Developmental and behavioural disturbances in 13 boys with fragile X syndrome.

Developmental and behavioural aspects were studied in 13 boys aged 2.6-12.5 years from three families with the fragile X syndrome. The following observations were made. Moderate to severe retardation was present in all boys; non-verbal IQs ranged between 25 and 67 (mean 46 +/- 14); IQ and age were negatively correlated (P less than 0.01). Language development was grossly delayed in all boys; most had severe articulation problems. Imitative and symbolic play (e.g. doll play) were strikingly retarded as compared to abstract play (e.g. block design). Autistic features such as no use of eye contact, stereotyped movements and echolalia were found in 9/13 boys; the same number showed aggressive behaviour. General activity was reduced during the 1st year of life; most boys became very hyperactive during the second year; and short attention span and increased distractability were observed in all. Motor development was mildly delayed; all boys were clumsy and moderately hypotonic. The fragile X syndrome ought to be considered in retarded boys with a dissociated developmental pattern, in particular a striking delay in language and play development, and autistic features.