synthase or methionine synthase. It is an inherited autosomal recessive trait, which means a child needs to inherit a copy of the defective gene from both parents to be affected. Symptoms of homocystinuria can also be caused by a deficiency of vitamins B6, B12, or folate.

Hereditary haemochromatosis type 1 (HFE-related Hemochromatosis) is a genetic disorder characterized by excessive intestinal absorption of dietary iron, resulting in a pathological increase in total body iron stores. Humans, like most animals, have no means to excrete excess iron, with the exception...Read More

Hypophosphatasia (; also called deficiency of alkaline phosphatase, phosphoethanolaminuria, or Rathbun’s syndrome; sometimes abbreviated HPP) is a rare, and sometimes fatal, metabolic bone disease. Clinical symptoms are heterogeneous, ranging from the rapidly fatal, perinatal variant, with profound...Read More

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped and incapable of supporting the systemic circulation. It is estimated to account for 2-3% of all congenital heart disease. Early signs and symptoms include poor feeding,...Read More

A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended from a single mutated cell (monoclonality), as would typically...Read More

Idiopathic intracranial hypertension (IIH), previously known as pseudotumor cerebri and benign intracranial hypertension, is a condition characterized by increased intracranial pressure (pressure around the brain) without a detectable cause. The main symptoms are headache, vision problems, ringing...Read More

Incontinentia pigmenti (IP) is a rare X-linked dominant genetic disorder that affects the skin, hair, teeth, nails and central nervous system. It is named from its appearance under a microscope.The disease is characterized by skin abnormalities that begin in childhood, usually a blistering rash which...Read More

Infantile myofibromatosis (IMF) is a rare tumor found in 1 in 150,000 to 1 in 400,000 live births. It is nonetheless the most common tumor derived from fibrous connective tissue that occurs primarily in infants and young children. IMF tumors are benign in the sense that they do not metastasize to...Read More

Interferon regulatory factor 6 also known as IRF6 is a protein that in humans is encoded by the IRF6 gene.

Isovaleric acidemia is a rare autosomal recessive metabolic disorder which disrupts or prevents normal metabolism of the branched-chain amino acid leucine. It is a classical type of organic acidemia.

Jervell and Lange-Nielsen syndrome (JLNS) is a rare type of long QT syndrome associated with severe, bilateral sensorineural hearing loss. Those with JLNS are at risk of abnormal heart rhythms called arrhythmias, which can lead to fainting, seizures, or sudden death. JLNS, like other forms of long...Read More

Johanson–Blizzard syndrome is a rare, sometimes fatal autosomal recessive multisystem congenital disorder featuring abnormal development of the pancreas, nose and scalp, with intellectual disability, hearing loss and growth failure. It is sometimes described as a form of ectodermal dysplasia.The disorder is especially noted for causing profound developmental errors and exocrine dysfunction of the pancreas, and it is considered to be an inherited pancreatic disease.

Juvenile myelomonocytic leukemia (JMML) is a serious chronic leukemia (cancer of the blood) that affects children mostly aged 4 and younger. The name JMML now encompasses all diagnoses formerly referred to as juvenile chronic myeloid leukemia (JCML), chronic myelomonocytic leukemia of infancy, and...Read More

Kallmann syndrome (KS) is a genetic disorder that prevents a person from starting or fully completing puberty. Kallmann syndrome is a form of a group of conditions termed hypogonadotropic hypogonadism. To distinguish it from other forms of hypogonadotropic hypogonadism, Kallmann syndrome has the additional...Read More

Spinal and bulbar muscular atrophy (SBMA), popularly known as Kennedy’s disease, is a progressive debilitating neurodegenerative disorder resulting in muscle cramps and progressive weakness due to degeneration of motor neurons in the brainstem and spinal cord.The condition is associated with...Read More

Lambert–Eaton myasthenic syndrome (LEMS) is a rare autoimmune disorder characterized by muscle weakness of the limbs.
Around 60% of those with LEMS have an underlying malignancy, most commonly small-cell lung cancer; it is therefore regarded as a paraneoplastic syndrome (a condition that...Read More

Lamellar ichthyosis, also known as ichthyosis lamellaris and nonbullous congenital ichthyosis, is a rare inherited skin disorder, affecting around 1 in 600,000 people.

Langerhans cell histiocytosis (LCH) is an abnormal clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes.
Symptoms range from isolated bone lesions to multisystem disease. LCH is part of a group of syndromes called...Read More

Larsen syndrome (LS) is a congenital disorder discovered in 1950 by Larsen and associates when they observed dislocation of the large joints and face anomalies in six of their patients. Patients with Larsen syndrome normally present with a variety of symptoms, including congenital anterior dislocation...Read More

Laurence–Moon syndrome (LMS) is a rare autosomal recessive genetic disorder associated with retinitis pigmentosa, spastic paraplegia, and mental disabilities.

Lesch–Nyhan syndrome (LNS) is a rare inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). This deficiency occurs due to mutations in the HPRT1 gene located on the X chromosome. LNS affects about 1 in 380,000 live births. The disorder was...Read More

Leukodystrophies are a group of usually inherited disorders characterized by degeneration of the white matter in the brain. The word leukodystrophy comes from the Greek roots leuko, “white”, dys, “abnormal” and troph, “growth”. The leukodystrophies are caused by...Read More

Oculocerebrorenal syndrome (also called Lowe syndrome) is a rare X-linked recessive disorder characterized by congenital cataracts, hypotonia, intellectual disability, proximal tubular acidosis, aminoaciduria and low-molecular-weight proteinuria. Lowe syndrome can be considered a cause of Fanconi syndrome (bicarbonaturia, renal tubular acidosis, potassium loss and sodium loss).

Mantle cell lymphoma (MCL) is a type of non-Hodgkin’s lymphoma (NHL), comprising about 6% of NHL cases. There are only about 15,000 patients presently in the United States with mantle cell lymphoma. It is named for the mantle zone of the lymph nodes.
MCL is a subtype of B-cell lymphoma,...Read More

Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder affecting branched-chain amino acids. It is one type of organic acidemia. The condition gets its name from the distinctive sweet odor of affected infants’ urine, particularly prior to diagnosis and during times of acute illness.

McCune–Albright syndrome is a complex genetic disorder affecting the bone, skin and endocrine systems. It is a mosaic disease arising from somatic activating mutations in GNAS, which encodes the alpha-subunit of the Gs heterotrimeric G protein.It was first described in 1937 by American pediatrician Donovan James McCune and American endocrinologist Fuller Albright.

Primordial dwarfism (PD) is a form of dwarfism that results in a smaller body size in all stages of life beginning from before birth. More specifically, primordial dwarfism is a diagnostic category including specific types of profoundly proportionate dwarfism, in which individuals are extremely small...Read More

Melorheostosis is a medical developmental disorder and mesenchymal dysplasia in which the bony cortex widens and becomes hyperdense in a sclerotomal distribution. The condition begins in childhood and is characterized by thickening of the bones. Pain is a frequent symptom and the bone can have the appearance of dripping candle wax.

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer occurring in about 3 people per 1,000,000 members of the population. It is also known as cutaneous APUDoma, primary neuroendocrine carcinoma of the skin, primary small cell carcinoma of the skin, and trabecular carcinoma of the skin....Read More

Mesothelioma is a type of cancer that develops from the thin layer of tissue that covers many of the internal organs (known as the mesothelium). The most common area affected is the lining of the lungs and chest wall. Less commonly the lining of the abdomen and rarely the sac surrounding the heart,...Read More

Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation or pain often in the back along with muscle weakness, beginning in...Read More

Moyamoya disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots (thrombosis). A collateral circulation develops around the blocked vessels to compensate for the blockage, but the collateral vessels are small, weak, and prone...Read More

Febrile infection-related epilepsy syndrome (FIRES) is an epilepsy syndrome in which new-onset refractory status epilepticus (NORSE) is preceded by febrile illness 24 hours to 2 weeks prior to the onset of seizures. The term was previously used for a paediatric syndrome but was redefined to include...Read More

Cardiomyopathy is a group of diseases that affect the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. An irregular heart beat and fainting may occur. Those affected...Read More

Pancreatic neuroendocrine tumours (PanNETs, PETs, or PNETs), often referred to as “islet cell tumours”, or “pancreatic endocrine tumours” are neuroendocrine neoplasms that arise from cells of the endocrine (hormonal) and nervous system within the pancreas.
PanNETs are...Read More

Oto-palato-digital syndrome is the generalised term for two conditions, oto-palato-digital syndrome type I (OPD1) and oto-palato-digital syndrome type II (OPD2), that are both X-linked recessive genetic disorders with overlapping phenotypes. The most severe phenotypes of each syndrome occur only in...Read More

Uveal melanoma is a cancer (melanoma) of the eye involving the iris, ciliary body, or choroid (collectively referred to as the uvea). Tumors arise from the pigment cells (melanocytes) that reside within the uvea and give color to the eye. These melanocytes are distinct from the retinal pigment epithelium cells underlying the retina that do not form melanomas. When eye melanoma is spread to distant parts of the body, the five-year survival rate is about 15%.