Abstract: Objective　To explore the clinical characteristics of Smith-Magenis syndrome (SMS). Methods　The clinical data and the results of molecular genetics detection of SMS in a child were retrospectively analyzed and the related literature was reviewed. Results　A boy, aged 5 years and 9 months, suffered from psychomotor retardation. He had sleep disorders since childhood including trouble falling asleep and shortened sleep cycles. He also had neurobehavioral symptoms including hyperactivity and self-injurious behaviors including bumping head, scratching and yanking fingernails. The patient had special facial features such as low hairline, broad forehead, flat face, low nasal bridge, tented upper lip and enamel dysplasia, brachydactyly, short and broad hands. Head magnetic resonance imaging showed enlargement of cerebral ventricle and cavum septum pellucidum. Chromosome microarray analysis showed a deletion of 17p11.2 with a length of 3.07 Mb [arr 17p11.2 (17,143,150-20,213,815) ×1]. The molecular karyotype was ascertained as 46, XY and Smith-Magenis syndrome was diagnosed finally. Conclusions　For children with psychomotor retardation, distinct facial phenotype, sleep disorders, behavioral disorders, Smith-Magenis syndrome should be considered. Chromosomal microarry analysis contributes to the early diagnosis of SmithMagenis syndrome.

Key words: Smith-Magenis syndrome;　RAI1 gene;　chromosome microarray analysis