Hypohidrotic ectodermal dysplasia.

We report three children with hypohidrotic ectodermal dysplasia (HED), which includes two sisters with unaffected parents (and therefore likely autosomal recessive inheritance of HED) and an unrelated boy. Each patient presented with hypohidrosis, sparse hair, oligodontia with conical teeth, periorbital hyperpigmentation, eczematous dermatitis, and facial features that include frontal bossing, a saddle nose, and prominent lips. HED is caused by defects in the ectodysplasin signal transduction pathway. Mutations in the gene encoding the ligand ectodysplasin A (EDA) underlie classic, X-linked recessive HED, whereas mutations in the genes encoding the EDA receptor and (less frequently) the adaptor protein that associates with the EDA receptor's death domain result in autosomal dominant and autosomal recessive forms of HED.