We searched for chromosomal regions that contained at least three variants associated with heroin addiction that were in close proximity with each other. Variants were sorted by ascending P value in each ethnic group (Caucasian and African American) and the 500 variants with the smallest P value (point-wise P ≤ 0.0037 in the Caucasians and P ≤ 0.0238 in the African Americans) were evaluated to determine if any set of at least three variants were within 100,000 nucleotides of each other (Table 4, point-wise P ≤ 0.0020 for Caucasians and point-wise P ≤ 0.0079 for African Americans). In Caucasians, three variants from this list, spanning 14,000 nucleotides, are found in an intron of the regulating synaptic membrane exocytosis protein 2 gene RIMS2. The cardiomyopathy associated 3 gene CMYA3 in African Americans has three variants in a single intron that spans 3,000 nucleotides; another set of three variants are located at chromosome 13q13.1, spanning a 9,000 nucleotide region with no known function.
