To determine if common variants in the OPRM1 promoter region may be contributing to our findings, we resequenced DNA from a subset of our cohort. One hundred and fortyeight subjects (47 African-American, 51 Hispanic, and 50 Caucasian) were resequenced across the OPRM1 promoter region, which contained the 16 CpG sites we examined above. The allele frequency of rs17174638 was 0.09 in African-Americans. This variant was not found in the Hispanics or Caucasians. Variant rs9282815 was found with an allele frequency of 0.02 in both the African-American and the Hispanic subjects, and was absent in the Caucasian subjects. Variant rs1799972 (C17T), which substitutes a valine for an alanine at amino acid 6, was found with an allele frequency of 0.22 in the African-Americans, 0.04 in the Hispanics, and 0.01 in the Caucasians. None of the variants we identified in the OPRM1 promoter region alters any of the CpG sites that we have studied above.
