PMD is caused by mutations involving the PLP1 gene that encodes the myelin protein proteolipid protein 1 (PLP1) and the spliced variant DM20. The c.251C > A mutation, located within the second hydrophobic transmembrane domain of PLP1, has not been previously described. Mutations in the same region of the protein, including c.247G > A and c.254 T > C mutations causing a p.Gly83Arg and p.Leu85Arg amino acid substitutions respectively, have been shown to cause connatal form of PMD [11, 12].