Abstract
Although Angelman (AS) and Prader‐Willi (PWS) syndromes are human genetic disorders with distinctly different developmental and neurobehavioural phenotypes, they both have abnormalities in inheritance of chromosome 15q11–q13. Whether AS or PWS arises depends on the parental origin of a deletion or uniparental disomy (the inheritance of 2 copies of a genetic locus from only one parent) for 15q11–q13. Normal development requires a genetic contribution for this genetic region from both a male and female parent. The dependence on parental origin implies that genes in human 15q11–q13 have distinct functions depending upon epigenetic, parent‐of‐origin differences, known as genomic imprinting. Here, I review the role of uniparental disomy and genomic imprinting in the pathogenesis of AS and PWS, and briefly discuss phenotype‐genotype correlations using candidate genes and mouse models, in particular for hypopigmentation.