Genotypes of alcohol dehydrogenase and aldehyde dehydrogenase loci in Japanese alcohol flushers and nonflushers

Summary A much higher incidence of alcohol flushing among Orientals in comparison to Caucasians, i.e., >50% vs 5%–10%, has been attributed to racial differences in alcohol-metabolizing enzymes. A large majority of Orientals are atypical in alcohol dehydrogenase-2 locus (ADH₂), and their livers exhibit significantly higher ADH activity than the livers of most Caucasians. Approximately 50% of Orientals lack the mitochondrial aldehyde dehydrogenase (ALDH₂) activity, and elimination of acetaldehyde might be disturbed. We determined by means of hybridization of genomic DNA samples with allele specific oligonucleotide probes, genotypes of the ADH₂and ALDH₂loci in Japanese alcohol flushers and nonflushers. We found that all individuals with homozygous atypical ALDH₂²/ALDH₂²and most of those with heterozygous atypical ALDH₁²/ALDH₂²were alcohol flushers, while all subjects with homozygous usual ALDH₁²/ALDH₁²were nonflushers. Frequency of the atypical ADH₂²was found to be higher in alcohol flushers than in nonflushers, but the statistical significance was not established in the sample size examined.