Familial genetic risk for posttraumatic stress disorder: Associations with clinical features.

In the present study, the novel family genetic risk score (FGRS) method, a reliable quantification of latent genetic risk, was applied to posttraumatic stress disorder (PTSD) to examine associations between genetic liability and clinical features of PTSD among 3,097,180 individuals in the Swedish national registries. FGRS was calculated based on lifetime PTSD status for first- through fifth-degree relatives and examined both in PTSD cases with any lifetime registration (PTSD total) and in cases with more than one registration (recurrent PTSD) in relation to sex, age at onset (AAO), recurrence, mode of ascertainment (inpatient [IP], outpatient specialty care [SC], primary care [PC]), and comorbidities. Sex differences were not found for recurrent PTSD, but for PTSD total, female registrants had a lower FGRS value compared to male registrants, M = -.017, 95% CI of difference [-.029-.005]. Higher FGRS was found at earlier AAO for PTSD total and recurrent PTSD, ps < .001, and scores were higher among individuals with comorbidities, ps < .001. Higher FGRS was related to the number of PTSD recurrences among both total PTSD and recurrent PTSD, ps < .001 (linear effect). For both PTSD types, FGRS scores were as follows: PC < SC < IP, ps < .001. The findings indicate that genetic risk for PTSD is associated with several clinical features of the disorder, which should be included in future studies of genetic risk for PTSD. Continued investigation of these clinical features in epidemiological and molecular genetic studies of PTSD is warranted to further validate the findings.