A further analysis of the ADH1B locus also highlighted that non-coding variants contribute to AD risk and the gene haplotype structure to population differences [Polimanti and others 2015a]. GWAS conducted in Asian populations also confirmed the protective role of ALDH2 rs671 [Baik and others 2011; Quillen and others 2014; Takeuchi and others 2011]. Recent studies also reported that ADH1B rs1229984 and rs2066702 are associated directly with the accumulation of blood acetaldehyde [Kang and others 2014] as predicted by knowledge of their physiological functions, in agreement with their effects on enzymatic activities [Chiang and others 2016] and the results of genetic studies of alcoholism. However, ALDH2 rs671, rather than ADH1B rs1229984, seems more responsible for acetaldehyde concentrations and facial flushing in Asians populations [Peng and others 2014]. In this scenario, where genotype affects the enzymatic activity which increases the symptoms which reduce alcohol drinking behaviors, other factors also seem to moderate the protective effect of ADH1B rs1229984 on alcohol drinking behaviors. Two studies conducted in independent samples observed a reduced protective effect of ADH1B rs1229984 on alcohol drinking behaviors in subjects
