[Smith-Magenis syndrome]

The main features of the Smith-Magenis syndrome include broad flat midface, brachycephaly, broad nasal bridge, brachydactyly, hoarse deep voice, speech and developmental delay, and behavioral anomalies. This syndrome is due to interstitial deletion of chromosome 17p11.2.

A 7-year-old girl was admitted for mental retardation. Clinical examination showed brachycephaly, broad flat midface, broad nasal bridge, malar hypoplasia, brachydactyly, decreased or absent deep tendon reflexes, and hoarse deep voice. She had a mild deafness, behavioral problems, and sleep disturbances. Chromosome analysis on lymphocytes identified a microdeletion of one chromosome subband 17p11.2. Molecular studies indicated loss of maternal allele.

The Smith-Magenis syndrome is probably underdiagnosed because of its usually mild clinical features. High-resolution chromosome analysis is needed for diagnosis.