 Mutations in the "EDA", "EDAR", and "EDARADD" genes cause hypohidrotic ectodermal dysplasia.The "EDA", "EDAR", and "EDARADD" genes provide instructions for making proteins that work together during embryonic development.These proteins form part of a signaling pathway that is critical for the interaction between two cell layers, the ectoderm and the mesoderm.