EDARADD

Hypohidrotic ectodermal dysplasia

Fewer than 10 mutations in the EDARADD gene have been found to cause hypohidrotic ectodermal dysplasia, the most common form of ectodermal dysplasia. Starting before birth, ectodermal dysplasias result in the abnormal development of the skin, hair, nails, teeth, and sweat glands. Hypohidrotic ectodermal dysplasia is characterized by a reduced ability to sweat (hypohidrosis), sparse scalp and body hair (hypotrichosis), and several missing teeth (hypodontia) or teeth that are malformed. EDARADD gene mutations are an infrequent cause of hypohidrotic ectodermal dysplasia, accounting for only about 1 percent of all cases.

Most of the EDARADD gene mutations associated with hypohidrotic ectodermal dysplasia change single protein building blocks (amino acids) in the receptor protein. These changes occur in or near the death domain, preventing the EDARADD protein from interacting effectively with the ectodysplasin A receptor. As a result, the receptor cannot trigger the signals needed for ectoderm-mesoderm interactions in early development. Without these signals, hair follicles, teeth, sweat glands, and other ectodermal structures do not form properly, which leads to the characteristic features of hypohidrotic ectodermal dysplasia.