Because inactive ALDH2 is an established negative risk factor for alcoholism, alcoholics with the mutant allele, ALDH2*2, were considered a relatively homogeneous group.
Non-coding variations in GABRA2, the gene encoding the alpha2 subunit, are associated with the risk for alcoholism, suggesting that regulatory differences are important.
The ADH1C*2 allele was significantly associated with alcohol dependence overall and within Indo-TT ancestry, however, it was not associated with current or heaviest alcohol consumption levels.
The alcoholics had significantly lower frequencies of the ADH2*2, ADH3*1, and ALDH2*2 alleles than did the nonalcoholics, suggesting that genetic variation in both ADH and ALDH, by modulating the rate of metabolism of ethanol and acetaldehyde, influences drinking behavior and the risk of developing alcoholism.
The key findings of the earlier studies were that variations (i.e., polymorphisms) in the DNA sequences of the genes encoding alcohol dehydrogenase 1B (i.e., the ADH1B gene), aldehyde dehydrogenase 2 (i.e., the ALDH2 gene), and other alcohol-metabolizing enzymes mediate the risk for alcoholism; moreover, these polymorphisms also have an impact on the risk of alcohol-related cancers, such as esophageal cancer.
The low sensitivity in the present study suggests that a lack of alcohol flushing may play a crucial role in the development of alcohol dependence in women with inactive ALDH2.
The alcoholism-susceptibility genotype ADH1B*1/*1 was less frequent in the gastrectomy group, suggesting a competitive gene-gastrectomy interaction for alcoholism.
The ALDH2*2 variant is associated with partial protection against alcohol dependence but confers significantly increased risk for alcohol-related cancers as a function of alcohol exposure.
We investigated whether variation in genes encoding cytochrome P450 2E1 (CYP2E1) or acetaldehyde-metabolising enzymes (ALDH1A1, ALDH2) might alter the risk of AD, with and without symptoms of anxiety, in a Cape population with mixed ancestry.
The frequencies of the alleles ADH(2)2 and ADH(3)1, coding for the high-Vmax beta 2- and gamma 1-ADH respectively, and of the mutant ALDH(2)2 in the Oriental subjects with alcoholism or alcoholic cirrhosis are significantly lower than those in healthy controls.
The present meta-analysis underscores significant associations of ADH2*1, ADH3*2, and ALDH2*1 alleles and the risk of alcoholism (OR = 1.89 [95% CI 1.56-2.28], 1.32 [95% CI 1.12-1.57], and 4.35 [95% CI 3.04-6.23], respectively).
The current study examined the influence of gender, negative and positive daily life events, and GABRA2 genotype (SNP rs279871) on alcohol dependence, testing two- and three-way interactions between these variables using multi-level regression models fit to data from 2,281 White participants in the Collaborative Study on the Genetics of Alcoholism.
The GABRA2 locus has been found to be associated with alcohol dependence in several studies, but no functional variant that can account for this association has been identified.
Significant associations were also observed between ADS risk and the ADH1B/1C intergenic variant, rs1789891 [allelic P = 7.2 × 10(-5) , OR = 1.4 (1.2, 1.6)] and three non-synonymous SNPs rs698, rs1693482 and rs283413 in ADH1C.
We conclude that genetic variation at or near the GABRA2 locus significantly affects vulnerability not only to AD, but to other forms of substance use including ND and CD, and that the effects may be sex dependent.
The attributable fraction of those genetic factors, calculated based on population controls, indicates that alcoholism in 86.5% of alcoholic patients can be attributed to the detrimental effect of ADH1B*47Arg and/or ALDH2*487Glu in Korean population.
Genetic polymorphisms of alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) affect susceptibility to alcoholism and may affect body weight via gene-associated differences in fuel utilization in alcoholics.
Genetic association studies of diverse ethnic groups have firmly demonstrated that the allelic variant ADH1B*2 significantly protects against alcoholism but that ADH1C*1, which is in linkage with ADH1B*2, produces a negligible protection.
The results revealed that (1) the less active allele of the ADH2 gene (ADH2*1) is associated with an increased risk for alcohol dependence, alcohol-induced persistent amnestic disorder, alcohol withdrawal syndrome, and cancer of the upper GI tract; (2) the inactive allele of the ALDH2 gene (ALDH2*2) is associated with a decreased risk for alcohol dependence, and an increased risk for alcoholic polyneuropathy and cancer in the same region; and (3) these genetic variations modify clinical features of alcohol dependence.