This method calculates the sum of individual SNP associates to generate a test statistic for the gene that accounts for LD and the number of SNPs with a given gene.17 No other method identified associations between any genes and PTSD after multiple test correction, but it is interesting to note that four of the five gene-based approaches used, including GWiS (P=1.47 × 10−5), BIMBAM (P=2.04 × 10−5) and Gates (P=2.16 × 10−5), identified NLGN1 as the gene most associated with PTSD (Table 1). Here, NLGN1 is linked to post-traumatic stress disorder.