Current consensus on autism genetics is that multiple genes are likely to be involved. It is possible that different autistic individuals could harbor different combinations of affected genes, leading to variations in clinical presentation, including nature and severity of deficits. In this study, Dr. Cook and his colleagues will try to establish correlation between known genotypes with specific phenotypes, which could help define autistic subtypes. In addition, by exploring gene-gene interaction, Dr. Brune hopes to associate specific combinations of genotypes with increased risk for autism. What this means for people with autism: A better understanding of how genetic variations contribute to autism risk as well as different phenotypes would facilitate the identification of autism subtypes which could impact treatment selection.