The present study provides further evidence, suggesting a possible role for allelic variation of the PER2 gene in alcohol drinking in humans. In agreement with previous exploratory findings by Spanagel et al. [11], this study indicates that carriers of the G allele of a PER2 haplotype tagging single nucleotide polymorphism (SNP rs56013859) were less engaged in alcohol drinking than individuals homozygous for the A allele. As the G allele is the minor allele of this polymorphism, this finding can be interpreted as a protective effect of the G allele on the susceptibility to alcohol abuse. While Spanagel et al. observed an association of this SNP with high vs. low alcohol intake in a group of alcohol-dependent patients, this study confirmed the association in young adults from a high-risk community sample.
