Mutations affecting signalling through the cell surface receptor EDAR (OMIM#604095), either by mutation of EDAR itself or of the genes encoding its interaction partners EDA or EDARADD, cause hypohidrotic ectodermal dysplasia (also known as anhidrotic ectodermal dysplasia or Christ-Siemens-Touraine syndrome) [2]. This evidence concerns the gene EDAR and hypohidrotic ectodermal dysplasia.