Chitayat-Hall syndrome (CHS) causes contractures of hands and feet, intellectual disability and growth hormone (GH) deficiency, among other features. GH deficiency leads to poor growth and may cause recurrent episodes of hypoglycemia, which can damage the developing brain if untreated. We identify mutations in MAGEL2, located within the Prader-Willi syndrome region at 15q11-q13, as the cause of CHS. Our findings indicate that CHS and Schaaf-Yang syndrome are the same condition. We describe the diagnosis and treatment of GH deficiency in 6 affected patients. GH deficiency is an important complication of this condition, and timely diagnosis and treatment can lead to improved growth and prevention of hypoglycemia. (By Dr. Rebekah Jobling, http://jmg.bmj.com/content/early/2018/03/29/jmedgenet-2017-105222 )