Truncating mutations in the MAGEL2 gene were identified previously in two distinct conditions, the Schaaf-Yang syndrome, a relatively mild condition with some resemblance to the Prader-Willi syndrome (see ref. 10 for further comparisons), and in patients with a severe form of arthrogryposis with reduced fetal movement and perinatal death8. Here, MAGEL2 is linked to Schaaf-Yang syndrome.