There are numerous limitations apparent on review of the above literature, both in terms of quality and quantity of studies. The primary weakness is the direct lack of any replicated finding thus far for any pattern of alcohol use. However, promisingly, recently the top markers for alcohol consumption from Philibert (2014) have been shown to demonstrate the classic “U-shaped” curve effect on survival in a large community sample (n = 656) [109]. In general, candidate gene associations have not replicated well in array-based studies, although this may be in part due to lack of coverage. The literature using 27k data is unfortunately limited by lack of reporting of full findings and methods. Among the two more well-powered studies using Illumina’s 450k array, one used a non-primary source of DNA [99], transformed lymphoblasts, and suffered from potential weakness in characterizing alcohol use patterns (self-report over the last 6 months). The second study [101] addressed those issues and found a much larger number of associations, suggesting that some of these findings, if replicated, could point toward the development of clinical epigenetic biomarkers.
