Autism and the pervasive developmental disorders.

Our understanding of childhood autism and the related pervasive developmental disorders continues to advance in many areas. Nevertheless, the heterogeneity of phenotypic expression presents many challenges, not least to efforts to ascertain the prevalence of the disorders. There is now wide agreement on, and reliable application of, the diagnostic criteria for childhood autism, but there is less agreement on and less reliable application of the criteria for the related disorders atypical autism, pervasive developmental disorder-unspecified and Asperger's syndrome. Evidence about genetic associations indicates that several genes are involved in creating susceptibility to the disorder, and the first steps to identify susceptibility loci have begun. Neuroanatomical models have yet to receive consistent support but early signs of promising advances have been made in pharmacological interventions, and adequate evaluation of behavioural intervention programmes is now underway.