SMS is a developmental disorder that is most often caused by a deletion in chromosome 17p11.2 that encompasses the retinoic acid-induced 1 (RAI1) gene.
Alterations in RAI1 copy number has been also linked to a number of neurodevelopmental disorders including Autism Spectrum Disorder (Autism). In fact, 90% of SMS patients meet diagnostic criteria for Autism at one point in their lives.
One of the most common symptoms of SMS is a severe sleep disorder associated with significant disruption in the lives of patients and their families.
Patients with SMS present with a number of physical, mental and behavioral problems.