To facilitate the third aim, DNA from cheek swabs was collected and extracted following published procedures [22,47,48]. The CNR1 rs2023239 and FAAH rs324420 SNPs were genotyped using 5′-nuclease assays (TaqMan®, Foster City, CA, USA) purchased from ABI in conjunction with the ABI 7500 thermocycler [49]. To ensure accurate genotyping results, accuracy was assessed by re-genotyping 25% of the total sample at random for both SNPs, and was found to be 100% accurate.
