Schaaf-Yang syndrome is a neurologic disorder caused by a disruption of the MAGEL2 gene. The MAGEL2 gene is located on chromosome 15.

Each individual receives one copy of the gene from their biological mother and one from their biological father. The MAGEL2 gene is a “maternally imprinted” gene, which means the copy received from the mother has a mark that turns off the gene. The copy received from the father does not have that mark and is turned on.  Under normal circumstances, this is no problem.  But if the copy received from the father has a mutation (disruption) in the MAGEL2 gene, it may lead to symptoms of Schaaf-Yang syndrome.