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 articleAnkyloblepharon-ectodermal dysplasia-cleft lip/palate (AEC) syndrome, which is also known as Hay-Wells syndrome, ankyloblepharon-ectodermal defects-cleft lip/palate, ankyloblepharon-ectodermal dysplasia-cleft lip/palate syndrome, Hay-Wells syndrome, Rapp-Hodgkin syndrome is a rare...
Read articleAdult-onset Still’s disease (AOSD) is a rare inflammatory disorder that can affect the entire body (systemic disease). The cause of the disorder is unknown (idiopathic). Affected...
Read articleAdult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) also known as hereditary diffuse leukoencephalopathy with spheroids (HDLS) and pigmentary orthochromatic leukodystrophy (POLD), is a rare, progressive neurological disease that...
Read articleAdult polyglucosan body disease (APBD) is a rare, genetic disorder characterized by a deficiency of the glycogen-branching enzyme, progressive pyramidal paraparesis, and distal sensory deficit in...
Read articleAdult neuronal ceroid lipofuscinosis (ANCL) is a general term for several rare genetic disorders that belong to a group of progressive, degenerative neurometabolic disorders known as...
Read articleADNP syndrome, also known as Helsmoortel-Van Der Aa syndrome, is a neurodevelopmental genetic disorder caused by changes (mutations) in the ADNP gene. These mutations occur spontaneously in the...
Read articleAdie syndrome, or Holmes-Adie syndrome, is a rare neurological disorder affecting the pupil of the eye. In most patients, the pupil is larger than normal (dilated)...
Read articleAdenylosuccinate lyase deficiency is an inherited metabolic disorder that is characterized by three categories (fatal neonatal form, type I, and type II), each of which has...
Read articleADCY5-related dyskinesia is a neurologic disorder with a variety of movement abnormalities. Dyskinesia means that affected individuals have trouble controlling voluntary movements. Voluntary movements are any...
Read articleAdams-Oliver syndrome (AOS) is a rare inherited condition present at birth that involves changes to the limbs and scalp. Symptoms may include areas of missing skin...
Read articleAcute promyelocytic leukemia (APL) is a blood cancer characterized by a marked increase in a type of white blood cells known as promyelocytes, a type of...
Read articleAcute intermittent porphyria (AIP) is a rare metabolic disorder that is characterized by partial deficiency of the enzyme hydroxymethylbilane synthase (also known as porphobilinogen deaminase). This...
Read articleAcute eosinophilic pneumonia (AEP) is a rare disorder characterized by the rapid accumulation of eosinophils in the lungs (pulmonary eosinophilia). Eosinophils are a type of white...
Read articleAcute disseminated encephalomyelitis (ADEM) is a neurological, immune-mediated disorder in which widespread inflammation of the brain and spinal cord damages tissue known as white matter. White...
Read articleACTH deficiency arises as a result of decreased or absent production of adrenocorticotropic hormone (ACTH) by the pituitary gland. A decline in the concentration of ACTH...
Read articleAcromicric Dysplasia is a condition characterized by severely short stature, short limbs, stiff joints, and distinctive facial features and an extremely rare inherited disorder characterized by...
Read articleAcromesomelic dysplasia is an extremely rare, inherited, progressive skeletal disorder that results in a particular form of short stature known as short-limb dwarfism. The disorder is...
Read articleAcrodysostosis is a rare genetic disorder characterized by skeletal malformations, growth delays, short stature, and distinctive facial features caused, in part, by underdeveloped (hypoplastic) certain facial...
Read articleAcrodermatitis enteropathica (AE) is a disorder of zinc metabolism caused by a defect in the absorption of zinc, that occurs in one of three forms: an...
Read articleAcrocallosal syndrome, Schinzel type is a rare genetic disorder that is apparent at birth (congenital). Associated symptoms and findings may be variable, including among affected members...
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