Increased global DNA methylation has been found in lymphocytes of alcoholics (Bleich et al. 2006; Bonsch et al. 2004, 2006). Altered DNA methylation at specific CpG sites has been shown to alter the expression of various genes (e.g. Iguchi-Ariga and Schaffner 1989; Zhang et al. 2010). In our cohort, we found point-wise significant decreases in DNA methylation in the Hispanic, but not the African-American, severe former heroin addicts with a history of alcoholism at the −93 and the −60 CpG sites. However, these differences were not significant after adjusting for multiple testing.
