We estimated the magnitude of the contributions of different molecular mechanisms to the effects of addiction susceptibility. We compared observed values to those that would be obtained by chance based on 10,000 Monte Carlo simulations (See Methods for details). The categories of 'synonymous SNP' (p = 0.001) and 'non-synonymous SNP' (p = 0.001) showed nominally significant over-representation, consistent with the conventional idea that SNPs in coding regions may play important roles in disease susceptibility. In addition, the data suggest regulatory SNPs that modify transcription factor, microRNA binding or alternative splicing sites, may also contribute to addiction susceptibility in addition to those played by non-synonymous SNPs and other allelic variants.
