Ethical approvals were obtained from the Institutional Review Board (IRB) at the Icahn School of Medicine at Mount Sinai, New York, NY, and the Regional Ethical Review Board in Stockholm. We used Swedish OCD cases collected through two studies: the EGOS cohort (Epidemiology and Genetics of Obsessive-compulsive disorder and chronic tic disorders in Sweden) (21) and the NORDiC cohort (Nordic OCD and Related Disorders Consortium) (22).
