MC1R variants modify the congenital phenotype of the rare genetic disorders oculocutaneous albinism type 2 (King et al., 2003) and large congenital melanocytic nevus (CMN; Kinsler et al., 2012), strongly suggesting a role for MC1R in utero at least in the presence of other mutations affecting pigment synthesis or MAP kinase signaling. This evidence concerns the gene MC1R and melanocytic nevus.