PMP22 and disorder of sexual differentiation: Dominant de novo mutations in peripheral myelin protein 22 (PMP22; Roa, Dyck, Marks, Chance, & Lupski, 1993), myelin protein zero (MPZ; Hayasaka et al., 1993; Warner et al., 1998) or early growth response 2 (EGR2) are the most common causes of DSD.