IGFBP2 and Prader-Willi syndrome: Although selection bias is a significant concern, and this region is known as a susceptibility region, previous work suggested that a POE does exist in CHD involving the 15q11.2 BP1-BP2 microdeletion as well as in well-characterized imprinting disorders such as Prader-Willi syndrome resulting from a paternal 15q11-q13 deletion or maternal uniparental disomy 15 [36].