The Costello syndrome: a boy with thick mitral valves and arrhythmias.

A 3-year-old boy with Costello syndrome is reported. He had typical clinical features of the syndrome including severe postnatal growth retardation, poor sucking, mild developmental delay, a coarse characteristic facies, thick and loose skin of the hands and feet, sparse and curly hair, dark skin, and relative macrocephaly but lacked nasal papillomas. In addition, he had cardiac anomalies with extrasystoles and thick mitral valve tips. Mitral valve defects may be a clinical feature of the syndrome.