EDARADD and hypohidrotic ectodermal dysplasia: It has been demonstrated that HED is caused by mutations of several genes: ED1, encoding a ligand-ectodysplasinA-A1 (EDA-A1), EDAR, coding for ectodysplasinA-A1 receptor, EDARADD, programming the structure of EDAR-associated death domain protein and NEMO whose protein product, NFκB essential modulator (NEMO), is necessary for an indirect activation of nuclear factor κB (NFκB).