Neurexin 1 (NRXN1) was recently implicated as an autism susceptibility gene. The association is intriguing because it interacts with neuroligin-3 and SHANK3, two other genes previously found to generate risk for autism and mental retardation, at synaptic junctions to help regulate synapse formation. Dr. Gusella and his colleagues plan to examine NRXN1 in samples from AGRE and samples collected by collaborators for mutations or variations that could disrupt its function and determine if it plays a role in a larger proportion of autism cases. In addition, since the samples will be clinically well characterized, there is also an opportunity to establish a more robust correlation between genetic variation and clinical presentation. What this means for people with autism: This study could determine the impact of NRXN1 variation on autism risk and a better sense of its frequency in the autism community. Understanding how these variants affect protein function and synaptogenesis could shed light on the underlying disease mechanism.