Polymorphism of alcohol dehydrogenase genes in alcoholic and nonalcoholic individuals from Valencia (Spain)

Association of alcohol dehydrogenase 1C gene *1/*2 polymorphism with alcohol Dependence(AD) in Turkey: A meta-analysis

Previous studies have investigated the association between ADH1C ^*1/^*2 polymorphism and alcohol dependence (AD), but have yielded controversial results in Turkey. Therefore, in an effort to illustrate whether ADH1C ^*1/^*2 polymorphism is associated with AD risk in Turkish population, we used meta analysis to synthetically evaluate the effect of ADH1C ^*1/^*2 polymorphism on AD. Publications were identified by searching in PubMed and EMBASE databases. Four eligible studies involving 400 controls and 421 cases were included in this study. Overall, there is a significant association between ADH1C ^*1/^*2 polymorphism and AD risk in the allelic model (OR = 1.66, 95% CI = 1.05-2.62, P = 0.03) and recessive model (OR = 1.72, 95% CI = 1.14-2.58, P = 0.01), while no significance was discovered in the dominant genetic model, homozygote model and heterozygotemodel. No publication bias was indicated from Begg's and Egger's test. Our meta-analysis results suggested that a potential relationship between ADH1C ^*1/^*2 polymorphism and AD risk in Turkish population. Further studies are confirmed to resolve this question about the etiological mechanisms of the correlation.

Association between ADH1C and ALDH2 polymorphisms and alcoholism in a Turkish sample

BACKGROUND

Polymorphisms in the genes encoding alcohol metabolizing enzymes are associated with alcohol dependence.

AIM

To evaluate the association between the alcohol dehydrogenase 1C (ADH1C) Ile350Val and aldehyde dehydrogenase 2 (ALDH2) Glu504Lys polymorphisms and alcohol dependence in a Turkish sample.

METHODS

235 individuals (115 alcohol-dependent patients and 120 controls) were genotyped for ADH1C and ALDH2 with PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism). Association between the polymorphisms and family history, daily and maximum amount of alcohol consumed was investigated. The associations between alcohol dependence, severity of consumption and family history and the polymorphisms were analyzed by chi-square or Fisher's exact test where necessary. Relationship between genotypes and dependence related features was evaluated using analysis of variance (ANOVA).

RESULTS

The -350Val allele for ADH1C (ADH1C*2) was increased in alcohol-dependent patients (P = 0.05). In individuals with a positive family history, the genotype distribution differed significantly (P = 0.031) and more patients carried the Val allele compared with controls (P = 0.025). Genotyping of 162 participants did not reveal the -504Lys allele in ALDH2.

CONCLUSIONS

These findings suggest that ADH1C*2 is associated with alcohol dependence in the Turkish population displaying a dominant inheritance model. ADH1C*2 allele may contribute to the variance in heritability of alcohol dependence. The ALDH2 -504Lys/Lys or Glu/Lys genotypes were not present in alcohol-dependent patients, similar to that seen in European populations and in contrast to the findings in the Asian populations.

Further clarification of the contribution of the ADH1C gene to vulnerability of alcoholism and selected liver diseases

The alcohol dehydrogenase 1C (ADH1C) subunit is an important member of the alcohol dehydrogenase family, a set of genes that plays a major role in the catabolism of ethanol. Numerous association studies have provided compelling evidence that ADH1C gene variation (formerly ADH3) is associated with altered genetic susceptibility to alcoholism and alcohol-related liver disease, cirrhosis, or pancreatitis. However, the results have been inconsistent, partially, because each study involved a limited number of subjects, and some were underpowered. Using cumulative data over the past two decades, this meta-analysis (6,796 cases and 6,938 controls) considered samples of Asian, European, African, and Native American origins to examine whether the aggregate genotype provide statistically significant evidence of association. The results showed strong evidence of association between ADH1C Ile350Val (rs698, formerly ADH1C *1/*2) and alcohol dependence (AD) and abuse in the combined studies. The overall allelic (Val vs. Ile or *2 vs. *1) P value was 1 × 10(-8) and odds ratio (OR) was 1.51 (1.31, 1.73). The Asian populations produced stronger evidence of association with an allelic P value of 4 × 10(-33) [OR 2.14 (1.89, 2.43)] with no evidence of heterogeneity, and the dominant and recessive models revealed even stronger effect sizes. The strong evidence remained when stricter criteria and sub-group analyses were applied, while Asians always showed stronger associations than other populations. Our findings support that ADH1C Ile may lower the risk of AD and alcohol abuse as well as alcohol-related cirrhosis in pooled populations, with the strongest and most consistent effects in Asians.

Association of a genetic polymorphism of the alcohol-metabolizing enzyme ADH1C with alcohol dependence: results of a case-control study

OBJECTIVE

Alcohol dependence causes serious problems which may be influenced by genetic factors associated with alcohol metabolism. The aim was to investigate the allelic and genotypic difference in distribution of a polymorphism in alcohol dehydrogenase 1C gene (ADH1C) between alcohol-dependent individuals and controls, and to examine if these genotypes were associated with the age at which the patient became alcohol-dependent.

METHODS

We conducted a case-control study including 90 alcohol-dependent cases and 100 historic controls. The genomic DNA was isolated and the alleles were analyzed with an RFLP.

RESULTS

The ADH1C*1 allele frequencies were 0.89 (95% CI 0.84-0.91) in controls and 0.68 (95% CI 0.61-0.74) in alcohol-dependent patients. The frequencies of the ADH1C*2 allele were 0.11 (95% CI 0.07-0.14) and 0.32 (95% CI 0.25-0.38) among controls and alcohol-dependent patients, respectively (p < 0.0001). The ADH1C*1/*1 genotype frequency was significantly higher in the control group (77%) compared to that of the alcohol-dependents (51%, p < 0.0001). The ADH1C*1/*2 genotype frequency was significantly lower in the control group (23%) compared to that of the alcohol-dependents (42%, p < 0.0001). We obtained no statistically significant difference among the ADH1C genotype groups regarding age.

CONCLUSIONS

These findings suggest that a significantly higher presence of ADH1C*2 allele is associated with alcohol dependence in a Turkish population. Studies with other related polymorphisms are needed to more precisely estimate the association of alcohol dependence with ADH1C.

Strong association of the alcohol dehydrogenase 1B gene (ADH1B) with alcohol dependence and alcohol-induced medical diseases

BACKGROUND

The alcohol dehydrogenase 1B gene (ADH1B) is hypothesized to affect predisposition to alcohol dependence (AD) and abuse. A variant of the ADH1B gene (rs1229984 or Arg48His; previously referred to as Arg [*1] and His [*1]) has been reported to be associated with reduced rates of alcohol and drug dependence. Different studies have produced inconclusive results regarding association between rs1229984 (or rs2066702) and substance dependence.

METHODS

Using the cumulative association study literature from the past 21 years from both English- and Chinese-language publications, this meta-analysis seeks to clarify the contradictory findings and to examine whether the aggregate data provide new evidence of significant association.

RESULTS

The results, based on a large sample size (9638 cases and 9517 controls), suggested strong associations with alcohol dependence and abuse as well as alcohol-induced liver diseases, with an allelic (Arg vs. His) p value being 1 × 10(-36) and odds ratio (OR) (95% confidence intervals [CI]) 2.06 (1.84-2.31) under the random effects model. The dominant and recessive models produced larger ORs of 2.17 and 3.05, respectively. When more stringent criteria and subgroup analyses were imposed, the associations remained consistent and were strongest in various Asian groups (allelic p = 7 × 10(-42) and OR (95% CI) = 2.24 [1.99-2.51] with ORs of 2.16 and 4.11 for dominant and recessive models, respectively).

CONCLUSIONS

Our findings provide further strong evidence for the involvement of the ADH1B gene in the pathogenesis of alcohol dependence and abuse as well as for some alcohol-induced medical diseases in the multiple ethnic populations--in particular, certain Asian populations.

Alcoholism and alcohol drinking habits predicted from alcohol dehydrogenase genes

Alcohol drinking habits and alcoholism are partly genetically determined. Alcohol is degraded primarily by alcohol dehydrogenase (ADH) wherein genetic variation that affects the rate of alcohol degradation is found in ADH1B and ADH1C. It is biologically plausible that these variations may be associated with alcohol drinking habits and alcoholism. By genotyping 9080 white men and women from the general population, we found that men and women with ADH1B slow vs fast alcohol degradation drank more alcohol and had a higher risk of everyday drinking, heavy drinking, excessive drinking and of alcoholism. For example, the weekly alcohol intake was 9.8 drinks (95% confidence interval (CI): 9.1-11) among men with the ADH1B.1/1 genotype compared to 7.5 drinks (95% CI: 6.4-8.7) among men with the ADH1B.1/2 genotype, and the odds ratio (OR) for heavy drinking was 3.1 (95% CI: 1.7-5.7) among men with the ADH1B.1/1 genotype compared to men with the ADH1B.1/2 genotype. Furthermore, individuals with ADH1C slow vs fast alcohol degradation had a higher risk of heavy and excessive drinking. For example, the OR for heavy drinking was 1.4 (95% CI: 1.1-1.8) among men with the ADH1C.1/2 genotype and 1.4 (95% CI: 1.0-1.9) among men with the ADH1B.2/2 genotype, compared with men with the ADH1C.1/1 genotype. Results for ADH1B and ADH1C genotypes among men and women were similar. Finally, because slow ADH1B alcohol degradation is found in more than 90% of the white population compared to less than 10% of East Asians, the population attributable risk of heavy drinking and alcoholism by ADH1B.1/1 genotype was 67 and 62% among the white population compared with 9 and 24% among the East Asian population.

Alcohol dehydrogenase and aldehyde dehydrogenase gene polymorphism in alcohol liver cirrhosis and alcohol chronic pancreatitis among Polish individuals

OBJECTIVE

To investigate the effects of ADH and ALDH gene polymorphism on the development of alcoholism, alcohol liver cirrhosis and alcohol chronic pancreatitis among Polish individuals.

MATERIAL AND METHODS

We determined the allele and genotype of ADH2, ADH3 and ALDH2 in 198 subjects: 57 with alcohol cirrhosis, 44 with alcohol chronic pancreatitis and 43 "healthy alcoholics"; 54 healthy non-drinkers served as controls. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method on white cell DNA.

RESULTS

In the population examined the ADH2*1 allele frequency was 97.97%. The tests did not show the ADH2*3 allele. The ADH3*1 allele frequency was 57.07%. The ADH2*1 and the ADH3*1 alleles were statistically more common among patients who abuse alcohol in comparison with the controls. The ADH2*2 allele was not detected in any of the patients with chronic alcohol pancreatitis. The ADH2*1/*1 and the ADH3*1/*1 genotypes were statistically significantly more common among the patients who abuse alcohol than in the control group. All patients were ALDH2*1/*1 homozygotic. Patients with the ADH3*1 allele and the ADH3*1/*1 genotype started to abuse alcohol significantly earlier in comparison to the patients with the ADH3*2 allele and the ADH3*2 /*2 genotype.

CONCLUSIONS

In the Polish population examined, the ADH3*1 allele and the ADH3*1/*1 genotype are conducive to the development of alcoholism, alcohol liver cirrhosis and alcohol chronic pancreatitis. However, the ADH2*2 allele is likely to protect against these conditions. Genetic polymorphism of ALDH2 shows no correlation with alcohol addiction or alcohol cirrhosis and alcohol chronic pancreatitis. The ADH3*1 allele and the ADH3*1/*1 genotype are conducive to alcohol abuse starting at a younger age.

Genetic associations of alcohol and aldehyde dehydrogenase with alcohol dependence and their mechanisms of action

Two alcohol dehydrogenase genes (ADHIB and ADH1C on chromosome 4) and one aldehyde dehydrogenase gene (ALDH2 on chromosome 12) exhibit functional polymorphisms that are associated with lower rates of alcohol dependence. The ALDH2*2 allele,found almost exclusively in Asian populations, has the strongest relationship. The ADH1B*2, ADH1B*3, and ADHlC*i alleles, found in varying prevalence in different ethnic groups, have also been associated with lower rates of alcohol dependence. Studies of the ADHIBand ADH1C haplotypes, however, have shown that ADH1C*I is in linkage disequilibrium with ADHiB*2, and the ADH1C*i allele does not appear to have significant unique associations with alcohol dependence. The hypothesized mechanism underlying the associations of the ADH1B and ALDH2 polymorphisms with alcohol dependence is that the isoenzymes encoded by these alleles lead to an accumulation of acetaldehyde during alcohol metabolism. Based on their kinetic properties, ALDH2 *2 theoretically should lead to a slower removal of acetaldehyde than ALDH2*1, whereas ADH1B*2 and ADH1B*3 should lead to a more rapid production of acetaldehyde than ADHIB*I. It is further hypothesized that elevations in acetaldehyde cause more intense reactions to alcohol and lead to lower levels of alcohol intake. Data are consistent with the hypothesis that elevations in acetaldehyde, increased sensitivity to alcohol, and lower levels of drinking reflect the mechanism by which the ALDH2*2 allele reduces risk for alcohol dependence. There is also some evidence supporting this mechanism for the ADH1B*2 and ADHIB*3 alleles, but the results are less consistent. These findings highlight the value of trying to elucidate the mechanism by which genes ultimately give rise to differences in alcohol dependence through the examination of mediating behaviors.

Do alcohol-metabolizing enzyme gene polymorphisms increase the risk of alcoholism and alcoholic liver disease?

Case-control studies that have investigated the association between alcoholism and alcohol-induced liver damage and the ADH2, ADH3, CYP2E1, and ADLH2 polymorphisms have reported controversial or inconclusive results. Thus, we conducted a meta-analysis of 50 association studies of the above polymorphisms. We explored potential sources of heterogeneity and bias, performed subgroup analyses by racial background and sex, performed sensitivity analyses for studies not in Hardy-Weinberg equilibrium, and performed a subgroup analysis for cases that met strict criteria for alcoholism. 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 subsequent subgroup analyses showed association for ADH2*1 and ADH3*2 only in East Asians (OR = 2.23 [95% CI 1.81-2.74] and 1.91 [95% CI 1.45-2.53], respectively) and East Asian males (OR = 2.21 [95% CI 1.57-3.10], 1.69 [95% CI 1.10-2.59], respectively). In East Asian males, the OR for ALDH2*1 was 3.66 (95% CI 1.68-7.96). In Caucasians, sensitivity analysis revealed an association for ADH2*1 in alcoholism (OR = 1.62 [95% CI 1.22-1.89]). When strict criteria were imposed, the pattern of results remained unaltered. For liver disease, there were no significant associations for ADH2*1, ADH3*2, or ALDH2*1 in all subpopulations. The CYP2E1 polymorphism showed no association whatsoever. There is evidence that alleles are mainly dominant. In conclusion, there was heterogeneity between studies in alcoholism for ADH2, ADH3, and ALDH2, and lack of bias in all polymorphisms. The above findings reinforce the need for more rigorous studies, and for regular synthesis of studies' results.

Genetic associations of alcohol dehydrogenase with alcohol use disorders and endophenotypes in white college students

Associations of alcohol dehydrogenase (ADH) gene polymorphisms (ADH1B*2 and ADH1C*1) with a lifetime alcohol use disorder (AUD) were examined in White college students. Alcohol-related endophenotypes likely to be influenced by elevations in acetaldehyde were also assessed. Individuals with an ADH1B*2 allele had lower rates of AUDs, consumed a lower maximum number of drinks in a 24-hr period, reported a greater level of response to alcohol, were more likely to have experienced alcohol-induced headaches following 1 or 2 drinks, and reported more severe hangovers than those lacking this allele. 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.

Scanning of genetic effects of alcohol metabolism gene (ADH1BandADH1C) polymorphisms on the risk of alcoholism

Alcoholism is a multifactorial and polygenic disorder involving complex gene-to-gene and gene-to-environment interactions. Alcohol metabolism is one of the biological determinants that could significantly be influenced by genetic polymorphisms in alcohol-metabolism genes. These genetic polymorphisms are believed to influence drinking behavior and development of alcoholism. Direct DNA sequencing of whole ADH1B and ADH1C genes revealed 36 sequence variants, including six nonsynonymous and 14 novel polymorphisms. Seventeen polymorphisms among them were selected for genotyping in a larger study (n = 352) based on linkage disequilibria (LDs) among SNPs, locations, and frequencies. Hardy-Weinberg equilibrium (HWE) analyses of polymorphisms revealed severe deviations only in alcoholics, which strongly suggest that a selection bias (or pressure) may be involved. The analyses of genotype distribution in alcoholics (n = 106) and normal controls (n = 246) showed dramatic associations with the risk of alcoholism. Fourteen polymorphisms in ADH1C and ADH1B showed a series of different strengths of association and magnitudes of risk. Based on referent and subgroup analysis, it was strongly suggested that the genetic effects come from the ADH1B*47Arg/*47Arg genotype, and that the positive signals from other sites are just tracking the genetic effect of ADH1B His47Arg. In this article we present summaries of previous studies and of the present study, to give an overview of the worldwide effects of ADH1B His47Arg on the risk of alcoholism. The information derived from this study could be valuable for understanding the genetic factors involved in the risk of alcoholism and facilitate further investigation in other ethnic groups.

Genetic polymorphisms of ADH2, ADH3, CYP4502E1 Dra-I and Pst-I, and ALDH2 in Spanish men: lack of association with alcoholism and alcoholic liver disease

BACKGROUND/AIMS

The relationship between polymorphisms at the alcohol dehydrogenase 2 (ADH(2)), ADH(3), CYP(450)2E1 and aldehyde dehydrogenase 2 (ALDH(2)) loci and the individual predisposition to alcoholism and alcoholic liver disease in Caucasians is controversial.

METHODS

We determined the genotypes of ADH(2), ADH(3), CYP(450)2E1 (Pst-I and Dra-I) and ALDH(2) in 519 male Spaniards: 264 alcoholic subjects (47 without liver disease, 118 with non-cirrhotic liver disease and 99 with cirrhosis) and 255 non-alcoholic subjects (64 healthy controls, 110 with non-cirrhotic non-alcoholic liver disease and 81 with cirrhosis unrelated to alcohol). Genotyping was performed using PCR-RFLP methods on white cell DNA.

RESULTS

The distribution of the allelic variants (allele *1 and allele *2) in the whole subjects analyzed was: ADH(2) 93.1% and 6.9%; ADH(3) 55.7 and 44.3%; CYP(450)2E1 Dra-I 11.2 and 88.8%; CYP(450)2E1 Pst-I 96.2 and 3.8% and ALDH2 100 and 0%, respectively. No differences were observed in the allelic distributions of the alcoholic and non-alcoholic subjects for the loci examined. Allele distribution in alcoholics with no liver disease, with alcoholic steatosis or hepatitis, and with cirrhosis was also similar.

CONCLUSIONS

ADH(2), ADH(3), and CYP(450)2E1 Pst-I and Dra-I genetic variations are not related to alcoholism or susceptibility to alcoholic liver disease in our male population. ALDH(2) locus is monomorphic.

Genetic polymorphism of alcohol dehydrogenase in europeans: the ADH2*2 allele decreases the risk for alcoholism and is associated with ADH3*1

Polymorphism at the ADH2 and ADH3 loci of alcohol dehydrogenase (ADH) has been shown to have an effect on the predisposition to alcoholism in Asian individuals. However, the results are not conclusive for white individuals. We have analyzed the ADH genotype of 876 white individuals from Spain (n = 251), France (n = 160), Germany (n = 184), Sweden (n = 88), and Poland (n = 193). Peripheral blood samples from healthy controls and groups of patients with viral cirrhosis and alcohol-induced cirrhosis, as well as alcoholics with no liver disease, were collected on filter paper. Genotyping of the ADH2 and ADH3 loci was performed using polymerase chain reaction-restriction fragment length polymorphism methods on white cell DNA. In healthy controls, ADH2*2 frequencies ranged from 0% (France) to 5.4% (Spain), whereas ADH3*1 frequencies ranged from 47. 6% (Germany) to 62.5% (Sweden). Statistically significant differences were not found, however, between controls from different countries, nor between patients with alcoholism and/or liver disease. When all individuals were grouped in nonalcoholics (n = 451) and alcoholics (n = 425), ADH2*2 frequency was higher in nonalcoholics (3.8%) than in alcoholics (1.3%) (P =.0016), whereas the ADH3 alleles did not show differences. Linkage disequilibrium was found between ADH2 and ADH3, resulting in an association of the alleles ADH2*2 and ADH3*1, both coding for the most active enzymatic forms. In conclusion, the ADH2*2 allele decreases the risk for alcoholism, whereas the ADH2*2 and ADH3*1 alleles are found to be associated in the European population.