Our previous case-control study in a Tibetan population noted that the positive association between c2 allele of cytochrome P4502E1 (CYP2E1) gene and AUD might only exist in males who are homozygotes for 1 alleles of aldehyde dehydrogenase-2 (ALDH2) and alcohol dehydrogenase-1B (ADH1B) genes, but this interaction did not reach statistical significance.