Ectodermal Dysplasia

Ectodermal dysplasias (EDs) form a diverse group of inherited disorders characterized by a congenital defect in two or more ectodermal structures, one of which involves hair, teeth, nails, or sweat glands. Other organs derived from embryonic ectoderm include mammary glands, CNS, external ear, melanocytes, cornea, conjunctiva, and lacrimal apparatus. Having accepted this definition of ectodermal dysplasia, PINHEIRO and FREIRE-MAIA subclassified the ectodermal dysplasia into groups depending on the presence of hair(1), nail(2), the tooth(3) or sweat gland(4) abnormality.

This classification also is known as the 1-2-3-4 system, designated conditions into various groups based on the constellation of the ectodermal structures affected. Another way to classify ED is based on molecular defects. The latest classification is a working system that has integrated clinical, genetic, and functional pathway-based data. This review summarizes the key clinical and genetic features of few ectodermal dysplasias with a known molecular basis.