Autism in Down's syndrome: presentation and diagnosis.

Although autism is said to occur rarely with Down's syndrome, it may be more common in those persons with Down's syndrome who also show superimposed behavioural problems. In this brief report, the authors explore this possibility. They describe three patients with Down's syndrome who were referred for behavioural reasons and were found to have coexisting autism. They propose that a systematic study of the association of these two conditions may have implications on research and clinical practice.