drugs. We identified 481 dependent and 1053 control unrelated European-American and 516 dependent and 409 control unrelated African-American subjects for this analysis. Genotyping for these samples was performed using Illumina 1M SNP arrays at the Center for Inherited Disease Research (CIDR), with quality controls and principal components analysis (PCA) controls for racial/ethnic background available at the CIDR website (www.cidr.jhmi.edu). Genotypes from dependent and control individuals were selected from dbGAP files. p values for each SNP were based on χ2 tests. The resulting p values were then analyzed and compared to the results from the NIDA individuals by the “cluster then converge” method described above.
