A strong genetic contribution to the spectrum of pervasive developmental disorders is widely accepted, yet genetic factors underlying a substantial portion of the heritability remain elusive. A proportion of the genetic risk for autism spectrum disorders (ASD) is attributable to both common polymorphisms, which are alterations in gene sequence that vary across a population, and rare structural variations, which result in a net gain or loss of genetic material. What is not clearly addressed by current approaches is the potential contribution of a third type of genetic alteration called balanced chromosomal rearrangements, which can truncate, delete, or otherwise inactivate specific genes. The incidence of balanced chromosomal rearrangements are substantially increased in ASD patients compared to the general population, yet their impact is largely unknown as current methodology does not allow for rapid and accurate detection of these genomic events. In this study, researchers will use recent advances in "next-generation" sequencing to identify genes disrupted in ASD patients with apparently balanced chromosomal rearrangements. The methodology will also enable assessment of small copy number variations, another important source of genetic variation and causation in ASD. Secondary molecular analysis will then be used to define the pathogenic mechanisms. The studies will culminate in characterization of a series of future ASD targets for biological and pharmacological investigation.