The Army STARRS cohort (11,235 participants of genetically-confirmed European descent; see Study Populations) was investigated to replicate the Yale–Penn finding on chromosome 16 (i.e., rs8052287). Due to the unavailability of information about multiple SDs among the participants, we tested the gene interaction of SUDcombined (i.e., a single composite variable combining substance use disorders for alcohol and/or drugs) with respect to SI. This analysis was conducted using the interaction test available in PLINK 1.919, which compares the difference between SI regression coefficients in subjects with SUDcombined vs. those without SUDcombined. Age, sex, and the top 10 PCs were entered as covariates.
