Hypohidrotic Ectodermal Dysplasia
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NORD is very grateful to Jing Wang, NORD Editorial Intern from the University of Notre Dame, and J Timothy Wright, DDS, MS, Distinguished Bawden Professor, Department of Pediatric Dentistry, University of North Carolina, for assistance in the preparation of this report.
Synonyms of Hypohidrotic Ectodermal Dysplasia
- Anhidrotic Ectodermal Dysplasia
- Christ-Siemens-Touraine Syndrome
- CST Syndrome
- No subdivisions found.
Hypohidrotic ectodermal dysplasia (HED) is a rare inherited multisystem disorder that belongs to the group of diseases known as ectodermal dysplasias. Ectodermal dysplasias typically affect the hair, teeth, nails, sweat glands, and/or skin. HED is primarily characterized by partial or complete absence of certain sweat glands (eccrine glands), causing lack of or diminished sweating (anhidrosis or hypohidrosis), heat intolerance, and fever; abnormally sparse hair (hypotrichosis), and absence (hypodontia) and/or malformation of certain teeth. Many individuals with HED also have characteristic facial abnormalities including a prominent forehead, a sunken nasal bridge (so-called "saddle nose"), unusually thick lips, and/or a large chin. The skin on most of the body may be abnormally thin, dry, and soft with an abnormal lack of pigmentation (hypopigmentation). However, the skin around the eyes (periorbital) may be darkly pigmented (hyperpigmentation) and finely wrinkled, appearing prematurely aged. In many cases, affected infants and children may also exhibit underdevelopment (hypoplasia) or absence (aplasia) of mucous glands within the respiratory and gastrointestinal (GI) tracts and, in some cases, decreased function of certain components of the immune system (e.g., depressed lymphocyte function, and rarely cellular immune hypofunction), potentially causing an increased susceptibility to certain infections and/or allergic conditions. Many affected infants and children experience recurrent attacks of wheezing and breathlessness (asthma), respiratory infections; chronic inflammation of the nasal passages (atrophic rhinitis), scaling, itchy (pruritic) skin rashes (eczema), and/or other findings.
HED is usually inherited as an X-linked recessive genetic trait and is caused by a mutation in the ectodysplasin-A (EDA) gene; in such cases, the disorder is fully expressed in males only. However, females who carry a single copy of the disease gene (heterozygote carriers) may exhibit some of the symptoms and findings associated with the disorder. These may include absence and/or malformation of certain teeth, sparse hair, and/or reduced sweating. HED can also be inherited as an autosomal dominant or autosomal recessive genetic trait, caused by mutations in the EDAR or EDARADD genes. In such cases, the disorder is fully expressed in both males and females.
Organizations related to Hypohidrotic Ectodermal Dysplasia
(Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder [e.g., dysplasia-associated characteristics of the skin, hair, and teeth; mental retardation; etc.].)
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