The OPRM1 genotyping was successful with 100% of the genotypes being completed in 265 individuals with 61 individuals having at least one asp40 allele, for an asp40 carrier rate of 23% which is consistent with Hapmap data for European Caucasians and exactly the rate reported for treatment-seeking alcoholics in the COMBINE Study (Anton et al., 2008). Genotype frequency did not deviate from HWE (X2(2)=2.14, p=.344). Forty-three of the asp40 carriers met further inclusion/exclusion criteria and were randomized to naltrexone (n=19) or placebo (n=24) while 40 individuals with an asn40asn genotype who were closely matched to the asp40 individuals were also randomized to naltrexone (n=19) or placebo (n=21).
