The great volume of genetic data in the Simons Simplex Collection offers many opportunities to study the complex heritability of the disorder. Matthew State at Yale University is heading up a large, multi-institutional study that aims to scour the collection for autism-related genes. Each family analyzed for the collection comprises only one individual with autism; neither the parents nor the siblings are affected. This suggests that some of the genetic defects in the affected individuals are likely to be spontaneous and non-inherited. As these types of genetic changes are rare in unaffected individuals, State and colleagues plan to focus on identifying these spontaneous variants as a clue to the location of autism-related genes. The researchers plan to sweep through each genome using the Illumina analysis platform, seeking out chromosomal regions that are duplicated or deleted in an affected family member but are normal in their relatives. They plan to then sequence genes within these promising segments in an effort to identify additional mutations that can help confirm their relationship to autism. The researchers then plan to further test any associations they identify in an independent sample of families. State and colleagues have hypothesized that many different types of variations in the genome will ultimately be found to contribute to autism spectrum disorders. They propose a series of additional studies exploring associations between both rare and common inherited genetic variants and traits of autism. This collaborative effort promises to help provide a comprehensive view of the genetic factors contributing to autism.