Gene effect in carriers of anhidrotic ectodermal dysplasia.

Anhidrotic Ectodermal Dysplasia In an extensive review of different forms of hereditary ectodermal dysplasia, Cockayne (I933) recognized two types of inheritance for the variety characterized by anhidrosis, hypotrichosis, and complete or partial anodontia. He postulated an X-linked recessive gene in families where males alone were affected and an autosomal dominant gene where females were involved. However, as pointed out by Levit (1936), females never exhibited the full syndrome, and the inheritance in all families reviewed by Cockayne was consistent with X-linkage. Many subsequent reports of males with X-linked anhidrotic ectodermal dysplasia have established a remarkably consistent phenotype. The outstanding feature is lack of sweating, as perceived by the patient and on external examination of the skin. This results from a gross but not absolute deficiency of sweat glands. Hair on the scalp and eyebrows is sparse and fine and usually lacking on the body surfaces though adults may develop a beard. Noneruption of teeth at either dentition may result in complete anodontia but more frequently a few malformed teeth are present. Lack of teeth provides one aspect of the characteristic facies which together with hypotrichosis, prominent bossing of the forehead, and typically depressed bridge of the nose renders affected males similar in appearance. The evidence for an autosomal dominant variety of anhidrotic ectodermal dysplasia remains inconclusive. Some confusion with the hidrotic variety is evident in certain reports. This latter form is characterized by hypotrichosis and dystrophy of the nails in association with normal sweating and