Ectodermal dysplasia comprises inherited disorders that are defined by primary defects in the development of two or more tissues derived from the embryonic ectoderm. The tissues primarily involved are the skin, hair, nails, exocrine glands, and teeth. Ectodermal dysplasias are congenital, diffuse, and non-progressive. To date, more than 192 distinct disorders have been described. The most common EDs are X-linked recessive Hypohidrotic ED (Christ-Siemens-Touraine syndrome) and hidrotic ED (Clouston syndrome). In these disorders, hair may be sparse, sweat glands rudimentary, teeth abnormal or absent, and nails brittle.