[9] Nucleotide mutations in the ectodysplasin A (EDA) gene, which is located in Xq12-q13.1,[2,10] are the main causes of XLHED (OMIM: 305100) features.[2,11,12] The EDA signaling pathway plays an important role in embryonic ectodermal development.[13,14] Mutations in genes involved in this pathway disturb the interaction between surface-located epithelial cells and the underlying mesenchyme[15] during embryonic development, which causes alterations of the initiation, formation, and differentiation of skin appendages. Here, EDA is linked to X-linked hypohidrotic ectodermal dysplasia.