OCA2 and Prader-Willi syndrome: One was affected by OCA2 with PWS due to an atypical deletion (chr15: 22330347–26089649, approximately 3.8 Mb) on paternal chromosome 15 and a point mutation c.1327G>A (Val443Ile) in the p gene of maternal chromosome 15, and we performed prenatal diagnosis for family 1, which indicated that the fetus was a heterozygous carrier (c.1327G>A/G in the p gene) with a normal phenotype.