The PLINK 1.07 genetic association analysis program33 was used to verify SNP data quality, test for departure from Hardy-Weinberg equilibrium, test individual SNPs for statistical association, perform multiple correction testing (Bonferroni), and analyze pairwise combinations of SNPs. General linear stepwise regression analysis was used to evaluate genotype group differences with covariates: e.g., age, sex, postmortem interval, brain pH, and toxicology. Post-hoc analysis regarding genotype was performed by using Fisher’s least-squares difference test. Significance was set at P<0.05 and trends considered for P<0.10. Statistical evaluations were carried out using JMP (SAS Institute, Cary, NC) software package.
