Ectodermal dysplasia

A genetic disorder in which there is abnormal development of the skin and associated structures (the hair, nails, teeth, and sweat glands). The most dangerous problem occurs in cases with decreased sweating due to absence of the sweat glands. Affected persons have trouble controlling fevers and being in a warm environment. The hair may also be absent or sparse. The skin tends to be thin and light in color. Problems with the lining inside the nose predispose to chronic nasal infections. The teeth may be notably absent or develop abnormally. There are a number of different types of ectodermal dysplasia. X-linked anhidrotic (non-sweating) ectodermal dysplasia is most common. As an X-linked trait, it mainly affects males. There is also an autosomal dominant form affecting males and females alike. The term "ectodermal dysplasia" refers to the abnormal development (dysplasia) of structures derived from the ectoderm, one of the germ cell layers in the embryo.

* * *

any of a group of hereditary disorders involving absence or deficiency of tissues and structures derived from the embryonic ectoderm, such as teeth, hair, nails, and certain glands; it is also a component of various syndromes, including anhidrotic and hidrotic ectodermal dysplasia and EEC syndrome.