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 articleGalactosialidosis is a very rare genetic disease in which the “recycling centres” inside cells, called lysosomes, do not work properly. [1] In healthy people, lysosomes use...
Read articleCombined deficiency of sialidase and beta-galactosidase is a rare inherited disease where two important “clean-up” enzymes inside the cell do not work properly. Doctors usually call...
Read articleFamilial multiple coagulation factor deficiency is a group of rare inherited bleeding disorders where a person has low levels of two or more blood-clotting proteins at...
Read articleAmerican mountain tick fever is another name for a disease called Colorado tick fever. It is a rare sickness caused by a virus that lives inside...
Read articleMicrophthalmia, syndromic type 14 is a very rare genetic disease that affects the eyes, bones, and body growth. In this condition, one or both eyes are...
Read articleMicrophthalmia-coloboma-rhizomelic skeletal dysplasia is a very rare genetic syndrome that affects eye development, bone growth, and sometimes the brain and other organs. “Microphthalmia” means one or...
Read articleColobomatous microphthalmia-rhizomelic dysplasia syndrome is a very rare genetic condition that starts when the baby is still in the womb. In this syndrome, the eyes do...
Read articleColobomatous microphthalmia–obesity–hypogenitalism–intellectual disability syndrome is a very rare genetic condition. In this syndrome, both eyes are small (microphthalmia), one eye usually has a gap or missing...
Read articleMACOM syndrome means “macrophthalmia, colobomatous, with microcornea.” It is a very rare genetic eye problem. In this condition, the clear front window of the eye (cornea)...
Read articleColobomatous macrophthalmia-microcornea syndrome is a very rare eye condition that is present from birth and runs in families. In this condition, the clear front window of...
Read articleCongenital optic disc coloboma is a birth defect of the optic nerve head (the place where the nerve enters the back of the eye). In this...
Read articleSorsby syndrome is a very rare genetic disease that affects both the eyes and the fingers and toes from birth. The main problems are a special...
Read articleColoboma of macula–brachydactyly type B syndrome is a very rare genetic condition that affects both the eyes and the hands/feet from birth and lasts for life....
Read articleBone fragility-craniosynostosis-proptosis-hydrocephalus syndrome is an extremely rare genetic disease that mainly affects bones of the skull and the whole skeleton. Children have very weak bones that...
Read articleCole-Carpenter syndrome is an extremely rare genetic bone disease. It affects less than a few dozen people in the world. In this condition, the bones are...
Read articleCRLF1-related cold-induced sweating syndrome, including Crisponi syndrome, is a very rare genetic disease that affects how the body controls temperature, sweating, face and limb shape, and...
Read articleCold-induced sweating syndrome 1 (CISS1) is a very rare genetic disease that affects how the body controls temperature and how the nerves and face develop. In...
Read articleSohar-Crisponi syndrome is a very rare genetic disease that mainly affects babies and children. It belongs to a family of problems called cold-induced sweating syndromes, which...
Read articleCrisponi syndrome is a very rare genetic disease. It starts in newborn babies. The baby has sudden strong muscle contractions, mainly in the face, neck, and...
Read articleCold-induced sweating syndrome (CISS) is a very rare genetic disease. It mainly affects how the body controls temperature, sweating, face muscles, and bones. Children with this...
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