Schaaf-Yang syndrome

Schaaf-Yang syndrome (SYS) is a rare neurological disorder caused by a disruption in the MAGEL2 gene. Schaaf-Yang syndrome shares a lot of overlap with another genetic disorder, called Prader-Willi syndrome (PWS).


Both SYS and PWS can lead to hypotonia (low muscle tone), developmental delay/intellectual disability, sleep apnea, and feeding difficulties. However, there are important differences between the two syndromes, as SYS patients have a higher prevalence of autism and joint contractures.

There are currently over 160 known cases of SYS worldwide.

What are the features of SYS?

• Cognitive and behavioral Features: developmental delay/intellectual disability, autism spectrum disorder, and behavioral abnormalities (impulsivity, compulsivity, stubbornness, etc.)
• Physical traits: hypotonia, joint contractures, short stature, small hands/feet, scoliosis/kyphosis.
• Facial features: short noses, bushy eyebrows, underbite in jaw.
• Eye features: strabismus, estropia, myopia.
• Gastro-intestinal: Feeding difficulties, especially during infancy, sometimes a need for special feeding techniques (Gtube), gastroesophageal reflux (GERD), chronic constipation.
• Sleep: sleep apnea and altered circadian rhythm.

Is there a cure?

Currently, there is no cure to treat Schaaf-Yang syndrome. However, with proper management and early intervention, much can be done to improve the lives of patients with SYS. At present, this should include physical therapy, occupational therapy, and speech therapy, as well as ABA therapy if autism is present.

Growth hormone therapy may be considered if a growth hormone deficiency is identified. There are also surgeries to improve joint contractures, and surgeries/corrective lenses to address eye abnormalities.