Editor—The interstitial deletion of the short arm of chromosome 17 was first reported in 1982 by Smithet al 1 in two unrelated patients presenting with congenital heart defects and facial clefts. Since then a clinically recognisable phenotype has been described,2-8 including brachycephaly, midfacial hypoplasia, a broad, flat nasal bridge, prominent lower jaw, inverted V shaped upper lip with a prominent cupid’s bow, hoarse voice, speech delay, psychomotor and growth retardation, and behavioural problems which are often characteristic. Behavioural problems are present in most patients and include self-injurious behaviour such as hand biting, head banging, onychotillomania (pulling out finger and toenails), and polyembolokiolamania (the insertion of foreign bodies into body orifices).9 A characteristic self hugging behaviour has also been described.10 Hearing loss, ocular problems,11 12 scoliosis, and sleep disturbance13 also occur.

The estimated frequency of cardiac lesions is 37%4 and those which have previously been described include atrial septal defects, ventricular septal defects, tricuspid and mitral valve stenoses or regurgitation, mitral valve prolapse, subvalvular aortic stenosis, and supravalvular pulmonary stenosis.2 4

The estimated frequency of SMS is 1 in 25 000 but this may be an underestimate, as if the deletion is small it may be missed on routine cytogenetic analysis and may only be detectable by fluorescence in situ hybridisation (FISH).

Diagnosis of SMS is often delayed until the characteristic physical and behavioural phenotypes become evident and …