DISCUSSION
MAGEL2 is a paternally expressed, maternally imprinted, protein-coding gene located on chromosome 15. MAGEL2 is one of the genes that falls into the paternally expressed region of chromosome 15 (15q11-q13) known to result in Prader-Willi Syndrome (PWS, MIM: #176270)8. Prader-Willi Syndrome is characterized by hypotonia, feeding difficulties followed by hyperphagia later, failure to thrive, developmental delay and, hypogonadism in males.9 Schaaf-Yang Syndrome (SYS) has a great deal of clinical overlap with PWS in that affected individuals often have hypotonia, feeding difficulties, failure to thrive, developmental delay/intellectual disabilities, and hypogonadism.8However, individuals with Schaaf Yang are more likely to have congenital contractures ranging from mild to severe, autistic spectrum disorder and hypopituitarism.10,11,12 Hyperphagia which is common in PWS is not a common feature of SYS. Truncating mutations inMAGEL2 appear to be more consistent with classic SYS phenotype, whereas whole gene deletions including the promoter region inMAGEL2 have been found to have milder phenotypic consequences.13,14 This may be due to a dominant negative effect of the truncated protein or due to ‘leaky’ expression of the maternal copy of MAGEL2 in whole gene deletion cases which has been suggested in mice studies 9,12.