This is a Clinical Investigator Award, providing an opportunity for a medical investigator to develop into an independent researcher. The objective of the research plan is to identify and characterize candidate genes at the neural synapse for autism spectrum disorders (ASDs). Dr. Gupta identified Piccolo (PCLO) as a candidate gene when it was found to be transected by a chromosomal inversion in a patient with ASD. PCLO, a major component of the presynaptic cytoskeletal matrix, has diverse functional domains and binds a wide variety of molecules. It appears to have a key role in orchestrating the sequence of events from synaptic vesicle clustering at the active zone to exocytosis and endocytosis. It is an intriguing finding given that a number of candidate genes for ASD, such as the NLGNs, NRXN1, and SHANK3, are converging at the neural synapse, indicating that the synapse is a site of damage. As the list of candidate genes grows, it has become critical to comprehensively analyze the functional consequences of patient mutations in order to start unraveling the pathophysiology of the disorder. With that purpose, this project will characterize the precise genetic abnormalities in the index case, determine the extent of PCLO's involvement in the larger patient population through sequence and CNV analysis, characterize the functional consequences of patient mutations in PCLO, and identify additional synaptic genes which contribute to the disorder. The goal is to elucidate the neural systems involved in the pathophysiology of ASDs, which will provide insights into the development of targeted treatments.