Investigation of polygenic risk scores and subphenotypes in social anxiety disorder.

Social anxiety disorder (SAD) is a common anxiety disorder (ANX) with moderate heritability that often co-occurs with other mental disorders. Until now, sample sizes in genetic analyses of SAD have been limited, so that the genetic basis of SAD and its subphenotypes is still largely unknown. In a large cohort comprising n = 1,194 SAD patients derived from five German cohorts and n = 3,409 controls from the Heinz Nixdorf Recall Study, we computed polygenic risk scores (PRS) at six p-thresholds using PRSice-2 based on large-scale genome-wide association studies for depression, major depressive disorder (MDD), ANX, schizophrenia (SCZ), bipolar disorder (BD), attention-deficit/hyperactivity disorder (ADHD), anorexia nervosa (AN), autism spectrum disorder (ASD), and alcohol dependence (AD). We used general linear models to examine the association between the PRS and SAD status. In SAD subsamples, we investigated whether the PRS are associated with SAD subphenotypes (i.e., SAD severity, current depressive symptoms, comorbid MDD) using correlation analyses and a general linear model. Results were corrected for multiple testing. The SAD status was significantly associated with PRS for depression, MDD, ANX, SCZ, BD, AN, and ASD (pBH-adjusted<0.05), but not with PRS for ADHD and AD. In SAD subsamples, the subphenotype analyses revealed no significant associations after correction for multiple testing (pBH-adjusted>0.05). Our results support that SAD seems to be genetically highly overlapping with other mental disorders, which might underline a common psychopathological factor. No significant association was found with SAD severity, current depressive symptoms or comorbid MDD. A better understanding of the genetic architecture of SAD may help to develop new diagnostic and treatment approaches.