For example, Muthusamy et al. [21] summarized the literature regarding maternal disomy 15 and reported a second case of congenital ichthyosis in Prader-Willi syndrome with involvement of the ceramide synthase (CERS3) gene on chromosome 15 and two homozygous pathogenic variants in an adult female with PWS having maternal disomy 15. The gene discussed is CERS3; the disease is Prader-Willi syndrome.