As an alternative approach to SNP-based association analysis, we tested the joint association of markers within genes using a gene-based association analysis in MAGMA31, which is a 2-stage method that first maps SNPs to genes and then tests whether a gene is significantly associated with PTSD. The gene-based analysis identified 175 GWS genes (Supplementary Table 13 and Supplementary Fig. 7). Of these, 52 were distinct from the genes implicated by the gene-mapping of individual SNPs within GWS loci. These notably include DRD2, which has been thoroughly investigated in the context of psychiatric disorders and is a significant GWAS locus for multiple psychiatric disorders including schizophrenia32 (see Supplementary Note and Supplementary Table 14 for further investigation of conditionally independent SNPs within these 52 genes).
