A disruption of the balance between the activity of excitatory neurotransmitters (which increase neural activity) and inhibitory neurotransmitters (which decrease neural activity) may be involved in autism. The principal excitatory neurotransmitter, glutamate, is counteracted by the activity of inhibitory neurotransmitters. Disregulation of either neurotransmitter system results in abnormal levels of neural activity. Mutations in genes involved in glutamate neurotransmission could lead to this kind of imbalance, and therefore confer a risk of autism. In the present study, Dr. Wang and colleagues will conduct a high-throughput genetic screen in a cohort of autistic patients, looking for DNA sequence variants in 38 genes known to be involved in glutamate neurotransmission. If the hypothesis that glutamate is involved in autism is correct, they expect to find multiple rare sequence variants of these genes in autistic patients, compared to a non-autistic control sample. This research may clarify the role of glutamate in autism, as well as identify new genetic risk factors and potential drug targets for the treatment and prevention of autism.