Contributor: Gordon K. Klintworth
Several types of ectodermal dysplasia are recognized and most are characterized by abnormally developed teeth (hypodontia), hair (hypotrichosis) and eccrine sweat glands (hypohidrosis). In some ectodermal dysplasias the teeth are not affected. Some ectodermal dysplasias are isolated disorders; others have associated clinical manifestations in other parts of the body. More than 100  syndromes with ectodermal dysplasia have been defined. They include X-linked hypohidrotic ectodermal dysplasia [ectodermal dysplasia - X-linked hypohidrotic], autosomal recessive anhidrotic/hypohidrotic ectodermal dysplasia [ectodermal dysplasia - autosomal recessive hypohidrotic], autosomal dominant ectodermal dysplasia [ectodermal dysplasia - autosomal dominant], ectodermal dysplasia type 1, ectodermal dysplasia type 2, ectodermal dysplasia type 3, ectodermal dysplasia type 4, focal facial dermal dysplasia type I , focal facial dermal dysplasia type II,  focal facial dermal dysplasia type III and focal ectodermal dysplasia.