Autoimmune & Inflammatory rare diseases14
Behçet Disease
Behçet Disease is a rare, chronic, recurrent vasculitis causing painful oral and genital ulcers, eye inflammation, and skin lesions.
3 drug guides
Dermatomyositis
Dermatomyositis is a rare autoimmune inflammatory disease causing muscle weakness and distinctive skin rashes, particularly over joints.
3 drug guides
Eosinophilic Granulomatosis with Polyangiitis
Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome) is a systemic necrotizing vasculitis characterized by asthma, blood eosinophilia, and inflammation of small- and medium-sized blood vessels.
2 drug guides
Giant Cell Arteritis
Giant Cell Arteritis is a rare inflammatory disease of large and medium-sized arteries, primarily affecting people over 50.
2 drug guides
Goodpasture Syndrome
Goodpasture syndrome is a rare autoimmune vasculitis affecting kidneys and lungs caused by autoantibodies against basement membrane.
Granulomatosis with Polyangiitis
Granulomatosis with Polyangiitis is a rare autoimmune disease causing inflammation of small and medium blood vessels in the lungs, kidneys, and upper respiratory tract.
IgG4-Related Disease
IgG4-related disease is a chronic fibroinflammatory condition characterized by tumor-like swelling in affected organs, dense lymphoplasmacytic infiltration rich in IgG4-positive plasma cells, storiform fibrosis, and often (but not always) elevated serum IgG4 levels.
1 drug guide|FDA decision May 27th, 2027
Mixed Connective Tissue Disease
Mixed connective tissue disease is a rare autoimmune disorder with features overlapping systemic lupus erythematosus, systemic sclerosis, and polymyositis.
Multiple SclerosisNot rare
Multiple sclerosis is a chronic autoimmune disease where the immune system attacks the protective myelin sheath surrounding nerve fibers in the brain and spinal cord.
13 drug guides
Neuromyelitis Optica
Neuromyelitis Optica (NMO) is a rare inflammatory autoimmune disorder of the central nervous system characterized by recurrent attacks of optic neuritis (vision loss) and acute myelitis (spinal cord inflammation) affecting motor and sensory function.
1 drug guide
Sjögren's SyndromeNot rare
Sjögren's syndrome is a chronic autoimmune disorder in which the immune system attacks the moisture-producing exocrine glands, primarily the salivary and lacrimal (tear) glands.
6 drug guides
Systemic Juvenile Idiopathic Arthritis
Systemic juvenile idiopathic arthritis is a severe autoinflammatory disease characterized by daily spiking fevers, a salmon-pink rash, and joint inflammation.
4 drug guides
Systemic Sclerosis
Systemic sclerosis (scleroderma) is a rare autoimmune disease in which the immune system triggers scarring (fibrosis) of the skin and internal organs while also damaging small blood vessels.
2 drug guides
Takayasu Arteritis
Takayasu Arteritis is a rare chronic inflammatory disease of large arteries, particularly the aorta and its branches, causing vessel narrowing, aneurysms, and aortic regurgitation.
Blood & Immune rare diseases31
Activated PI3K Delta Syndrome
Activated PI3K delta syndrome (APDS) is a rare inherited immune disorder in which an overactive enzyme keeps immune cells from working properly, causing repeated sinus and lung infections, swollen lymph nodes and a higher risk of lymphoma.
1 drug guide
Aplastic Anemia
Aplastic anemia is a rare bone marrow failure syndrome characterized by pancytopenia resulting from absent or severely reduced hematopoiesis.
4 drug guides
Chronic Graft-versus-Host Disease
Chronic graft-versus-host disease is an immune-mediated complication after allogeneic stem cell or bone marrow transplant, in which donor immune cells attack the recipient's tissues.
4 drug guides
Chronic Granulomatous Disease
Chronic granulomatous disease is a rare inherited immunodeficiency affecting the ability of neutrophils to produce reactive oxygen species.
1 drug guide
Cold Agglutinin Disease
Cold agglutinin disease is a rare autoimmune hemolytic anemia caused by IgM antibodies that stick to red blood cells in the cold.
1 drug guide
Common Variable Immunodeficiency
Common variable immunodeficiency is a primary immunodeficiency disorder characterized by low levels of immunoglobulins and impaired antibody responses.
Congenital Athymia
Congenital athymia is an ultra-rare condition in which a baby is born without a functioning thymus gland, the organ essential for developing T cells.
1 drug guide
Diamond-Blackfan Anemia
Diamond-Blackfan anemia is a rare inherited bone marrow failure syndrome characterized by selective reduction of red blood cell precursors.
Essential Thrombocythemia
Essential Thrombocythemia is a myeloproliferative neoplasm characterized by overproduction of platelets by bone marrow, resulting in very high platelet counts.
1 drug guide
Factor V Deficiency
Factor V deficiency is a rare inherited bleeding disorder caused by deficiency or dysfunction of coagulation factor V.
Fanconi Anemia
Fanconi anemia is a rare inherited bone marrow failure syndrome with cellular hypersensitivity to DNA crosslinking agents.
Hemophilia A
Hemophilia A is an X-linked bleeding disorder caused by deficiency or dysfunction of clotting factor VIII.
6 drug guides
Hemophilia B
Hemophilia B is an X-linked bleeding disorder caused by deficiency or dysfunction of clotting factor IX.
5 drug guides
Heparin-Induced Thrombocytopenia
Heparin-induced thrombocytopenia is a serious immune-mediated reaction to heparin, one of the most commonly used blood thinners in hospitals.
1 drug guide
Hereditary Angioedema
Hereditary Angioedema is a rare genetic disorder characterized by sudden, severe swelling (angioedema) of skin and mucous membranes affecting the face, hands, feet, gastrointestinal tract, and potentially the airway.
5 drug guides|FDA decision Mar 10th, 2027
Immune Thrombocytopenia
Immune thrombocytopenia (ITP) is a rare autoimmune disorder in which the immune system destroys platelets, the blood cells that stop bleeding, and slows their production.
6 drug guides
Light Chain Amyloidosis
Light Chain Amyloidosis is a rare, serious blood disorder caused by plasma cells producing misfolded immunoglobulin light chains that accumulate in tissues as amyloid fibrils, progressively damaging the heart, kidneys, nerves, and other organs.
1 drug guide
Mastocytosis
Mastocytosis is a rare hematological disorder characterized by clonal expansion of mast cells in bone marrow, organs, and tissues.
3 drug guides
Myelodysplastic SyndromesNot rare
Myelodysplastic syndromes are a group of blood cancers in which the bone marrow fails to produce enough healthy blood cells.
1 drug guide
Myelofibrosis
Myelofibrosis is a myeloproliferative neoplasm in which bone marrow develops scarring (fibrosis), leading to anemia, enlarged spleen, and abnormal blood cell counts.
2 drug guides
Paroxysmal Nocturnal Hemoglobinuria
Paroxysmal Nocturnal Hemoglobinuria is a rare, life-threatening blood disorder where complement-mediated destruction of red blood cells occurs due to acquired mutations in the PIGA gene.
3 drug guides
Polycythemia Vera
Polycythemia Vera is a myeloproliferative neoplasm in which bone marrow produces too many red blood cells, leading to thick blood that carries oxygen less effectively and increases clot risk.
2 drug guides
Pyruvate Kinase Deficiency
Pyruvate kinase deficiency is an inherited red blood cell disorder in which a missing or weak enzyme leaves red cells short of energy, so they break down early and cause lifelong anemia, jaundice and an enlarged spleen.
1 drug guide
Severe Combined Immunodeficiency
Severe combined immunodeficiency is a rare genetic disorder affecting both T cell and B cell immune function, resulting in severe susceptibility to all types of infections.
Sickle Cell Disease
Sickle cell disease is an inherited blood disorder where hemoglobin polymerizes under low oxygen, causing red blood cells to become rigid, sickle-shaped, and prone to hemolysis and vaso-occlusion.
5 drug guides|FDA decision Nov 1st
Systemic Mastocytosis
Systemic Mastocytosis is a rare hematologic disorder characterized by accumulation and proliferation of abnormal mast cells in bone marrow, lymphoid tissues, and other organs.
3 drug guides|FDA decision Dec 30th
Thalassemia
Thalassemia is an inherited blood disorder where reduced or absent production of one type of hemoglobin chain causes severe anemia, organ damage from iron overload, and bone abnormalities.
4 drug guides
Thrombotic Thrombocytopenic Purpura
Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening blood disorder in which small clots form in blood vessels throughout the body, using up platelets and blocking blood flow to the brain, kidneys and heart.
2 drug guides
Von Willebrand Disease
Von Willebrand disease is the most common inherited bleeding disorder, caused by quantitative or qualitative deficiency of von Willebrand factor.
Waldenström Macroglobulinemia
Waldenström Macroglobulinemia is a rare blood cancer in which malignant B-lymphocytes produce excessive amounts of a protein called macroglobulin (immunoglobulin M or IgM).
Wiskott-Aldrich Syndrome
Wiskott-Aldrich syndrome is a rare X-linked immunodeficiency characterized by thrombocytopenia, eczema, and recurrent infections.
1 drug guide
Cardiovascular rare diseases11
Arrhythmogenic Cardiomyopathy
Arrhythmogenic cardiomyopathy is a rare genetic heart disease characterized by replacement of cardiac myocardium with fibrofatty tissue, particularly affecting the right ventricle.
Barth Syndrome
Barth syndrome is an ultra-rare X-linked genetic disorder caused by mutations in the TAFAZZIN gene, which produces an enzyme essential for remodeling cardiolipin, a phospholipid that mitochondria need to generate energy.
1 drug guide
Catecholaminergic Polymorphic Ventricular Tachycardia
Catecholaminergic polymorphic ventricular tachycardia is a rare genetic arrhythmia syndrome causing life-threatening bidirectional or polymorphic ventricular tachycardia triggered by stress or emotion.
Dilated CardiomyopathyNot rare
Dilated cardiomyopathy is a condition where the heart's main pumping chamber, the left ventricle, becomes enlarged and weakened, reducing the heart's ability to pump blood efficiently.
Familial Hypertrophic CardiomyopathyNot rare
Familial hypertrophic cardiomyopathy is a genetic heart muscle disease characterized by inappropriate left ventricular hypertrophy and diastolic dysfunction.
2 drug guides
Hereditary Hemorrhagic Telangiectasia
Hereditary Hemorrhagic Telangiectasia is a rare genetic disorder characterized by abnormal blood vessel formation (telangiectasias) and arteriovenous malformations causing nosebleeds, gastrointestinal bleeding, and potentially serious internal bleeding.
Homozygous Familial Hypercholesterolemia
Homozygous Familial Hypercholesterolemia is a severe genetic disorder causing extremely high cholesterol levels from birth, leading to early heart disease and cholesterol deposits in tendons and around the eyes.
Kawasaki Disease
Kawasaki disease is an acute self-limited vasculitis of medium-sized arteries affecting primarily children under 5 years.
Moyamoya Disease
Moyamoya Disease is a rare, progressive cerebrovascular disorder characterized by abnormal narrowing of major blood vessels in the brain, combined with the development of a hazy network of fine collateral vessels.
Peripartum Cardiomyopathy
Peripartum cardiomyopathy is a rare form of heart failure that develops during the last month of pregnancy or within 5 months after delivery in women with no prior history of heart disease.
1 drug guide
Wild-Type ATTR Cardiac Amyloidosis
Wild-type ATTR cardiac amyloidosis is an age-related disease where normal transthyretin protein spontaneously misfolds and accumulates in the heart, causing progressive heart failure.
4 drug guides
Connective Tissue & Musculoskeletal rare diseases8
Achondroplasia
Achondroplasia is the most common form of short-limbed dwarfism, caused by a mutation in the FGFR3 gene that disrupts the conversion of cartilage to bone in the growth plates.
1 drug guide|FDA decision Feb 4th, 2027
Ehlers-Danlos Syndrome
Ehlers-Danlos syndrome is a group of genetic connective tissue disorders characterized by abnormal collagen synthesis or structure, causing hyperextensible skin, joint hypermobility, tissue fragility, and varying systemic complications.
Fibrodysplasia Ossificans Progressiva
Fibrodysplasia Ossificans Progressiva (FOP) is an extremely rare genetic disorder characterized by progressive heterotopic ossification, where soft tissues (muscles, tendons, ligaments) gradually transform into bone.
3 drug guides
Hajdu-Cheney Syndrome
Hajdu-Cheney syndrome is a rare genetic skeletal dysplasia characterized by acroosteolysis (loss of terminal phalanges and digits), progressive joint disease, and distinctive craniofacial features.
Marfan Syndrome
Marfan syndrome is an autosomal dominant genetic disorder affecting connective tissue throughout the body, caused by mutations in the FBN1 gene encoding fibrillin-1.
Osteogenesis Imperfecta
Osteogenesis imperfecta is a genetic disorder affecting type I collagen synthesis or structure, causing bones to break easily with little or no apparent trauma.
Stickler Syndrome
Stickler syndrome is a rare inherited connective tissue disorder caused by mutations affecting type II collagen or related proteins.
Vascular Ehlers-Danlos Syndrome
Vascular EDS is a rare genetic disorder affecting connective tissue that causes fragility in arteries and internal organs, making people vulnerable to life-threatening ruptures and bleeding.
1 drug guide
Dermatologic rare diseases7
Bullous Pemphigoid
Bullous pemphigoid is an autoimmune blistering disorder caused by autoantibodies against basement membrane proteins, particularly BP180 and BP230.
Epidermolysis Bullosa
Epidermolysis bullosa is a group of rare genetic blistering disorders caused by mutations affecting proteins anchoring the epidermis to the dermis.
3 drug guides
Generalized Pustular Psoriasis
Generalized pustular psoriasis (GPP) is the rarest form of psoriasis and behaves like a different disease.
1 drug guide
Linear IgA Disease
Linear IgA disease is a rare autoimmune blistering disorder characterized by linear IgA deposits along the basement membrane zone.
Morphea
Morphea is a localized form of scleroderma characterized by hardened patches of skin with hyperpigmentation or hypopigmentation.
Pemphigus Vulgaris
Pemphigus Vulgaris is a rare, potentially life-threatening autoimmune blistering disorder where the body produces antibodies against cell-to-cell adhesion molecules, causing blisters and erosions in the skin and mucous membranes.
1 drug guide
Porphyria Cutanea Tarda
Porphyria cutanea tarda is the most common porphyria, characterized by deficiency in uroporphyrinogen decarboxylase leading to accumulation of porphyrin precursors.
Endocrine & Hormonal rare diseases12
Acromegaly
Acromegaly is a rare hormonal disorder caused by excessive growth hormone production, typically from a pituitary adenoma, resulting in abnormal growth of hands, feet, and facial features.
7 drug guides|FDA decision Dec 18th
Addison Disease
Addison Disease is a rare endocrine disorder in which the adrenal glands fail to produce adequate cortisol and aldosterone due to autoimmune destruction, infection, or other causes.
Central Diabetes Insipidus
Central diabetes insipidus results from deficiency of antidiuretic hormone (vasopressin) due to pituitary or hypothalamic dysfunction.
Congenital Adrenal Hyperplasia
Congenital adrenal hyperplasia comprises rare autosomal recessive disorders of cortisol synthesis.
1 drug guide
Cushing Disease
Cushing Disease is a rare endocrine disorder caused by an ACTH-secreting pituitary adenoma that leads to excessive cortisol production.
4 drug guides
Familial Medullary Thyroid Carcinoma
Familial medullary thyroid carcinoma is an autosomal dominant cancer predisposition syndrome caused by germline RET mutations.
Graves’ DiseaseNot rare
Graves' disease is the most common cause of hyperthyroidism, an autoimmune condition where antibodies stimulate the thyroid gland to produce excessive thyroid hormone.
1 drug guide
Hypoparathyroidism
Hypoparathyroidism is an endocrine disorder caused by insufficient production of parathyroid hormone (PTH), resulting in chronically low calcium and elevated phosphorus levels in the blood.
1 drug guide
MCT8 Deficiency
MCT8 deficiency, also called Allan-Herndon-Dudley syndrome, is a rare X-linked disorder in which thyroid hormone cannot enter the brain because the transporter that carries it, MCT8, is missing or broken.
1 drug guide
Multiple Endocrine Neoplasia Type 1
Multiple endocrine neoplasia type 1 is an autosomal dominant syndrome characterized by tumors of the parathyroid, pancreatic islet cells, and anterior pituitary.
Pheochromocytoma
Pheochromocytoma is a rare neuroendocrine tumor arising from chromaffin cells of the adrenal medulla that produces excessive catecholamines (epinephrine and norepinephrine).
1 drug guide
X-Linked Hypophosphatemia
X-Linked Hypophosphatemia is a rare genetic bone disorder where the body cannot properly regulate phosphate levels, leading to rickets, bone pain, and skeletal deformities.
Eye & Vision rare diseases5
Geographic AtrophyNot rare
Geographic atrophy is the advanced form of dry age-related macular degeneration, characterized by progressive loss of retinal pigment epithelium, photoreceptors, and choriocapillaris in well-defined areas of the macula.
1 drug guide
Leber Congenital Amaurosis
Leber congenital amaurosis is a group of rare inherited retinal dystrophies that cause severe vision loss or blindness from birth or early infancy.
1 drug guide
Retinitis Pigmentosa
Retinitis pigmentosa is a group of inherited retinal dystrophies causing progressive degeneration of the photoreceptor layer of the eye.
1 drug guide
Stargardt Disease
Stargardt disease is the most common inherited macular dystrophy, caused primarily by mutations in the ABCA4 gene that lead to toxic accumulation of lipofuscin (a waste byproduct of the visual cycle) in retinal pigment epithelial cells.
FDA decision Feb 12th, 2027
Thyroid Eye Disease
Thyroid eye disease (TED) is a rare autoimmune condition in which the immune system attacks the muscles and fat behind the eyes, causing bulging eyes, double vision, pain, and in severe cases vision loss.
2 drug guides|FDA decision Oct 15th
Gastrointestinal rare diseases7
Autoimmune Hepatitis
Autoimmune Hepatitis (AIH) is a chronic liver disease characterized by persistent inflammation and progressive fibrosis of the liver due to loss of immune tolerance to hepatocyte antigens.
Eosinophilic Esophagitis
Eosinophilic Esophagitis is a rare allergic/immune-mediated inflammatory disease of the esophagus characterized by eosinophil infiltration causing progressive narrowing and dysfunction.
GastroparesisNot rare
Gastroparesis is a condition in which the stomach empties food too slowly even though nothing is blocking it, causing early fullness, nausea, vomiting, bloating and upper belly pain.
4 drug guides
Hereditary Diffuse Gastric Cancer
Hereditary diffuse gastric cancer is an autosomal dominant cancer predisposition syndrome caused by germline CDH1 mutations.
Primary Biliary Cholangitis
Primary Biliary Cholangitis (PBC) is a chronic autoimmune liver disease in which the immune system mistakenly attacks the small bile ducts in the liver, leading to bile duct destruction and progressive liver damage.
3 drug guides|FDA decision Nov 27th
Primary Sclerosing Cholangitis
Primary Sclerosing Cholangitis (PSC) is a rare chronic liver disease characterized by inflammation and progressive scarring of the bile ducts, both inside and outside the liver.
Short Bowel Syndrome
Short Bowel Syndrome is a rare condition resulting from surgical removal or congenital absence of a significant portion of the small intestine, leading to malabsorption, diarrhea, and nutritional deficiencies.
Kidney & Renal rare diseases10
Alport Syndrome
Alport Syndrome is a genetic disorder that causes progressive damage to the kidneys, ears, and eyes due to defects in a type of collagen that provides structure and flexibility to tissues.
Atypical Hemolytic Uremic Syndrome
Atypical Hemolytic Uremic Syndrome (aHUS) is a rare kidney disease caused by uncontrolled activation of the complement system, a part of the immune system that normally helps fight infection.
C3 Glomerulopathy
C3 glomerulopathy is a group of rare kidney diseases caused by dysregulation of the alternative complement pathway, leading to uncontrolled C3 deposition in the glomeruli.
2 drug guides
Focal Segmental Glomerulosclerosis
Focal Segmental Glomerulosclerosis (FSGS) is a kidney disease characterized by scarring of some glomeruli, the tiny filtering units that remove waste from the blood.
1 drug guide
IgA Nephropathy
IgA nephropathy is the most common primary glomerulonephritis worldwide, caused by abnormal IgA1 antibodies depositing in the kidney's mesangium, activating complement pathways and triggering inflammation that progressively damages the kidneys.
12 drug guides|FDA decision Nov 30th
IgA Vasculitis with Nephritis
IgA vasculitis is a small-vessel vasculitis characterized by IgA immune complex deposition in kidneys and other organs.
Lupus Nephritis
Lupus nephritis is kidney inflammation caused by systemic lupus erythematosus (SLE), in which the immune system attacks the kidneys' filters and, without treatment, can lead to kidney failure.
3 drug guides
Membranous Nephropathy
Membranous nephropathy is a rare autoimmune kidney disease where the body's own antibodies attack proteins in the kidney's filtering units (glomeruli).
1 drug guide|FDA decision by November 2026
Polycystic Kidney DiseaseNot rare
Polycystic Kidney Disease is a genetic disorder characterized by the growth of thousands of cysts in the kidneys, gradually replacing normal kidney tissue and leading to kidney failure.
Primary Hyperoxaluria
Primary hyperoxaluria is a rare inherited metabolic disorder in which the liver overproduces oxalate, a substance that combines with calcium to form kidney stones and can eventually cause kidney failure.
1 drug guide
Liver & Hepatic rare diseases2
Alagille Syndrome
Alagille syndrome is a rare autosomal dominant disorder affecting the liver, heart, skeleton, face, and eyes.
Progressive Familial Intrahepatic Cholestasis
Progressive familial intrahepatic cholestasis comprises a group of rare inherited disorders causing progressive cholestasis and liver disease in childhood.
Metabolic & Lysosomal rare diseases30
Aceruloplasminemia
Aceruloplasminemia is a rare inherited disorder of iron metabolism caused by mutations in the CP gene encoding ceruloplasmin.
2 drug guides
ATTR Amyloidosis (Transthyretin Amyloidosis)
ATTR amyloidosis is a rare progressive disease where abnormal transthyretin protein accumulates as amyloid deposits in the heart, nerves, and other organs.
6 drug guides
Cerebrotendinous Xanthomatosis
Cerebrotendinous xanthomatosis (CTX) is a rare inherited metabolic disorder caused by mutations in the CYP27A1 gene, which produces an enzyme essential for converting cholesterol into bile acids.
1 drug guide
Cystinosis
Cystinosis is an inherited condition in which the amino acid cystine builds up inside cells and forms crystals that damage organs, especially the kidneys and eyes.
4 drug guides
Fabry Disease
Fabry disease is a rare inherited lysosomal storage disorder where a missing enzyme causes fatty substances called globotriaosylceramide to accumulate in cells throughout the body.
3 drug guides
Familial Chylomicronemia Syndrome
Familial Chylomicronemia Syndrome is a rare inherited metabolic disorder where the body cannot break down certain fats (triglycerides) normally, causing dangerously high blood fat levels.
2 drug guides
Galactosemia
Galactosemia is a rare autosomal recessive disorder of galactose metabolism caused by galactose-1-phosphate uridyltransferase (GALT) deficiency.
Gaucher Disease
Gaucher disease is a rare inherited lysosomal storage disorder caused by deficiency of the enzyme glucocerebrosidase, resulting in accumulation of fatty substances in the spleen, liver, and bone marrow.
6 drug guides|FDA decision Nov 25th
Glycogen Storage Disease Type Ia
Glycogen storage disease type Ia (GSD Ia, von Gierke disease) is an inherited condition in which the liver cannot release sugar into the blood between meals, so blood sugar drops dangerously low without frequent feeding and glycogen and fat build up in the liver and kidneys.
1 drug guide
Homocystinuria
Homocystinuria is a rare inherited metabolic disorder characterized by elevated homocysteine levels in blood and urine. 3 biochemically distinct types exist; the most common involves cystathionine beta-synthase deficiency.
Hunter Syndrome
Hunter syndrome is an X-linked lysosomal storage disorder caused by deficiency of iduronate-2-sulfatase enzyme, leading to accumulation of glycosaminoglycans in cells and tissues.
2 drug guides
Krabbe Disease
Krabbe Disease is a rare lysosomal storage disorder caused by deficiency of the enzyme galactocerebrosidase (GALC), which breaks down galactocerebroside, a major component of myelin.
Leigh Syndrome
Leigh syndrome is a rare inherited disorder in which the mitochondria, the parts of cells that make energy, cannot supply enough energy to the brain.
Maple Syrup Urine Disease
Maple syrup urine disease is a rare inherited metabolic disorder where the body cannot properly break down branched-chain amino acids (leucine, isoleucine, and valine).
Maple Syrup Urine Disease Type II
Maple syrup urine disease type II is an intermediate-severity form of a rare organic acidemia caused by branched-chain alpha-ketoacid dehydrogenase complex deficiency.
Menkes Disease
Menkes disease is a rare X-linked recessive disorder caused by mutations in the ATP7A gene, which encodes a copper-transporting ATPase essential for distributing copper to copper-dependent enzymes throughout the body.
1 drug guide
Metachromatic Leukodystrophy
Metachromatic Leukodystrophy (MLD) is a lysosomal storage disorder resulting from deficiency of the enzyme arylsulfatase A (ARSA), which breaks down sulfatides, critical components of myelin.
1 drug guide
Methylmalonic Acidemia
Methylmalonic acidemia is a group of inherited metabolic disorders in which the body cannot properly break down certain proteins and fats, leading to toxic buildup of methylmalonic acid.
Mucopolysaccharidosis Type I
Mucopolysaccharidosis Type I (MPS I) is a lysosomal storage disorder caused by deficiency of the enzyme alpha-L-iduronidase, which breaks down glycosaminoglycans (GAGs).
Mucopolysaccharidosis Type IVA
Mucopolysaccharidosis Type IVA (Morquio A syndrome) is a lysosomal storage disorder caused by deficiency of the enzyme N-acetylgalactosamine-6-sulfatase (GALNS).
Mucopolysaccharidosis Type VI
Mucopolysaccharidosis Type VI (Maroteaux-Lamy syndrome) is a lysosomal storage disorder caused by deficiency of the enzyme arylsulfatase B, leading to accumulation of dermatan sulfate and chondroitin 4-sulfate in tissues.
Niemann-Pick Disease
Niemann-Pick disease is a rare lysosomal storage disorder where the body cannot properly break down cholesterol and other lipids within cells.
1 drug guide
Phenylketonuria
Phenylketonuria is an inherited metabolic disorder caused by a missing enzyme that prevents the body from properly breaking down the amino acid phenylalanine.
1 drug guide
Pompe Disease
Pompe disease is a rare inherited lysosomal storage disorder caused by deficiency of the enzyme acid alpha-glucosidase, leading to excessive accumulation of glycogen in muscles and organs.
3 drug guides
Pyruvate Dehydrogenase Complex Deficiency
Pyruvate dehydrogenase complex deficiency (PDCD) is a rare inherited mitochondrial disorder in which cells cannot fully turn carbohydrates into energy, causing lactic acid buildup and damage that mostly affects the developing brain.
Sanfilippo Syndrome
Sanfilippo syndrome, formally mucopolysaccharidosis type III (MPS III), is a lysosomal storage disorder in which the body cannot break down a sugar chain called heparan sulfate.
1 drug guide
Tay-Sachs Disease
Tay-Sachs disease is a rare autosomal recessive lysosomal storage disorder caused by deficiency of the enzyme hexosaminidase A, leading to accumulation of GM2 gangliosides in nerve cells.
Tyrosinemia Type I
Tyrosinemia type I is a rare autosomal recessive disorder of tyrosine metabolism caused by fumarylacetoacetate hydrolase (FAH) deficiency.
Urea Cycle Disorders
Urea Cycle Disorders (UCDs) are a group of genetic conditions affecting the enzymes that convert toxic ammonia to urea for excretion.
Wilson Disease
Wilson disease is a rare inherited disorder of copper metabolism caused by mutations in the ATP7B gene.
7 drug guides
Neurological & Neuromuscular rare diseases46
Alexander Disease
Alexander disease is a rare inherited leukodystrophy caused by mutations in the GFAP gene affecting astrocyte function.
1 drug guide
Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis is a progressive neurodegenerative disease destroying motor neurons in the brain and spinal cord.
5 drug guides
Angelman Syndrome
Angelman Syndrome is a rare neurological disorder caused by loss of function of the UBE3A gene on the maternal chromosome 15.
Aromatic L-Amino Acid Decarboxylase Deficiency
AADC deficiency is a rare inherited neurological disorder that affects the brain's ability to produce dopamine and serotonin, leading to severe developmental delays, movement problems, and involuntary eye movements.
1 drug guide
Ataxia-Telangiectasia
Ataxia-telangiectasia (A-T) is a rare inherited disorder in which the ATM gene, which coordinates DNA repair, does not work.
1 drug guide
Batten Disease
Batten disease is a rare inherited neurological disorder caused by mutations in genes affecting lysosomal function, leading to accumulation of lipofuscin (age pigment) in neurons.
Becker Muscular Dystrophy
Becker Muscular Dystrophy (BMD) is an X-linked inherited muscular dystrophy caused by mutations in the dystrophin gene that produce a partially functional dystrophin protein.
Canavan Disease
Canavan disease is a rare autosomal recessive leukodystrophy caused by mutations in the ASPA gene affecting aspartoacylase enzyme.
CDKL5 Deficiency Disorder
CDKL5 deficiency disorder is a severe genetic condition that causes early-onset seizures, usually beginning within the first few months of life, along with significant developmental delays and movement problems.
1 drug guide
Cerebral Adrenoleukodystrophy
Cerebral adrenoleukodystrophy is the most severe form of X-linked adrenoleukodystrophy, caused by mutations in the ABCD1 gene that impair breakdown of very-long-chain fatty acids.
1 drug guide
Charcot-Marie-Tooth Disease
Charcot-Marie-Tooth disease (CMT) is the most common inherited disease of the peripheral nervous system.
5 drug guides
Chronic Inflammatory Demyelinating Polyneuropathy
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is an autoimmune disorder affecting the peripheral nerves, causing progressive weakness and impaired function in the legs and arms.
Corticobasal Degeneration
Corticobasal degeneration is a rare neurodegenerative disorder characterized by asymmetric cortical and basal ganglia pathology with progressive motor and cognitive decline.
Dravet Syndrome
Dravet Syndrome is a severe form of epilepsy that typically begins in infancy with prolonged seizures triggered by fever.
7 drug guides
Duchenne Muscular Dystrophy
Duchenne muscular dystrophy is an X-linked genetic disorder causing progressive muscle weakness and degeneration, beginning in early childhood.
9 drug guides|FDA decision Nov 22nd
Facioscapulohumeral Muscular Dystrophy
Facioscapulohumeral Muscular Dystrophy (FSHD) is an inherited muscular dystrophy characterized by progressive weakness of the facial, shoulder, and upper arm muscles.
Focal EpilepsyNot rare
Focal epilepsy is a neurological disorder characterized by recurrent seizures that originate in a specific area of the brain.
8 drug guides
Fragile X Syndrome
Fragile X Syndrome is the most common inherited cause of intellectual disability and autism spectrum disorder.
Friedreich Ataxia
Friedreich ataxia is an autosomal recessive neurodegenerative disease causing progressive damage to the nervous system, resulting in loss of coordination (ataxia), weakness, and heart problems.
Guillain-Barré Syndrome
Guillain-Barré syndrome is a rare autoimmune neurological disorder in which the body's immune system attacks the peripheral nerves, causing rapidly progressive muscle weakness that typically starts in the legs and can spread to the upper body and face.
Hereditary Spastic Paraplegia
Hereditary Spastic Paraplegia (HSP) refers to a group of genetic neurological disorders characterized by progressive weakness and spasticity of the leg muscles, leading to progressive difficulty walking.
Hereditary Spastic Paraplegia Type 4
Spastic paraplegia type 4 is a rare inherited neurological disorder causing progressive stiffness and weakness of the lower limbs.
Huntington Disease
Huntington disease is an autosomal dominant neurodegenerative disorder caused by an expanded CAG trinucleotide repeat in the huntingtin gene.
3 drug guides
Inherited Erythromelalgia
Inherited erythromelalgia is a rare autosomal dominant pain disorder caused by gain-of-function mutations in the SCN9A gene, which encodes the Nav1.7 voltage-gated sodium channel.
KCNT1-Related Epilepsy
KCNT1-related epilepsy is a group of rare genetic epilepsies caused by changes in the KCNT1 gene, which makes a potassium channel that helps control how easily brain cells fire.
Lambert-Eaton Myasthenic Syndrome
Lambert-Eaton Myasthenic Syndrome (LEMS) is a rare neuromuscular disorder caused by autoimmune attack on the synaptic terminals where nerves connect to muscles.
Lennox-Gastaut Syndrome
Lennox-Gastaut Syndrome is a severe childhood epilepsy characterized by multiple types of seizures that are often resistant to medication, intellectual disability, and characteristic EEG findings showing slow spike-wave patterns.
Limb-Girdle Muscular Dystrophy
Limb-Girdle Muscular Dystrophy (LGMD) refers to a genetically heterogeneous group of muscular dystrophies characterized by progressive weakness of the hip and shoulder girdle muscles.
MOG Antibody-Associated Disease
MOG antibody-associated disease (MOGAD) is a rare autoimmune condition in which antibodies attack a protein on the myelin coating of nerves in the optic nerves, spinal cord and brain, causing attacks of vision loss, weakness, numbness and, in children, brain inflammation.
Multiple System Atrophy
Multiple system atrophy is a rare, progressive neurodegenerative disorder characterized by dysfunction of the autonomic nervous system and movement disorders.
Myasthenia Gravis
Myasthenia gravis is a chronic autoimmune neuromuscular disorder causing muscle weakness and rapid fatigue.
8 drug guides|FDA decision in November 2026
Myotonic Dystrophy
Myotonic Dystrophy (MD) is the most common muscular dystrophy in adults, characterized by progressive muscle weakness and myotonia—the inability of muscles to relax after contraction.
2 drug guides
Narcolepsy Type 1
Narcolepsy type 1 is a chronic neurologic disorder caused by loss of hypocretin-producing neurons, resulting in severe daytime somnolence and cataplexy.
1 drug guide|FDA decision May 1st, 2027
Neurofibromatosis Type 1
Neurofibromatosis type 1 is a genetic disorder caused by mutations in the NF1 gene on chromosome 17, which encodes neurofibromin, a tumor suppressor protein.
2 drug guides
Niemann-Pick Disease Type C
Niemann-Pick Disease Type C (NPC) is a rare, progressive lysosomal lipid storage disorder caused by mutations in the NPC1 or NPC2 genes, which encode proteins critical for cholesterol and lipid trafficking.
3 drug guides|FDA decision Nov 17th
Phelan-McDermid Syndrome
Phelan-McDermid Syndrome results from deletions or mutations of the SHANK3 gene on chromosome 22q13, leading to intellectual disability, autism spectrum disorder features, and developmental delay.
Prader-Willi Syndrome
Prader-Willi Syndrome is a rare genetic disorder affecting chromosome 15 that results in weak muscle tone, low hormone levels, incomplete sexual development, intellectual disability, and a constant feeling of hunger leading to obesity.
1 drug guide
Progressive Supranuclear Palsy
Progressive supranuclear palsy is a rare atypical Parkinsonian disorder characterized by progressive vertical supranuclear gaze palsy, postural instability, and cognitive decline.
Rett Syndrome
Rett syndrome is a rare genetic neurological disorder affecting brain development, almost exclusively in girls.
4 drug guides
SCN2A Encephalopathy
SCN2A encephalopathy is a rare genetic epilepsy caused by a change in the SCN2A gene, which builds a sodium channel that brain cells use to fire.
2 drug guides
SCN8A Encephalopathy
SCN8A encephalopathy is a rare genetic epilepsy caused by a change in the SCN8A gene, which builds the Nav1.6 sodium channel that brain cells use to fire.
1 drug guide
Spinal Muscular Atrophy
Spinal muscular atrophy is an autosomal recessive genetic disorder affecting motor neurons in the spinal cord, causing progressive muscle weakness and atrophy.
6 drug guides
Spinocerebellar Ataxia
Spinocerebellar ataxias are a group of inherited neurodegenerative disorders caused by mutations in various genes, leading to progressive degeneration of the cerebellum and its connections.
1 drug guide
Stiff Person Syndrome
Stiff Person Syndrome (SPS) is a rare neurological disorder characterized by progressive stiffness and rigidity of the trunk and limbs, along with painful muscle spasms.
Thymidine Kinase 2 Deficiency
Thymidine Kinase 2 Deficiency (TK2d) is an ultra-rare inherited mitochondrial disease caused by mutations in the TK2 gene, which produces an enzyme essential for making and maintaining mitochondrial DNA in muscle cells.
1 drug guide
Usher Syndrome
Usher syndrome is an inherited condition combining hearing loss and progressive vision loss, eventually leading to deaf-blindness.
Pulmonary & Respiratory rare diseases9
Alpha-1 Antitrypsin Deficiency
Alpha-1 antitrypsin deficiency is a genetic disorder affecting the lungs and liver, caused by insufficient production of the protective protein alpha-1 antitrypsin.
5 drug guides
Cystic Fibrosis
Cystic fibrosis is an autosomal recessive genetic disorder affecting the CFTR protein, which normally regulates chloride transport.
5 drug guides
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis is an inflammatory lung disease caused by repeated inhalation of antigens triggering immune-mediated lung inflammation.
Idiopathic Pulmonary Fibrosis
Idiopathic pulmonary fibrosis is a chronic, progressive lung disease characterized by scarring (fibrosis) of lung tissue.
4 drug guides|FDA decision in late April 2027
Lymphangioleiomyomatosis
Lymphangioleiomyomatosis (LAM) is a rare progressive lung disease characterized by proliferation of abnormal smooth muscle-like cells (LAM cells) in the lungs, lymph nodes, and kidneys.
Pulmonary Alveolar Proteinosis
Pulmonary alveolar proteinosis (PAP) is a rare lung disease in which a soapy substance called surfactant builds up inside the air sacs because the cells meant to clear it have stopped working.
1 drug guide
Pulmonary Arterial Hypertension
Pulmonary arterial hypertension is a rare disease characterized by abnormally high blood pressure in the pulmonary arteries, causing progressive heart and lung damage.
12 drug guides|FDA decision Jun 24th, 2027
Pulmonary Langerhans Cell Histiocytosis
Pulmonary Langerhans Cell Histiocytosis (PLCH) is a rare inflammatory lung disease characterized by accumulation and proliferation of abnormal Langerhans cells in the lungs.
Recurrent Respiratory Papillomatosis
Recurrent respiratory papillomatosis (RRP) is a rare disease in which wart-like growths caused by HPV types 6 and 11 grow in the airway, most often on the voice box.
2 drug guides
Rare Cancers rare diseases15
Adrenocortical Carcinoma
Adrenocortical carcinoma is a rare, aggressive cancer of the adrenal cortex, the outer layer of the adrenal glands that sit on top of each kidney.
3 drug guides
Cholangiocarcinoma
Cholangiocarcinoma is a rare and aggressive cancer that forms in the bile ducts, the thin tubes that carry digestive fluid (bile) from the liver to the small intestine.
7 drug guides
Desmoplastic Small Round Cell Tumor
Desmoplastic small round cell tumor is a rare aggressive sarcoma characterized by EWSR1-WT1 fusion and dense desmoplasia.
Diffuse Intrinsic Pontine Glioma
Diffuse intrinsic pontine glioma (DIPG) is an aggressive childhood brain tumor that grows in the pons, the part of the brainstem controlling breathing, swallowing, and movement.
1 drug guide
Gastrointestinal Stromal Tumor
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, arising from the interstitial cells of Cajal or their precursors.
2 drug guides|FDA decision Nov 30th
Hodgkin Lymphoma
Hodgkin lymphoma is a cancer of the lymphatic system characterized by the presence of abnormal Reed-Sternberg cells.
Medullary Thyroid Cancer
Medullary thyroid cancer (MTC) is a rare neuroendocrine tumor arising from the parafollicular C cells of the thyroid gland, accounting for 2-4% of all thyroid cancers.
Merkel Cell Carcinoma
Merkel cell carcinoma is a rare, aggressive skin cancer that arises from Merkel cells, specialized touch receptors in the skin.
1 drug guide
Mesothelioma
Mesothelioma is a rare, aggressive cancer that develops in the mesothelium, the thin layer of tissue covering most internal organs.
Multiple Myeloma
Multiple myeloma is a cancer of plasma cells, the white blood cells that make antibodies.
2 drug guides
Neuroendocrine TumorsNot rare
Neuroendocrine tumors (NETs) grow from hormone-making cells, most often in the small intestine, pancreas, rectum or lungs.
3 drug guides
NTRK Fusion Cancer
NTRK fusion cancers are a group of rare tumors driven by gene fusions involving 1 of 3 NTRK genes (NTRK1, NTRK2, or NTRK3).
7 drug guides
Paraganglioma
Paragangliomas are rare neuroendocrine tumors arising from chromaffin tissue outside the adrenal medulla.
1 drug guide
Primary Central Nervous System Lymphoma
Primary central nervous system lymphoma (PCNSL) is a fast-growing lymphoma that starts in the brain, spinal cord, eyes or the membranes around them and usually stays there.
1 drug guide
RET Fusion Cancer
RET fusion cancers are a group of rare tumors driven by chromosomal rearrangements that fuse the RET gene with a partner gene, creating an abnormal protein that drives uncontrolled cell growth.
Tick-Borne & Infectious rare diseases14
Alpha-Gal SyndromeNot rare
Alpha-Gal Syndrome (AGS) is a tick-bite-triggered IgE allergy to galactose-α-1,3-galactose, a sugar molecule found in non-primate mammals.
Anaplasmosis
Anaplasmosis is a rare tick-borne disease caused by the bacterium Anaplasma phagocytophilum, which infects white blood cells.
1 drug guide
Babesiosis
Babesiosis is a rare tick-borne disease caused by Babesia parasites that infect and destroy red blood cells.
5 drug guides
Bartonella Infection
Bartonella infections are caused by a group of bacteria that live inside cells and can affect the blood vessels, lymph nodes, liver, spleen, heart valves and nervous system.
3 drug guides
Borrelia Miyamotoi Disease
Borrelia miyamotoi disease is a recently recognized infection spread by the same blacklegged ticks that carry Lyme disease.
1 drug guide
Bourbon Virus Disease
Bourbon virus is a very rare tick-borne virus discovered in Bourbon County, Kansas, in 2014, believed to be spread by the lone star tick.
Colorado Tick Fever
Colorado tick fever is a rare viral infection spread by the Rocky Mountain wood tick at elevations of 4,000 to 10,000 feet in the western United States and Canada.
Ehrlichiosis
Ehrlichiosis is a rare tick-borne bacterial infection, spread mainly by the lone star tick, that causes sudden fever, headache, muscle aches and low blood counts.
1 drug guide
Heartland Virus Disease
Heartland virus is a rare tick-borne virus, first identified in Missouri in 2009, that is spread mainly by the lone star tick.
Powassan Virus Disease
Powassan virus is a rare tick-borne virus, related to tick-borne encephalitis virus, that can infect the brain and its lining.
Rocky Mountain Spotted Fever
Rocky Mountain spotted fever is a rare but dangerous tick-borne infection that starts with fever and headache and can become fatal within days without doxycycline.
1 drug guide
Tick-Borne Encephalitis
Tick-borne encephalitis is a viral infection of the brain spread by ticks across parts of Europe and northern Asia.
1 drug guide
Tick-Borne Relapsing Fever
Tick-borne relapsing fever is a rare bacterial infection, spread by soft ticks that live in rodent nests, that causes fevers lasting about 3 days, then a week without fever, then fever again.
1 drug guide
Tularemia
Tularemia is a rare bacterial infection spread by ticks, deer flies, and contact with infected animals such as rabbits and rodents.
1 drug guide
Other rare diseases8
22q11.2 Deletion Syndrome
22q11.2 deletion syndrome results from a microdeletion on chromosome 22, causing a spectrum of phenotypes including cardiac defects, cleft palate, thymic hypoplasia, hypocalcemia, and intellectual disability.
Cri du Chat Syndrome
Cri du chat syndrome results from a partial deletion of the short arm of chromosome 5, characterized by distinctive high-pitched cry in infants, intellectual disability, and facial dysmorphism.
Noonan Syndrome
Noonan syndrome is a common autosomal dominant disorder caused by RAS/MAPK pathway mutations, characterized by distinctive facial features, short stature, cardiac abnormalities, and developmental delays.
Progeria
Progeria is an extremely rare genetic disorder causing rapid aging in children.
Sarcoidosis
Sarcoidosis is an inflammatory disease characterized by formation of granulomas (clusters of immune cells) in multiple organs, most commonly the lungs and lymph nodes.
Tuberous Sclerosis
Tuberous sclerosis is an autosomal dominant genetic disorder caused by mutations in TSC1 or TSC2 genes, resulting in dysregulated mTOR signaling and widespread benign tumor growth.
Turner Syndrome
Turner syndrome results from complete or partial absence of an X chromosome in females, causing short stature, gonadal dysgenesis, cardiac and renal abnormalities.
Williams Syndrome
Williams syndrome is a rare genetic condition caused by a 7q11.23 deletion including the elastin gene, characterized by distinctive features, supravalvular aortic stenosis, hypercalcemia, and characteristic behavioral phenotype with strong social drive.
Rare disease directory questions
What counts as a rare disease?
In the United States, the Orphan Drug Act defines a rare disease as one that affects fewer than 200,000 people. The FDA estimates there are more than 10,000 rare diseases, together affecting more than 30 million Americans, about half of them children.
How many rare diseases does Trial Friend cover?
229 conditions so far, grouped into 16 body systems. Each has its own page with symptoms, who it affects, approved treatments, drugs in clinical trials and the trials recruiting now, filtered to trials that list that condition.
Why are some conditions marked not rare?
A few conditions in the directory, such as multiple sclerosis and Graves' disease, affect more than 200,000 Americans. They are included because they have individually rare forms, rare complications or the same research and access problems as rare diseases, and each page explains why. They are marked Not rare so the label stays accurate.
Rare disease definition from the U.S. Food and Drug Administration. Each condition page lists its own sources.