A group of hereditary disorders involving tissues and structures derived from the embryonic ectoderm. They are characterized by the presence of abnormalities at birth and involvement of both the epidermis and skin appendages. They are generally nonprogressive and diffuse. Various forms exist, including anhidrotic and hidrotic dysplasias, focal dermal hypoplasia, and aplasia cutis congenita.
Ectodermal dysplasia refers to a group of genetic disorders that involve abnormalities in the layer of cells known as the ectoderm. During prenatal development, the ectoderm is the outer layer of cells in the fetus that grow into the skin, hair, nails, teeth, nerve cells, sweat glands, and parts of the ear, eye, and other organs (National Foundation for Ectodermal Dysplasias [NFED] Scientific Advisory Board, 2000). The prevalence of ectodermal dysplasias-of all types is estimated to be as high as 7 of every 10,000 births (NFED Scientific Advisory Board, 2000).
A group of rare inherited disorders in which there are defects in the function or development of glands, hair, nails, or teeth, i.e., organs that originate embryologically in the ectoderm.