Smith-Magenis syndrome

Smith-Magenis syndrome, also known as 17p-microdeletion syndrome, is a genetic disorder caused in most cases by a spontaneous deletion of material from the short arm of chromosome 17, in the 17p11.2 region, which removes the RAI1 gene responsible for most of the condition's characteristic features; it is typically not inherited from a parent but arises de novo. It affects an estimated one in 15,000 to one in 25,000 people and produces distinctive facial features such as a broad face, deep-set eyes and a prominent jaw, along with intellectual disability, an inverted circadian rhythm that disrupts sleep, and self-harming behaviors including biting, head banging and skin picking. Affected individuals often have reduced sensitivity to pain and temperature, and may develop scoliosis or hearing loss. There is no cure; management relies on melatonin supplementation for sleep disturbance and behavioral therapies to address self-injury and other symptoms.