Specific genetic variants have been linked to variation in alcohol consumption, the most influential being rs671 in the aldehyde dehydrogenase (ALDH2) gene and a cluster of variants spanning the alcohol dehydrogenase genes (ADH1B, ADH1C, ADH5, ADH6, ADH7) located on chromosome 4q23. The catalytically inactive version of ALDH2 encoded by the A allele of rs671 leads to slower metabolism of acetaldehyde that causes the alcohol flush reaction. This reaction causes alcohol to be aversive for the A carriers of rs671.6, 7 As such, this polymorphism is highly protective against alcoholism in Asian populations,8 although it has limited impact in European and African populations where it is often monomorphic.9 The rs1229984 in ADH1B is also associated with an alcohol-flush reaction in Asian populations and thus protects against high alcohol consumption.10 It is also found to associate with drinking pattern phenotypes in European and African populations where the minor allele frequency (MAF) is ~1–4%.9, 11, 12 Common SNPs in ADH7 have been associated with alcohol consumption in an Australian cohort of twins.13
