Posttraumatic Stress Disorder (PTSD) among adolescents exposed to disasters is prevalent and increases health morbidity and mortality. Although PTSD is common among youth exposed to traumatic stressors, is not present among all exposed youth. Disaster-exposed youth, in comparison to adults, are at significantly greater risk for PTSD, with symptoms often persisting for many months and years post-disaster;however, youth are drastically under-represented in post-disaster studies. Considerable effort, primarily in the adult literature, has been given to identify variables related to PTSD risk, but only about 20 percent of variance has been explained by psychosocial variables;thus, there has been interest in including genetic determinants into studies of PTSD. Despite moderate heritability estimates (30 percent) for PTSD, modern studies of genetic risk factors for PTSD are relatively few in number and psychiatric genetic investigations have been mixed in their ability to identify direct effects of genotypes on disorder phenotypes. Notably, there are no existant genetically informed studies of adolescent PTSD, a critical developmental phase. Therefore, the need is high for novel approaches to examining genetic and environmental moderators to inform models of risk and resilience in disaster exposed youth. Therefore, we are responding to Notice Number (NOT-OD-10-032) Title: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications (R01, R03, R15, R21, R21/R33, and R37) through the NIH Basic Behavioral and Social Science Opportunity Network (OppNet). The primary objective of this project, directly in accordance with the research priorities of the NIH OppNet (NOT-OD-10- 032), is to add genetic sampling to a funded R01 investigation of disaster-exposed youth. The parent project will recruit a population-based sample of 3,000 disaster exposed youth and their parents participating in an NIH-funded longitudinal, web-based intervention study (R01MH081056). Youth and parent participants will complete an initial phone-based assessment, where information regarding disaster exposure, other traumatic event experiences and incident characteristics, family-related variables, and PTSD and other mental health symptomatology will be gathered. OppNet funding will be used to expand the interview to include a larger range of possible environmental modifiers. During the baseline interview, adolescents will be asked to provide saliva samples for DNA analysis, which will also be conducted through use of OppNet funding. Participants will be sent a collection kit that they return via U.S. mail, methods we have successfully executed in a previous disaster-focused study. DNA will be extracted from saliva samples and candidate genes will be examined via the tagging SNP method and by assying specific variable number tandem repeats of genes reported in the extant literature to be relevant for PTSD. By examining GxE interactions this project will assess whether relations between candidate genes and PTSD are moderated by aspects of the environment. This project, by harnessing the behavioral and social data from the R01 with the biologic data from the OppNet funding, will afford a deeper understanding of the interplay between the environment and biology in the aftermath of a traumatic stressor. Additionally, this project has potential public health benefits of informing the knowledge of pathophysiology of PTSD which may lead to improved pharmacologic treatment targets. PUBLIC HEALTH RELEVANCE: Many youth are exposed to disasters and other potentially traumatic events that can produce posttraumatic stress disorder (PTSD);however, not all exposed individuals develop PTSD, so information is needed about how biologic and environmental factors interact to increase or decrease risk of PTSD post-disaster. This project addresses this issue by collecting DNA from adolescents who were exposed to a disaster, allowing for examination of gene by environment interactions for adolescent PTSD. By testing whether relevant candidate genes and features of the environment modify the impact of exposure to traumatic events, we will advance basic science knowledge that will deepen our understanding of the causes of pediatric PTSD, which may inform secondary prevention or intervention of PTSD in youth.