EDA and hypohidrotic ectodermal dysplasia: It has been demonstrated that HED is caused by pathogenic variants in several genes, including EDA (OMIM 300451), which is located on chromosome Xq12-q13.3 and encodes the ligand ectodysplasinA-A1 (EDA-A1), EDAR (OMIM 604095), which is located on chromosome 2q11–13 and encodes the ectodysplasinA-A1 receptor, and EDARADD (OMIM 606603), which is located on chromosome 1q42-q43 and regulates the structure of EDAR-associated death domain protein.