Behavioural and emotional disturbance in fragile X syndrome.

A range of behaviours has been postulated as specific manifestations of the Fragile X (fra(X)) syndrome. This study examines a broad range of behaviours in subjects with fra(X) syndrome and in control individuals. It was designed to take account of methodological factors which may account for differing findings in previous studies. Subjects were 48 children, adolescents, and young adults with fra(X) syndrome. They were compared with a large community epidemiological sample (N = 454) of persons with mental retardation (M.R.), matched for age, sex, and IQ. Behavioural problems were studied using the Developmental Behaviour Checklist, an instrument of established reliability and validity in the evaluation of behavioural and emotional disturbance in children and adolescents with mental retardation. Fragile X subjects had more shyness and avoidance of eye contact and less antisocial behaviour. Further methodological issues pertaining to studies of behaviour phenotype in general are discussed.