The purpose of this mentored Research Career Development Award is to support the career development of investigators who have made a commitment to focus their research endeavors on patient-oriented research. The trainee's research focuses on the genetics of restricted repetitive behavior (RRB), one of the core features of autism spectrum disorders (ASDs) which is also commonly observed in Prader-Willi syndrome (PWS). RRB frequently dominates daily activities of affected individuals, interferes with opportunities to develop functional behaviors, and requires intervention and treatment. Despite functional significance of RRB, little is known about the underlying genetic mechanism. This study will identify genetic factors for restricted repetitive behavior (RRB) in ASDs and PWS. Positive results from this study should provide valuable insights into pathogenesis and novel treatment of RRB among individuals with these chronic and devastating clinical conditions.