ED is genetically heterogeneous, and the most common form in humans is X-linked anhidrotic/hypohidrotic ectodermal dysplasia (XLHED) caused by variants in the EDA gene encoding ectodysplasin A (Kere et al. 1996; OMIM #305100). The gene discussed is EDA; the disease is X-linked hypohidrotic ectodermal dysplasia.