To perform case-control association analyses, the allele frequencies from the NHLBI-ESP were used to represent a control population. The allelic association of SNPs with opioid and cocaine addiction was determined using the Fisher’s exact test. Due to the different minor allele frequencies of the polymorphisms in EA and AA populations, the two populations were analyzed separately. Heroin and cocaine addicts were combined and analyzed as a ‘drug addicted’ cohort. The false discovery rate (FDR) correction was used to adjust for multiple testing for p-values in each ethnicity separately [6].
