To date, only three small published studies have analyzed DNA methylation changes in postmortem brains of AUD subjects (Table 4). Taqi et al.46 examined methylation levels of CpGs in the PDYN in postmortem PFC of 14 AUD patients and 14 control subjects. They reported altered methylation of three SNP-CpGs in postmortem PFC of AUD subjects. Another study examined global methylation alterations in postmortem frontal cortex of AUD subjects, but no significant findings were obtained.40 The most recent study from our lab examined DNA methylomic alterations in postmortem PFC of 16 pairs of male and 7 pairs of female AUD and control subjects (46 subjects in total).41 We identified 1,812 CpGs (in 1,099 genes) that were differentially methylated in male AUD subjects. The genes carrying these differentially methylated CpGs are involved preferentially in neural development and transcriptional regulation. Although, these postmortem brain epigenetic studies have generated interesting findings, they are limited by the small sizes of brain tissue samples and the unavailability of tissues from multiple reward-related brain regions. These limitations will be overcome with the increased access of a larger
