Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are the most studied genomic-imprinting disorders mapped to chromosome 15q11-q13. Lack of a functional paternal copy of 15q11-q13 causes PWS. Additionally, it has been reported that MECP2 deficiency leads to decreased expression of UBE3A. PWS and AS have characteristic neurologic, developmental, and behavioral phenotypes plus other structural and functional abnormalities. The behavioral and endocrine disorders are more severe in PWS, including obsessive-compulsive symptoms and hypothalamic insufficiency.
