Browse plain-English disease and condition guides, including symptoms, causes, diagnosis, treatment options, prevention, and when to seek medical care.
Anal Anomalies–Porokeratosis Syndrome, often referred to as AAPS, is a rare medical condition that affects various aspects of a person’s health. In this comprehensive article, we...
Read article11β-HSD2 deficiency is a rare genetic condition in which the body cannot properly switch the hormone cortisol into its inactive form, cortisone, inside certain kidney cells....
Read article1p36 microdeletion syndrome (also called 1p36 deletion syndrome) is a genetic condition that starts before birth. A small piece of chromosome 1, from the short arm...
Read article1q21.1 deletion syndrome (also called 1q21.1 microdeletion) is a genetic disorder caused by the loss of a small segment of DNA on the long arm (q...
Read article1q21.1 duplication syndrome (also called 1q21.1 microduplication) is a chromosomal copy-number variant in which a small segment of genetic material on the long (q) arm of...
Read article1q21.1 recurrent microdeletion is a tiny missing piece of DNA on chromosome 1, at a place called “1q21.1.” In this condition, one copy of chromosome 1...
Read article2-methylacyl-CoA racemase deficiency is a very rare inherited metabolic disease. It happens when the body does not make enough working AMACR enzyme. This enzyme helps break...
Read article2,8-dihydroxyadenine (DHA) urolithiasis is a rare form of kidney stone disease. It happens when the body cannot recycle the purine base adenine in the normal “salvage”...
Read article2,8-dihydroxyadeninuria is a rare, inherited problem of purine recycling. Your body normally reuses adenine (a building block of DNA) using an enzyme called APRT (adenine phosphoribosyltransferase)....
Read article21-hydroxylase-deficient congenital adrenal hyperplasia (CAH) is a genetic disease that affects how the adrenal glands make important hormones called cortisol and aldosterone. The adrenal glands are...
Read article3-beta-hydroxy-delta-5-c27-steroid dehydrogenase deficiency is a very rare inherited liver disease. It is one of the bile acid synthesis disorders. In this condition, the liver cannot make...
Read article3-methylglutaconic aciduria type 2 is a rare, inherited condition that almost always affects boys. It is also called Barth syndrome. It happens because of a change...
Read articleAcquired neuromyotonia is an inflammatory disorder characterized by abnormal nerve impulses from the peripheral nerves that result in continuous muscle fiber activity spontaneous and continuous muscle...
Read articleLipodystrophy syndromes are a group of genetic or acquired disorders in which the body is unable to produce and maintain healthy fat tissue. The medical condition is...
Read articleLipodystrophies are conditions that share the common finding of a reduction in subcutaneous fat. There are multiple subtypes of lipodystrophy, which may be either congenital or...
Read articleAcquired lipodystrophy is a general term for types of lipodystrophy that are not inherited, but rather acquired at some point during life. Acquired lipodystrophies do not...
Read articleAcquired hemophilia (AH) is a rare autoimmune disorder characterized by bleeding that occurs in patients with no personal or family history of diseases related to clotting/coagulation....
Read articleAcquired aplastic anemia is a rare, serious blood disorder, due to the failure of the bone marrow fails to produce blood cells. Bone marrow is the...
Read articleAn acoustic neuroma is a type of non-cancerous (benign) brain tumor. It’s also known as a vestibular schwannoma. A benign brain tumor is a growth in the...
Read articleThe methylmalonic acidemias are organic acidemias caused by an enzymatic defect in the metabolism of four amino acids (methionine, threonine, isoleucine, and valine). This results in...
Read articleAcid sphingomyelinase deficiency (ASMD) is a rare progressive genetic disorder that results from a deficiency of the enzyme acid sphingomyelinase, which is required to break down...
Read articleAchondroplasia is the most commonly occurring abnormality of bone growth (skeletal dysplasia), occurring in approximately 1 in 20,000-30,000 live births. This genetic disorder is caused by...
Read articleAchondrogenesis is a group of severe disorders that affect the cartilage and bone development. These conditions are characterized by a small body, short limbs, and other skeletal...
Read articleAcanthosis nigricans (AN) is a skin condition characterized by abnormally increased coloration (hyperpigmentation) and “velvety” thickening (hyperkeratosis) of the skin, particularly of skin fold regions, such...
Read articleDipetalonemiasis/Acanthocheilonemiasis is a rare tropical infectious disease caused by a parasite known as Acanthocheilonema perstans, which belongs to a group of parasitic diseases known as filarial...
Read articleAblepharon-macrostomia syndrome (AMS) is a rare genetic disorder characterized by absent or underdeveloped eyelids (ablepharon or microblepharon) and a wide mouth (macrostomia). Characteristics mainly involve the...
Read articleKlinefelter Syndrome (47, XXY) is a chromosomal variation in males in which one extra X chromosome is present, resulting in a 47, XXY karyotype. The extra...
Read articleUlnar mammary syndrome is a rare inherited disorder characterized by abnormalities of the bones of the hands and forearms in association with underdevelopment (hypoplasia) and dysfunction...
Read articleJacob’s syndrome—also called 47,XYY syndrome—is a genetic condition that affects boys and men who have one extra Y chromosome in their cells. Most males have 46...
Read articlePost-Acute COVID-19 Syndrome (PACS)—also called Long COVID and PASC (post-acute sequelae of SARS-CoV-2 infection). This is the name most guidelines and journals use for the condition...
Read articleThe inflammatory markers are a disparate set of medical tests that are often prescribed by doctors to identify or investigate the infection, inflammation, autoimmune rare disease, tumor,...
Read articleAutoinflammatory syndromes are a group of disorders characterized by recurrent episodes of inflammation due to an abnormality of the innate immune system, which is the first...
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