With longitudinal EHR data from the Million Veteran Program (MVP) linked to genetic data, we used two population-specific polymorphisms in ADH1B that are associated strongly with AUD in African Americans (AAs) and European Americans (EAs): rs2066702 (Arg369Cys, AAs) and rs1229984 (rs1229984" genes_norm="125">Arg48His, EAs) as criterion measures.
Specifically, the ADH1B*3 allele is present almost exclusively in Black populations and has been protective against alcohol use and alcohol use disorder.
However, the suppressive effects of inactive ALDH2 and highly active ADH1B for AUDs are only partial and interact with other factors, such as personality traits, psychiatric comorbidities, and environmental factors.
Therefore, among those at risk for greater consumption, e.g. those who experienced childhood adversity, ADH1B-rs1229984 appears to have a stronger effect on alcohol consumption and consequently on risk for AUD symptom severity.
The functional variant rs1229984 in alcohol dehydrogenase 1B (ADH1B) has been associated at a genome-wide level with alcohol use disorders in diverse adult populations.
This study examined the joint effects of variation in ADH1B and childhood adversity-a well-documented risk factor for alcohol problems and moderator of genetic liability to psychiatric outcomes-on maximum drinks consumed in a 24-hour period (maxdrinks) and alcohol use disorder (AUD) symptoms.
Two genes that encode enzymes of alcohol metabolism have the strongest effect on AUD: aldehyde dehydrogenase 2 and alcohol dehydrogenase 1B each has strongly protective variants that reduce risk, with odds ratios approximately 0.2-0.4.
For example, among those without protective alleles for ADH1B or ADH1C, OR for AUD was 1.87 as compared to those without the protective allele for ADH1B only and was 3.16 as compared to those with protective alleles for both ADH1B and ADH1C.
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.
This study examined additive and interactive effects of ALDH2 and ADH1B genotypes on drinking behavior in a mixed-gender sample of Asian young adults, focusing on continuous phenotypes (e.g., heavy episodic and hazardous drinking, alcohol sensitivity, drinking consequences) whose expression is expected to precede the onset of alcohol use disorders.
These findings suggest that studies searching for genes relating to the LR to alcohol as a vulnerability factor for AUDs should consider controlling for ADH1B genotype, as the ADH1B*2 allele could obscure the impact of other genetic polymorphisms.
These findings are consistent with the hypothesis that enhanced sensitivity to alcohol and lower levels of alcohol use reflect the mechanism by which ADH1B*2 protects against developing an AUD.
However, multivariate analyses under a hierarchically well-formulated model strategy with interaction and confounding assessment indicated that (i) heavy alcohol intake was a significant risk factor (odds ratio per 1.0 g of daily ethanol intake; 1.096, 95% confidence interval; 1.026-1.171) for developing AUD after adjusting for other confounders; and (ii) ADH2*1/1 genotype and ALDH2*1/1 genotype were not risk factors after adjusting for daily ethanol intake and other confounders.
The present findings suggest that one of the genetic factors that may be related to probable AUD among Thai males living in the north-east is the ADH2 gene.
Because family history of alcoholism is one of the best predictors of the development of alcohol use disorders, this pilot study suggests that, in this sample of African American young adults, the ADH2*3 allele may be associated with a lowered risk for the development of alcoholism.
ADH2*2, however, was not related to alcohol use disorders, alcohol-induced flushing and associated symptoms, number of binge drinking episodes in the past 90 days, maximum number of drinks ever consumed, or self-reported levels of response to alcohol.
Among the Atayal, the group with alcohol use disorders (alcohol dependence and alcohol abuse) had a significantly lower frequency of the ADH2*2 allele (0.82) than those without alcohol use disorders (0.91).