The ectodermal dysplasias are inherited disorders that involve defects in the hair, nails, sweat glands and teeth. When a person has at least two types of abnormal ectodermal features—for example, malformed teeth and extremely sparse hair—the individual is identified as being affected by ectodermal dysplasia.
The conditions are a remarkably diverse group of disorders which may also affect other parts of the body. The ectoderm contributes to the formation of the lens of the eye, parts of the inner ear, the fingers and toes, and nerves, among others. Therefore, ectodermal dysplasia may cause these parts of the body to develop abnormally.
There are more than 150 different types of ectodermal dysplasias. Symptoms range from mild to severe. Only in rare cases does ectodermal dysplasia affect lifespan and very few types involve learning difficulties.