SMITH–MAGENIS SYNDROME

Abstract

Smith-Magenis syndrome is a multisystem, multiple congenital anomaly/mental retardation syndrome caused by an interstitial deletion of chromosome 17p11.2. Many cases have been identified worldwide from a diversity of ethnic groups. The diagnosis is based on the clinical recognition of a unique and complex pattern of physical, developmental, and behavioral features, many of which are subtle in early childhood, becoming more distinctive with advancing age. There is a characteristic craniofacial appearance with rather close-set, deep-set eyes under heavy brows, a square jaw, and an unusual full, everted upper lip. Speech delay with or without hearing loss is common. Ocular abnormalities are frequently found and short stature with failure to thrive is often seen. There are variable levels of intellectual handicap and the neurobehavioral phenotype includes sleep disturbance with an inverted circadian rhythm of melatonin, self-injurious behaviors, stereotypies, and sensory integration disorders. Keywords: Smith-Magenis syndrome; microdeletion; interstitial deletion of chromosome 17p11.2; intellectual handicap; short stature; craniofacial dysmorphism; behavioral phenotype; self-injurious behavior; stereotypies