The broad autism phenotype: a complementary strategy for molecular genetic studies of autism.

The genetic liability for autism appears to be expressed not only as the full syndrome of autism, but in milder, qualitatively similar characteristics that collectively have been referred to as constituting the broad autism phenotype. Identification of components of the broad autism phenotype that segregate independently in relatives of autistic individuals may provide an index of genes that, when present together, may interact to produce autism. Inclusion of information on the broad autism phenotype in relatives, in linkage studies of autism, may provide a potentially important, complementary approach for detecting the genes causing this condition.