Early behavioural manifestation of Smith-Magenis syndrome (del 17p11.2) in a 4-month-old boy.

Objective: There is little systematic data on early neurodevelopmental functioning of infants with Smith-Magenis syndrome, since early diagnosis is rare.

Methods: A boy with cytogenetically confirmed Smith-Magenis syndrome was videotaped at 4 months and 1 week of age. His posture and spontaneous movements were analysed without knowing the diagnosis.