Chinese alcoholic patients with esophageal cancer are genetically different from alcoholics with acute pancreatitis and liver cirrhosis

ALDH2 Polymorphism rs671 *1/*2 Genotype is a Risk Factor for the Development of Alcoholic Liver Cirrhosis in Hakka Alcoholics

Background

Alcoholics are prone to alcoholic cirrhosis (ALC). Aldehyde dehydrogenase 2 (ALDH2) is involved in alcohol metabolism. Herein, the relationship between ALDH2 genotypes and ALC was analyzed among Hakka alcoholics in southern China.

Methods

A total of 213 alcoholics and 214 non-alcoholics were included in the study. The ALDH2 gene rs671 polymorphism was analyzed, life history, disease history, and auxiliary examination results of these participants were collected.

Results

The alcoholics had higher level of total serum protein, and serum globulin, lower level of serum albumin, serum albumin/globulin ratio, serum prealbumin, neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR) than non-alcoholics. In the 213 alcoholics, 180 developed ALC. There were 206 non-ALC persons in the 214 non-alcoholics. The proportion of the ALDH2 rs671 G/G homozygous (*1/*1) was significantly lower in ALC patients (83.3%) than that of other groups (100.0% in non-ALC in alcoholics, 95.6% in non-ALC in non-alcoholics), while the proportion of the G/A heterozygous (*1/*2) was significantly higher in ALC patients (16.7%) than that of other groups (0% in non-ALC in alcoholics, 4.4% in non-ALC in non-alcoholics). Logistic regression analysis indicated that participants with low level of NLR (adjusted OR 5.543, 95% CI 2.964–10.368, P<0.001), LMR (adjusted OR 9.256, 95% CI 4.740–18.076, P<0.001), and PLR (adjusted OR 6.047, 95% CI 3.372–10.845, P<0.001), and ALDH2 G/A genotype (adjusted OR 6.323, 95% CI 2.477–16.140, P<0.001) had a significantly higher risk of ALC.

Conclusion

ALDH2 polymorphism rs671 *1/*2 genotype is a potential risk factor for the development of ALC among Hakka alcoholics.

Association between aldehyde dehydrogenase 2 gene rs671 G>A polymorphism and alcoholic liver cirrhosis in southern Chinese Hakka population

BACKGROUND

Alcoholic liver cirrhosis (ALC) endangering people's health. The association between aldehyde dehydrogenase 2 (ALDH2) gene polymorphisms and ALC is not clear. To analyze the relationship between ALDH2 and ALC among Hakka population in southern China.

METHODS

A total of 292 ALC patients and 278 controls were included in the study. The ALDH2 gene rs671 polymorphism was analyzed by polymerase chain reaction (PCR)-gene chip. Relevant information and medical records of these participants were collected.

RESULTS

The ALC patients had higher percentage of smoking, lower prevalence of hypertension, higher level of alanine aminotransferase (ALT), aspertate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), total bile acid (TBA), total bilirubin (Tbil), and direct bilirubin (Dbil), lower level of total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C) than controls. The proportions of the G/A genotype (p = 0.017), G/A plus A/A genotype (p = 0.023) and A allele (p = 0.031) were significantly higher in ALC patients than that of controls. ALC patients with G/A genotype had higher TC, HDL-C, and Apo-A1 than those with G/G genotype, while with A allele had higher HDL-C, and Apo-A1 than those with G allele. Logistic regression analysis indicated that ALDH2 SNP rs671 G/A plus A/A genotypes (A allele carriers) (OR 2.030, 95% CI 1.109-3.715, p = 0.022) in the dominant model was the risk factor for ALC.

CONCLUSIONS

ALDH2 A allele (G/A + A/A genotypes) increased the risk of developing ALC among Hakka people in southern China. The results should enrich the relevant data and provide valuable information for the future related research.

Association between genetic variants in CYP2E1 and CTRC genes and susceptibility to alcoholic pancreatitis: A systematic review and meta-analysis

BACKGROUND

Genetic predisposition plays an important role in the development of alcoholic pancreatitis (AP), with previous studies suggesting that genetics variants in certain genes, such asCYP2E1 and CTRC, partially explain individual susceptibility to this disease. Therefore, the aim of this work was to conduct a systematic review and meta-analysis of existing studies that analyzed how polymorphisms within CYP2E1 and CTRC genes influence the risk of AP.

MATERIAL AND METHODS

We performed a systematic review of studies that analyzed the genotype distribution of CYP2E1 and CTRC allelic variants among patients with AP and a group of controls. A meta-analysis was conducted using a random effects model. Odds ratios (ORs) and their confidence intervals (CIs) were calculated.

RESULTS

The T allele of theCTRC 180 C > T variant was significantly more prevalent among patients with AP compared to all controls (OR = 1.79, 95% CI = 1.43-2.24; P < 0.00001) and healthy subjects (OR = 1.84, 95% CI = 1.46-2.31; P < 0.00001). The Trp variant of CTRC Arg254Trp polymorphism was also more prevalent in patients with AP; however, these results were not significant after excluding one study. We found no clear evidence that CYP2E1-DraI or of CYP2E1-RsaI/PstI polymorphisms modulate the risk of developing AP.

CONCLUSIONS

Our meta-analysis supports that the T allele ofCTRC 180C > T polymorphisms modulates the risk of alcoholic pancreatitis. No clear evidence was found for the remaining SNPs being associated with this disease.

Meta-analysis and field synopsis of genetic variants associated with the risk and severity of acute pancreatitis

Background

Genetic risk factors can provide insight into susceptibility for acute pancreatitis (AP) and disease progression towards (infected) necrotizing pancreatitis and persistent organ failure. The aim of the study was to undertake a systematic review of the genetic evidence for AP.

Methods

Online databases (MEDLINE, Embase, BIOSIS, Web of Science, Cochrane Library) were searched to 8 February 2018. Studies that reported on genetic associations with AP susceptibility, severity and/or complications were eligible for inclusion. Meta‐analyses were performed of variants that were reported by at least two data sources. Venice criteria and Bayesian false‐discovery probability were applied to assess credibility.

Results

Ninety‐six studies reporting on 181 variants in 79 genes were identified. In agreement with previous meta‐analyses, credible associations were established for SPINK1 (odds ratio (OR) 2·87, 95 per cent c.i. 1·89 to 4·34), IL1B (OR 1·23, 1·06 to 1·42) and IL6 (OR 1·64, 1·15 to 2·32) and disease risk. In addition, two novel credible single‐nucleotide polymorphisms were identified in Asian populations: ALDH2 (OR 0·48, 0·36 to 0·64) and IL18 (OR 1·47, 1·18 to 1·82). Associations of variants in TNF, GSTP1 and CXCL8 genes with disease severity were identified, but were of low credibility.

Conclusion

Genetic risk factors in genes related to trypsin activation and innate immunity appear to be associated with susceptibility to and severity of AP.

Effect of ALDH2 polymorphism on cancer risk in Asians: A meta-analysis

Numerous studies have investigated the association between ALDH2 gene rs671G>A polymorphism and various cancer type in Asians. However, the results remain inconclusive.We conducted a comprehensive meta-analysis including 63 articles with 66 studies containing 25,682 cases and 47,455 controls retrieved by searching PubMed and Embase electronic databases up to March 5, 2018.Pooled results indicated that ALDH2 gene rs671 polymorphism was significantly associated with the overall cancer risk in Asians (homozygous model: odds ratio [OR] = 0.85, 95% confidence interval [CI] = 0.72-0.99, P = .042; heterozygous model: OR = 1.32, 95% CI = 1.14-1.52, P  < .001; recessive model: OR = 0.73, 95% CI = 0.60-0.88, P = .001; dominant model: OR = 1.32, 95% CI = 1.16-1.51, P < .001; and allele comparison model: OR = 1.11, 95% CI = 1.03-1.19, P = .004), especially in esophageal cancer and among the Chinese and the Japanese.Our results suggest that ALDH2 rs671 polymorphism is associated with the overall cancer risk in Asians. Well-designed prospective studies with more information about gene-environment interaction, such as drinking, should be conducted to validate our findings.

Association of ALDH3B2 gene polymorphism and risk factors with susceptibility of esophageal squamous cell carcinoma in a Chinese population: a case-control study involving 2,358 subjects

Background

Esophageal cancer (EC) is the sixth leading cause of cancer-associated death worldwide. The interaction of environmental risk factors and genetic factors might contribute to the carcinogenesis of EC synergistically.

Results

All seven single locus polymorphisms of ALDH3B2 were not associated with risk of ESCC as evaluated by allelic, dominant, co-dominant, recessive and Cochran-Armitage trend tests. Stratified analyses showed these SNPs were not correlated with the susceptibility of ESCC according to different age, gender, cigarette smoking and alcohol drinking status. None of the major haplotypes were related with ESCC susceptibility.

Materials and Methods

We conducted a hospital-based case-control study to evaluate the combined effects of environmental risk factors and the single nucleotide polymorphisms (SNPs) of ALDH3B2 gene on the development of esophageal squamous carcinoma (ESCC). A total of 1043 ESCC cases and 1315 controls were recruited for this study. Seven ALDH3B2 SNPs and four environmental factors were selected as independent variables. ALDH3B2 SNPs were determined by ligation detection reaction method.

Conclusions

Our study suggested that ALDH3B2 rs34589365, rs3741172, rs4646823, rs78402723, rs7947978, rs866907 and rs9787887 polymorphisms were not implicated with altered susceptibility of ESCC according to different age, gender, cigarette smoking and alcohol drinking status. Yet this conclusion needs to be verified in larger studies among different ethnic populations with validation design, the biological function of these SNPs in carcinogenesis are subject to further investigation.

Global trends in esophageal cancer

BACKGROUND AND OBJECTIVES

Esophageal Cancer (EC) is a lethal malignancy with poor prognosis and significant variations in the incidence, mortality, and histopathology based on geographic regions. The aim of this study was to quantitatively analyze these variations to identify patterns and areas for further research.

METHODS

We utilized the GLOBOCAN 2012, and Cancer Incidence in five Continents, Volume X (CI5X) database to analyze variations in EC incidence and mortality.

RESULTS

We found the EC incidence and mortality is geographically varied with a particularly high burden in East Asia and Eastern/Southern Africa where esophageal squamous cell carcinoma (SCC) predominates over adenocarcinoma (AC). Interestingly, there is a dichotomy between the high incidence of esophageal SCC in East Africa and low incidence in West Africa. The global incidence and mortality from EC is expected to rise in the coming decades. Asia, and China in particular, will continue to be the areas most burdened by EC, while Africa is expected to surpass the incidence and mortality rates of Europe.

CONCLUSIONS

The global burden of EC is expected to rise in the coming years. Understanding the geographic, environmental, and genetic contributors to the development of EC will be essential in combating its prevalence.

ALDH2-deficiency as genetic epidemiologic and biochemical model for the carcinogenicity of acetaldehyde

Humans are cumulatively exposed to acetaldehyde from various sources including alcoholic beverages, tobacco smoke, foods and beverages. The genetic-epidemiologic and biochemical evidence in ALDH2-deficient humans provides strong evidence for the causal relationship between acetaldehyde-exposure due to alcohol consumption and cancer of the upper digestive tract. The risk assessment has so far relied on thresholds based on animal toxicology with lower one-sided confidence limit of the benchmark dose values (BMDL) typically ranging between 11 and 63 mg/kg bodyweight (bw)/day dependent on species and endpoint. The animal data is problematic for regulatory toxicology for various reasons (lack in study quality, problems in animal models and appropriateness of endpoints - especially cancer - for transfer to humans). In this study, data from genetic epidemiologic and biochemical studies are reviewed. The increase in the daily exposure dose to acetaldehyde in alcohol-consuming ALDH2-deficients vs. ALDH2-actives was about twofold. The acetaldehyde increase due to ALDH2 inactivity was calculated to be 6.7 μg/kg bw/day for heavy drinkers, which is associated with odds ratios of up to 7 for head and neck as well as oesophageal cancer. Previous animal toxicology based risk assessments may have underestimated the risk of acetaldehyde. Risk assessments of acetaldehyde need to be revised using this updated evidence.

Association between alcohol dehydrogenase-2 gene polymorphism and esophageal cancer risk: a meta-analysis

BACKGROUND

It has been shown that gene polymorphisms may play an important role in the carcinogenesis of esophageal cancer. This study is to investigate the role of alcohol dehydrogenase 1B (ADH1B) gene Arg47His polymorphism in esophageal cancer susceptibility.

METHODS

Case-control studies published between January 2000 and June 2015 were searched to retrieve relevant articles. The pooled odds ratio (OR) and 95 % confidence interval (CI) were employed to calculate the strength of association.

RESULTS

A total of 23 relevant articles were finally selected for the analysis, including 9338 esophageal cancer patients and 14,896 matched controls. Overall, we found that the 47His allele was significant associated with the decreased risk of esophageal cancer when compared with the 47Arg allele in total populations (A vs. G: OR = 0.67, 95 % CI = 0.59-0.76, P < 0.00001). This protective relationship was observed under other genetic models as well (P < 0.00001). Subgroup analysis by ethnicity showed that ADH1B Arg47His variant was associated with the decreased esophageal cancer risk under all the genetic models (P < 0.00001) among Asians, especially in Chinese and Japanese; while in non-Asians, no significant correlation was detected in any genetic models (P > 0.05). Furthermore, Arg/Arg genotype of ADH1B Arg47His variant combined with drinking, smoking and males appeared to show a high risk in patients with esophageal cancer.

CONCLUSIONS

Our results suggested that ADH1B gene Arg47His variant was associated with the decreased esophageal cancer risk. Genetic-environmental interaction should be further considered in the future researches.

Aldehyde Dehydrogenase 2 (ALDH2) Polymorphism and the Risk of Alcoholic Liver Cirrhosis among East Asians: A Meta-Analysis

PURPOSE

The aldehyde dehydrogenase 2 (ALDH2) gene has been implicated in the development of alcoholic liver cirrhosis (ALC) in East Asians. However, the results are inconsistent. In this study, a meta-analysis was performed to assess the associations between the ALDH2 polymorphism and the risk of ALC.

MATERIALS AND METHODS

Relevant studies were retrieved by searching PubMed, Web of Science, CNKI, Wanfang and Veipu databases up to January 10, 2015. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using either the fixed- or random effects model.

RESULTS

A total of twelve case-control studies included 1003 cases and 2011 controls were included. Overall, the ALDH2 polymorphism was associated with a decreased risk of ALC (*1/*2 vs. *1/*1: OR=0.78, 95% CI: 0.61-0.99). However, in stratification analysis by country, we failed to detect any association among Chinese, Korean or Japanese populations.

CONCLUSION

The pooled evidence suggests that ALDH2 polymorphism may be an important protective factor for ALC in East Asians.

Clinical significance of ALDH2 rs671 polymorphism in esophageal cancer: evidence from 31 case-control studies

Background

Aldehyde dehydrogenase 2 (ALDH2), a critical enzyme for the detoxification of alcohol, is associated with many types of cancers. To verify the relationship of ALDH2 rs671 G>A polymorphism and esophageal cancer (EC), we performed a meta-analysis of a total of 31 published data including 8,510 patients and 16,197 controls.

Methods

The pooled odds ratio (OR) and the 95% confidence interval (CI) were calculated using a fixed or random-effects model. Heterogeneity (P_H), publication bias, and sensitivity analysis were also determined.

Results

Although a protective effort was found in the rs671 homozygote comparison (AA/GG: OR=0.69; 95% CI=0.48–0.98), the heterozygote comparison was apparently associated with the risk of EC, particularly in the Chinese population (AG/GG: OR=1.39; 95% CI=1.03–1.87). Alcohol consumption remarkably increased this risk, especially in the AG genotype. Drinking men with the AG genotype appeared to show a higher risk (AG/GG: OR=4.39; 95% CI=1.24–6.55) than drinking women.

Conclusion

The present meta-analysis provided advanced information regarding the association of the ALDH2 A>G polymorphism and EC. Taken together, insights from this study suggested an enhanced effect on the development of EC through a genetic–environmental interaction.

Association between Glu504Lys polymorphism of ALDH2 gene and cancer risk: a meta-analysis

Background

The association of the aldehyde dehydrogenases-2 (ALDH2) Glu504Lys polymorphism (also named Glu487Lys, or rs671) and cancers has been investigated. This meta-analysis aims to comprehensively assess the influence of this polymorphism on the overall cancer risk.

Methods

Eligible publications were retrieved according to inclusion/exclusion criteria and the data were analyzed using the Review Manager software (V5.2).

Results

A meta-analysis based on 51 case-control studies consisting of 16774 cases and 32060 controls was performed to evaluate the association between the ALDH2 Glu504Lys polymorphism and cancer risk. The comparison of genotypes Lys+ (Lys/Lys and Lys/Glu) with Glu/Glu yielded a significant 20% increased cancer risk (OR = 1.20, 95%CI: 1.03–1.39, P = 0.02, I² = 92%). Subgroup analysis by cancer type indicated a significantly increased UADT cancer risk (OR = 1.39, 95%CI: 1.11–1.73, P = 0.004, I² = 94%) in individuals with the Lys+ genotypes. Subgroup analysis by country indicated that individuals from Japan with the Lys+ genotypes had a significant 38% increased cancer risk (OR = 1.38, 95%CI: 1.12–1.71, P = 0.003, I² = 93%).

Conclusions

Our results indicated that the ALDH2 Glu504Lys polymorphism is a susceptible loci associated with overall cancers, especially esophageal cancer and among Japanese population.

Genetic polymorphisms in alcohol dehydrogenase, aldehyde dehydrogenase and alcoholic chronic pancreatitis susceptibility: a meta-analysis

PURPOSE

This study was aimed to determine the relationship of alcohol-metabolizing enzymes ADH2, ADH3, and ALDH2 polymorphisms with the susceptibility to alcoholic chronic pancreatitis (ACP).

METHODS

Meta-analyses that evaluated the association of ADH2, ADH3, and ALDH2 variations with ACP were performed.

RESULTS

Eight case-control studies were selected for analysis. The overall data revealed a significant association of ADH2 polymorphism (OR=1.56, 95% CI=1.42-1.72, P=0.000 for dominant model; OR=1.63, 95% CI=1.55-1.71, P=0.000 for homozygote comparison model; OR=1.11, 95% CI=1.01-1.22, P=0.030 for allelic contrast model), ADH3 polymorphism (OR=0.95, 95% CI=0.86-1.06, P=0.389 for dominant; OR=0.64, 95% CI=0.44-0.93, P=0.020 for homozygote comparison; and OR=0.87, 95% CI=0.77-0.99, P=0.039 for allelic contrast model) and ALDH2 polymorphism (OR=0.57, 95% CI=0.40-0.81, P=0.002 for dominant; OR=0.50, 95% CI=0.23-1.08, P=0.079 for homozygote comparison; and OR=0.58, 95% CI=0.41-0.84, P=0.003 for allelic contrast model) with ACP risk. The subgroup analyses suggested that the variant ADH2*2/*2+*1/*2, ADH2*2/*2 genotype and ADH2*2 allele significantly increased ACP risk among Asian individuals; the variant ADH3*2/*2 genotype and ADH3*2 allele significantly decreased ACP risk among non-Asian individuals; and the variant ALDH2*2/*2+*1/*2 genotype and ALDH2*2 allele significantly decreased ACP risk among Asians.

CONCLUSIONS

ADH2, ADH3 and ALDH2 polymorphisms may be susceptibility facts of ACP, and it may be ethnic and race-dependent.

Genetic variation in alcohol metabolizing enzymes among Inuit and its relation to drinking patterns

BACKGROUND

Variation in genes involved in alcohol metabolism is associated with drinking patterns worldwide. We compared variation in these genes among the Inuit with published results from the general population of Denmark and, due to the Asian ancestry of the Inuit, with Han Chinese. We analyzed the association between gene variations and drinking patterns among the Inuit.

METHODS

We genotyped 4162 Inuit participants from two population health surveys. Information on drinking patterns was available for 3560. Seven single nucleotide polymorphisms (SNPs) were examined: ADH1B arg48his, ADH1C ile350val, ADH1C arg272gln, ALDH2 glu504lys, ALDH2 5'-UTR A-357G, ALDH1B1 ala86val and ALDH1B1 arg107leu.

RESULTS

The allele distribution differed significantly between Inuit and the general population of Denmark. A protective effect on heavy drinking was found for the TT genotype of the ALDH1B1 arg107leu SNP (OR=0.59; 95% CI 0.37-0.92), present in 3% of pure Inuit and 37% of Danes. The ADH1C GG genotype was associated with heavy drinking and a positive CAGE test (OR 1.34; 95% CI 1.05-1.72). It was present in 27% of Inuit and 18% of Danes. The Asian genotype pattern with a high frequency of the ADH1B A allele and an ALDH2 gene coding for an inactive enzyme was not present in Greenland.

CONCLUSIONS

ADH1C and ALDH1B1 arg107leu SNPs play a role in the shaping of drinking patterns among the Inuit in Greenland. A low frequency of the ALDH1B1 arg107leu TT genotype compared with the general population in Denmark deserves further study. This genotype was protective of heavy drinking among the Inuit.

Tag single nucleotide polymorphisms of alcohol-metabolizing enzymes modify the risk of upper aerodigestive tract cancers: HapMap database analysis

Although alcohol is associated with higher upper aerodigestive tract (UADT) cancer risk, only a small fraction of alcoholics develop cancers. There is a lack of evidence proving the association of tag single nucleotide polymorphisms of alcohol-metabolizing enzymes with cancer risk. The aim of this study was to determine the association of these genetic polymorphisms with UADT cancer risk in a Chinese population. It was a hospital-based case-control candidate gene study. The databases of the International HapMap Project were searched for haplotype tag single nucleotide polymorphisms of the genes alcohol dehydrogenase (ADH)1B, ADH1C, and aldehyde dehydrogenase (ALDH)2. The genotyping was performed by the Sequenom MassARRAY system. Totally, 120 head and neck squamous cell carcinoma, 138 esophageal squamous cell carcinoma patients, and 276 age- and gender-matched subjects were enrolled between June 2008 and June 2010.Minor alleles of ADH1B (rs1229984) and ALDH2(rs671) were not only associated with the risk of UADT cancers (odds ratio [OR] [95% confidence interval, CI]: 3.53 [2.14-5.80] and 2.59 [1.79-3.75], respectively) but also potentiated the carcinogenic effects of alcohol (OR [95% CI]: 53.44 [25.21-113.29] and 70.08 [33.65-145.95], respectively). Similar effects were observed for head/neck and esophageal cancer subgroups. Multivariate logistic regression analysis identified four significant risk factors, including habitual use of cigarettes, alcohol, betel quid, and lower body mass index (P < 0.001). The haplotypes GAGC (OR 1.61, 95% CI 1.08-2.40, P = 0.018) and CCAATG (OR 1.69, 95% CI 1.24-2.30, P < 0.001) on chromosomes 4 and 12, respectively, were associated with higher cancer risk. These findings suggested that risk allele or haplotype carriers who consume alcohol and other carcinogens should be advised to undergo endoscopy screening. The information can be used to determine the degree of susceptibility of each subject and can be combined with other environmental factors, like carcinogen consumption, in the screening analysis.

Aldehyde dehydrogenase 2 deficiency ameliorates alcoholic fatty liver but worsens liver inflammation and fibrosis in mice

Aldehyde dehydrogenase 2 (ALDH2) is the major enzyme that metabolizes acetaldehyde produced from alcohol metabolism. Approximately 40-50% of East Asians carry an inactive ALDH2 gene and exhibit acetaldehyde accumulation after alcohol consumption. However, the role of ALDH2 deficiency in the pathogenesis of alcoholic liver injury remains obscure. In the present study, wild-type and ALDH2(-/-) mice were subjected to ethanol feeding and/or carbon tetrachloride (CCl4 ) treatment, and liver injury was assessed. Compared with wild-type mice, ethanol-fed ALDH2(-/-) mice had higher levels of malondialdehyde-acetaldehyde (MAA) adduct and greater hepatic inflammation, with higher hepatic interleukin (IL)-6 expression but surprisingly lower levels of steatosis and serum alanine aminotransferase (ALT). Higher IL-6 levels were also detected in ethanol-treated precision-cut liver slices from ALDH2(-/-) mice and in Kupffer cells isolated from ethanol-fed ALDH2(-/-) mice than those levels in wild-type mice. In vitro incubation with MAA enhanced the lipopolysaccharide (LPS)-mediated stimulation of IL-6 production in Kupffer cells. In agreement with these findings, hepatic activation of the major IL-6 downstream signaling molecule signal transducer and activator of transcription 3 (STAT3) was higher in ethanol-fed ALDH2(-/-) mice than in wild-type mice. An additional deletion of hepatic STAT3 increased steatosis and hepatocellular damage in ALDH2(-/-) mice. Finally, ethanol-fed ALDH2(-/-) mice were more prone to CCl4 -induced liver inflammation and fibrosis than ethanol-fed wild-type mice.

CONCLUSION

ALDH2(-/-) mice are resistant to ethanol-induced steatosis but prone to inflammation and fibrosis by way of MAA-mediated paracrine activation of IL-6 in Kupffer cells. These findings suggest that alcohol, by way of acetaldehyde and its associated adducts, stimulates hepatic inflammation and fibrosis independent from causing hepatocyte death, and that ALDH2-deficient individuals may be resistant to steatosis and blood ALT elevation, but are prone to liver inflammation and fibrosis following alcohol consumption.

Single nucleotide polymorphisms of ADH1B, ADH1C and ALDH2 genes and esophageal cancer: a population-based case-control study in China

Alcohol drinking is a major risk factor for esophageal cancer (EC) and the metabolism of ethanol has been suggested to play an important role in esophageal carcinogenesis. Epidemiologic studies, including genomewide association studies (GWAS), have identified single nucleotide polymorphisms (SNPs) in alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs) to be associated with EC. Using a population-based case-control study with 858 EC cases and 1,081 controls conducted in Jiangsu Province, China, we aimed to provide further information on the association of ADH1B (rs1229984), ADH1C (rs698) and ALDH2 (rs671) polymorphisms with EC in a Chinese population. Results showed that ADH1B (rs1229984) was associated with EC with odds ratios (ORs) of 1.34 [95% confidence interval (CI): 1.08-1.66] for G-allele carriers compared to A/A homozygotes. No heterogeneity was detected on this association across different strata of alcohol drinking and tobacco smoking. Statistical interaction between ALDH2 (rs671) and alcohol drinking on EC susceptibility in both additive and multiplicative scales was observed. Compared to G/G homozygotes, A-allele carriers were positively associated with EC among moderate/heavy drinkers (OR = 1.64, 95% CI: 1.12-2.40) and inversely associated with EC among never/light drinks (OR = 0.75, 95% CI: 0.54-1.03). In addition, statistical interaction between ALDH2 and ADH1B polymorphisms on EC susceptibility among never/light drinkers was indicated. We did not observe association of ADH1C polymorphism with EC. In conclusion, our findings indicated that ADH1B (rs1229984) was associated with EC independent of alcohol drinking and tobacco smoking status and alcohol drinking interacted with ALDH2 (rs671) on EC susceptibility in this high-risk Chinese population.

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.

ADH1C Ile350Val polymorphism and cancer risk: evidence from 35 case-control studies

BACKGROUND

Alcohol dehydrogenase 1C (ADH1C) is the key enzyme catalyze oxidation of alcohol to acetaldehyde, which plays vital roles in the etiology of various cancer. To date, studies investigated the association between a functional polymorphism in ADH1C, Ile350Val (rs698), and risk of cancer have shown inclusive results.

METHODS

A meta-analysis based on 35 case-control studies was performed to address this issue. Odds ratios (OR) with 95% confidence intervals (CIs) were used to assess the association. The statistical heterogeneity across studies was examined with χ2-based Q-test.

RESULTS

Overall, no significant associations between ADH1C Ile350Val polymorphism and cancer risk were observed in any genetic models (P>0.05). In the stratified analyses, there was a significantly increased cancer risk among African (Val/Val vs. Ile/Ile OR  =  2.19, 95% CI  =  1.29-3.73, P(heterogeneity)  =  0.989; Ile/Val + Val/Val vs. Ile/Ile: OR  =  1.79, 95%CI  =  1.18-2.71, P(heterogeneity)  =  0.761; Val/Val vs. Ile/Val + Ile/Ile: OR  =  1.92, 95% CI  =  1.16-3.17, P(heterogeneity)  =  0.981) and Asian (Ile/Val vs. Ile/Ile: OR  =  1.58, 95% CI  =  1.32-1.90, P(heterogeneity)  =  0.375; Val/Val vs. Ile/Ile: OR  =  3.84, 95% CI  =  1.74-8.49, P(heterogeneity)  =  0.160; Ile/Val + Val/Val vs. Ile/Ile: OR  =  1.65, 95% CI  =  1.38-1.96, P(heterogeneity)  =  0.330; Val/Val vs. Ile/Val + Ile/Ile: OR  =  3.54, 95% CI  =  1.62-7.75, P(heterogeneity)  =  0.154) studies.

CONCLUSIONS

The results indicate that ADH1C Ile350Val polymorphism may contribute to cancer risk among Africans and Asians. Additional comprehensive system analyses are required to validate this association combined with other related polymorphisms.

Strong protective effect of the aldehyde dehydrogenase gene (ALDH2) 504lys (*2) allele against alcoholism and alcohol-induced medical diseases in Asians

Alcohol is oxidized to acetaldehyde, which in turn is oxidized to acetate. The aldehyde dehydrogenase 2 gene (ALDH2) is the most important gene responsible for acetaldehyde metabolism. Individuals heterozygous or homozygous for the lys (A or *2) allele at the single nucleotide polymorphism (SNP) glu504lys (rs671) of ALDH2 have greatly reduced ability to metabolize acetaldehyde, which greatly decreases their risk for alcohol dependence (AD). Case-control studies have shown association between this SNP and alcohol dependence as well as alcohol-induced liver disease. However, some studies have produced insignificant results. Using cumulative data from the past 20 years predominately from Asian populations (from both English and Chinese publications), this meta-analysis sought to examine and update whether the aggregate data provide new evidence of statistical significance for the proposed association. Our results (9,678 cases and 7,331 controls from 53 studies) support a strong association of alcohol abuse and dependence, with allelic P value of 3 × 10(-56) and OR of 0.23 (0.2, 0.28) under the random effects model. The dominant model (lys-lys + lys-glu vs. glu-glu) also showed strong association with P value of 1 × 10(-44) and OR of 0.22 (0.18, 0.27). When stricter criteria and various sub-group analyses were applied, the association remained strong (for example, OR = 0.23 (0.18, 0.3) and P = 2 × 10(-28) for the alcoholic patients with alcoholic liver disease, cirrhosis, or pancreatitis). These findings provide confirmation of the involvement of the human ALDH2 gene in the pathogenesis of AD as well as alcohol-induced medical illnesses in East-Asians.

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.

Alcohol dehydrogenase-1B Arg47His polymorphism and upper aerodigestive tract cancer risk: a meta-analysis including 24,252 subjects

BACKGROUND

Cancers of the upper aerodigestive tract (UADT) include malignant tumors of the oral cavity, pharynx, larynx, and esophagus, account for approximately 4% of all new cancers in world. Alcohol drinking is an established risk factor for UADT cancers, and the rate of alcohol metabolism could significantly been influenced by genetic polymorphisms of alcohol dehydrogenase-1B (ADH1B) His47Arg (rs1229984). To evaluate whether combined evidence shows ADH1B His47Arg as a common genetic variant that influenced the risk of UADT cancers, we considered all available studies in a meta-analysis.

METHODS

Eighteen studies were combined representing data of 8,539 cases and 15,713 controls for meta-analysis. Stratified analyses were carried out to determine the gene-environment interaction between ADH1B His47Arg and alcohol drinking and gene-gene interaction between ADH1B His47Arg and aldehyde dehydrogenase-2 (ALDH2) Glu/Lys related to UADT cancer risk. Potential sources of heterogeneity between studies were explored; sensitivity analysis and publication bias was also evaluated.

RESULTS

The ADH1B 47Arg allele was found to be associated with increased risk of UADT cancers, the pooled odds ratios (ORs) being 1.66 (95% CI: 1.54 to 1.79) and 3.47 (95% CI: 2.76 to 4.36) for the His/Arg and Arg/Arg genotypes compared with the His/His genotype, respectively. An 18.48-fold increase in OR (95% CI: 12.95 to 26.40) for UADT cancers among alcohol drinkers with Arg/Arg genotype was found, when compared among nondrinkers with the His/His genotype. Significant interaction between carriers with ADH1B 47Arg and ALDH2 487Lys allele related to risk for UADT cancers was more evident, compared with noncarriers (OR = 10.31, 95% CI: 5.45 to 18.85).

CONCLUSIONS

ADH1B 47Arg allele is a common genetic variant that increased the risk of UADT cancers; furthermore, it modulates the susceptibility to UADT cancers coupled with alcohol drinking and interaction with the ALDH2 487Lys allele.

Alcohol and aldehyde dehydrogenase polymorphisms and a new strategy for prevention and screening for cancer in the upper aerodigestive tract in East Asians

The ethanol in alcoholic beverages and the acetaldehyde associated with alcohol consumption are Group 1 human carcinogens (WHO, International Agency for Research on Cancer). The combination of alcohol consumption, tobacco smoking, the inactive heterozygous aldehyde dehydrogenase-2 genotype (ALDH2*1/*2) and the less-active homozygous alcohol dehydrogenase-1B genotype (ADH1B*1/*1) increases the risk of squamous cell carcinoma (SCC) in the upper aerodigestive tract (UADT) in a multiplicative fashion in East Asians. In addition to being exposed to locally high levels of ethanol, the UADT is exposed to a very high concentration of acetaldehyde from a variety of sources, including that as an ingredient of alcoholic beverages per se and that found in tobacco smoke; acetaldehyde is also produced by salivary microorganisms and mucosal enzymes and is present as blood acetaldehyde. The inefficient degradation of acetaldehyde by weakly expressed ALDH2 in the UADT may be cri! tical to the local accumulation of acetaldehyde, especially in ALDH2*1/*2 carriers. ADH1B*1/*1 carriers tend to experience less intense alcohol flushing and are highly susceptible to heavy drinking and alcoholism. Heavy drinking by persons with the less-active ADH1B*1/*1 leads to longer exposure of the UADT to salivary ethanol and acetaldehyde. The ALDH2*1/*2 genotype is a very strong predictor of synchronous and metachronous multiple SCCs in the UADT. High red cell mean corpuscular volume (MCV), esophageal dysplasia, and melanosis in the UADT, all of which are frequently found in ALDH2*1/*2 drinkers, are useful for identifying high-risk individuals. We invented a simple flushing questionnaire that enables prediction of the ALDH2 phenotype. New health appraisal models that include ALDH2 genotype, the simple flushing questionnaire, or MCV are powerful tools for devising a new strategy for prevention and screening for UADT cancer in East Asians.

Meta-analysis of ADH1B and ALDH2 polymorphisms and esophageal cancer risk in China

AIM: To evaluate whether alcohol dehydrogenase-1B (ADH1B) His47Arg and aldehyde dehydrogenase-2 (ALDH2) Glu487Lys polymorphism is involved in the esophageal squamous cell carcinoma (ESCC) risk in Chinese Han population.

METHODS: Seven studies of ADH1B and ALDH2 genotypes in Chinese Han population in 1450 cases and 2459 controls were included for meta-analysis. Stratified analyses were carried out to determine the gene-alcohol and gene-gene interaction with ESCC risk. Potential sources of heterogeneity between studies were explored, and publication bias was also evaluated.

RESULTS: Individuals with ADH1B arginine (Arg)/Arg genotype showed 3.95-fold increased ESCC risk in the recessive genetic model [Arg/Arg vs Arg/histidine (His) + His/His: odds ratio (OR) = 3.95, 95% confidence interval (CI): 2.76-5.67]. Significant association was found in the dominant model for ALDH2 lysine (Lys) allele [glutamate (Glu)/Lys + Lys/Lys vs Glu/Glu: OR = 2.00, 95% CI: 1.54-2.61]. Compared with the non-alcoholics, Arg/Arg (OR = 25.20, 95% CI: 10.87-53.44) and Glu/Lys + Lys/Lys (OR = 21.47, 95% CI: 6.44-71.59) were found to interact with alcohol drinking to increase the ESCC risk. ADH1B Arg+ and ALDH2 Lys+ had a higher risk for ESCC (OR = 7.09, 95% CI: 2.16-23.33).

CONCLUSION: The genetic variations of ADH1B His47Arg and ALDH2 Glu487Lys are susceptible loci for ESCC in Chinese Han population and interact substantially with alcohol consumption. The individuals carrying both risky genotypes have a higher baseline risk of ESCC.

Relationship between genetic polymorphisms of ALDH2 and ADH1B and esophageal cancer risk: A meta-analysis

AIM: To evaluate the contribution of alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) polymorphisms to the risk of esophageal cancer.

METHODS: Nineteen articles were included by searching MEDLINE, EMBASE and the Chinese Biomedical Database, 13 on ADH1B and 18 on ALDH2. We performed a meta-analysis of case-control studies including 13 studies on ADH1B (cases/controls: 2390/7100) and 18 studies on ALDH2 (2631/6030).

RESULTS: The crude odds ratio [OR (95% confidence interval)] was 2.91 (2.04-4.14) for ADH1B*1/*1 (vs ADH1B*2/*2) and 1.32 (1.17-1.49) for ADH1B*1/*2. The crude OR for ALDH2*1/*2 (vs ALDH2*1/*1) was 2.52 (1.76-3.61). ADH1B*1/*1 increased the risk of esophageal cancer among never/rare [1.56 (0.93-2.61)], moderate [2.71 (1.37-5.35)], and heavy drinkers [3.22 (2.27-4.57)]. ADH1B*1/*2 was associated with a modest risk among moderate drinkers [1.43 (1.09-1.87)]. ALDH2*1/*2 increased the risk among never/rare [1.28 (0.91-1.80)], moderate [3.12 (1.95-5.01)], and heavy [7.12 (4.67-10.86)] drinkers, and among ex-drinkers [5.64 (1.57-20.25)]. ALDH2*2/*2 increased the risk among drinkers [4.42 (1.72-11.36)]. ADH1B*1/*1 plus ALDH2*1/*2 was associated with the highest risk for heavy drinkers [12.45 (2.9-53.46)]. The results of the meta-regression analysis showed that the effects of ADH1B*1/*1 and ALDH2*1/*2 increased with the level of alcohol consumption. ALDH2*1/*2 was associated with a high risk among Taiwan Chinese and Japanese drinkers, as opposed to a moderate risk among drinkers in high-incidence regions of Mainland China. ADH1B*1/*1 in heavy drinkers and ALDH2*1/*2 in moderate-to-heavy drinkers was associated with similarly high risk among both men and women.

CONCLUSION: ADH1B/ALDH2 genotypes affect the risk of esophageal cancer, and the risk is modified by alcohol consumption, ethnicity, and gender.

Management of esophageal carcinoma associated with cirrhosis: a retrospective case-control analysis

Objectives. Esophageal carcinoma and cirrhosis have the overlapping etiologic factors. Methods. In a retrospective analysis conducted in 2 Breton institutions we wanted to asses the frequency of this association and the outcome of these patients in a case-control study where each case (cirrhosis and esophageal cancer) was paired with two controls (esophageal cancer). Results. In a 10-year period, we have treated 958 esophageal cancer patients; 26 (2.7%) had a cirrhosis. The same treatments were proposed to the 2 groups; cases received nonsignificantly different radiation and chemotherapy dose than controls. Severe toxicities and deaths were more frequent among the cases. At the end of the treatment 58% of the cases and 67% of the controls were in complete remission; median and 2-year survival were not different between the 2 groups. All 4 Child-Pugh B class patients experienced severe side effects and 2 died during the treatment. Conclusions. This association is surprisingly infrequent in our population! Child-Pugh B patients had a dismal prognosis and a bad tolerance to radiochemotherapy; Child-Pugh A patients have the same tolerance and the same prognosis as controls and the evidence of a well-compensated cirrhosis has not modified our medical options.

Polymorphisms of alcohol dehydrogenase-2 and aldehyde dehydrogenase-2 and esophageal cancer risk in Southeast Chinese males

AIM: To evaluate the impact of alcohol dehydrogenase-2 (ADH2) and aldehyde dehydrogenase-2 (ALDH2) polymorphisms on esophageal cancer susceptibility in Southeast Chinese males.

METHODS: Two hundred and twenty-one esophageal cancer patients and 191 healthy controls from Taixing city in Jiangsu Province were enrolled in this study. ADH2 and ALDH2 genotypes were examined by polymerase chain reaction and denaturing high-performance liquid chromatography. Unconditional logistic regression was used to calculate the odds ratios (OR) and 95% confidence interval (CI).

RESULTS: The ADH G allele carriers were more susceptible to esophageal cancer, but no association was found between ADH2 genotypes and risk of esophageal cancer when disregarding alcohol drinking status. Regardless of ADH2 genotype, ALDH2G/A or A/A carriers had significantly increased risk of developing esophageal cancer, with homozygous individuals showing higher esophageal cancer risk than those who were heterozygous. A significant interaction between ALDH2 and drinking was detected regarding esophageal cancer risk; the OR was 3.05 (95% CI: 1.49-6.25). Compared with non-drinkers carrying both ALDH2 G/G and ADH2 A/A, drinkers carrying both ALDH2 A allele and ADH2 G allele showed a significantly higher risk of developing esophageal cancer (OR = 8.36, 95% CI: 2.98-23.46).

CONCLUSION: Both ADH2 G allele and ALDH2 A allele significantly increase the risk of esophageal cancer development in Southeast Chinese males. ALDH2 A allele significantly increases the risk of esophageal cancer development especially in alcohol drinkers. Alcohol drinkers carrying both ADH2 G allele and ALDH2 A allele have a higher risk of developing esophageal cancer.

Effects of 5-week ethanol feeding on the liver of aldehyde dehydrogenase 2 knockout mice

OBJECTIVE

The polymorphism of aldehyde dehydrogenase 2 (ALDH2), denoted ALDH2*2, is very common in East Asian countries, and the mutated ALDH2 protein derived from ALDH2*2 lacks the ability of acetaldehyde metabolization. Our aim was to determine the consequences of the ALDH2 polymorphism on ethanol-administered liver tissue.

METHODS

Aldh2+/+, +/-, and -/- mice were fed with ethanol solution and standard hard feed for 5 weeks.

RESULTS

The serum alanine aminotransferase (ALT) level in the Aldh2-/- mice clearly decreased upon ethanol feeding, in contrast to Aldh2+/+ mice, in which the ALT level was unchanged. The levels of malondialdehyde, phospho extracellular signal-regulated kinase 2, and tumor necrosis factor-alpha in the liver tissue all correlated with the ALT level.

CONCLUSION

These findings suggest that ethanol intake in the presence of inactive ALDH2 decreases the serum ALT level following a decrease in oxidative stress and tumor necrosis factor-alpha secretion.

Polymorphisms of alcohol dehydrogenase 2 and aldehyde dehydrogenase 2 and colorectal cancer risk in Chinese males

AIM: To evaluate the relationship between drinking and polymorphisms of alcohol dehydrogenase 2 (ADH2) and/or aldehyde dehydrogenase 2 (ALDH2) for risk of colorectal cancer (CRC) in Chinese males.

METHODS: A case-control study was conducted in 190 cases and 223 population-based controls. ADH2 Arg47His (G-A) and ALDH2 Glu487Lys (G-A) genotypes were identified by PCR and denaturing high-performance liquid chromatography (DHPLC). Information on smoking and drinking was collected and odds ratio (OR) was estimated.

RESULTS: The ADH2 A/A and ALDH2 G/G genotypes showed moderately increased CRC risk. The age- and smoking-adjusted OR for ADH2 A/A relative to G/A and G/G was 1.60 (95% CI=1.08-2.36), and the adjusted OR for ALDH2 G/G relative to G/A and A/A was 1.79 (95% CI=1.19-2.69). Significant interactions between ADH2, ALDH2 and drinking were observed. As compared to the subjects with ADH2 G and ALDH2 A alleles, those with ADH2 A/A and ALDH2 G/G genotypes had a significantly increased OR (3.05, 95% CI= 1.67-5.57). The OR for CRC among drinkers with the ADH2 A/A genotype was increased to 3.44 (95% CI= 1.84-6.42) compared with non-drinkers with the ADH2 G allele. The OR for CRC among drinkers with the ALDH2 G/G genotype was also increased to 2.70 (95% CI= 1.57-4.66) compared with non-drinkers with the ALDH2 A allele.

CONCLUSION: Polymorphisms of the ADH2 and ALDH2 genes are significantly associated with CRC risk. There are also significant gene-gene and gene-environment interactions between drinking and ADH2 and ALDH2 polymorphisms regarding CRC risk in Chinese males.

Genetic polymorphisms of alcohol metabolising enzymes: their role in susceptibility to oesophageal cancer

BACKGROUND

Alcohol is a major risk factor for susceptibility to oesophageal cancer in the South African population. The role of polymorphisms in alcohol metabolising enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH2) in predisposition of this population to oesophageal cancer is unknown. Alcohol metabolising enzymes exhibit polymorphisms that result in variant alleles with either increased or decreased activity.

METHODS

The role of these polymorphisms in increased risk of oesophageal cancer was investigated in 238 patients and 268 controls from Black and Mixed Ancestry South Africans, using the PCR/RFLP technique.

RESULTS

The ADH3*2/*2 genotype was significantly associated with increased risk for oesophageal cancer amongst Black subjects (odds ratio, 2.19; p=0.004). The low activity ALDH2*2 allele was significantly associated with increased risk for oesophageal cancer amongst the Black subjects (odds ratio, 2.35; p=0.0084).

CONCLUSIONS

It was observed that ADH variants, ADH2*1 and ADH3*2, were associated with increased risk for oesophageal cancer, possibly due to the tolerance of the carriers of these alleles to alcohol consumption compared to those with high activity alleles (ADH2*2 and ADH2*3) which are associated with higher production of the unpleasant acetaldehyde intermediate.

Carcinogenetic impact of ADH1B and ALDH2 genes on squamous cell carcinoma risk of the esophagus with regard to the consumption of alcohol, tobacco and betel quid

The consumption of alcohol, tobacco and betel quid has been found to be an important contributor to esophageal squamous cell carcinoma (ESCC) in Taiwan. The genotoxic effect of the ADH1B and ALDH2 genes modulating an individual's alcohol-metabolizing capacity on ESCC may be linked to drinking behavior, intake pattern and other exogenous factors. To investigate the interplay of these genetic and environmental factors in determining the risk of ESCC, a multicenter case-control study was conducted. Here, 406 patients with pathology-proven ESCC, as well as 656 gender, age and study hospital matched controls were recruited. Genetic polymorphisms of ADH1B and ALDH2 appeared to correlate with the abstinence of alcohol, though not with tobacco and betel quid. Within the same levels of alcohol consumption, carcinoma risks increased along with an increase in the numbers of ADH1B*1 and ALDH2*2 alleles. The inactive ALDH2*1/*2 genotype was found to multiplicatively interact with a low-to-moderate (0.1-30 g/day) and a heavy (>30 g/day) ethanol intake to increase the ESCC risk (the joint aOR = 14.5 and 102.6, respectively). Among low-to-moderate drinkers, a smoking-dependent carcinogenetic effect for the ADH1B*1/*1 and ALDH2*1/*2+*2/*2 genotypes was recognized, with significant risks found in smokers, but not in nonsmokers. Further, a supra-multiplicative combined risk of ESCC for alcohol and tobacco use was identified among carriers of the ADH1B*1/*1 genotype (p for interaction = 0.042). In conclusion, the interplay of the ADH1B and ALDH2 genotypes, in conjunction with a behaved drinking habit and a practiced drinking pattern, along with continued tobacco consumption, plays an important pathogenic role in modulating ESCC risk.

Genetic polymorphisms in cytochrome P4502E1, alcohol and aldehyde dehydrogenases and the risk of esophageal squamous cell carcinoma in Gansu Chinese males

AIM: To evaluate the association between genetic polymorphisms in CYP2E1, ALDH2 and ADH1B and the risk of esophageal squamous cell carcinoma (ESCC) in a high risk area of Gansu Province, in Chinese males.

METHODS: A case-control study was conducted to investigate the genetic polymorphisms of these enzymes (CYP2E1*c1/*c2, ALDH2*1/*2 and ADH1B *1/*1 genotypes). A total of 80 esophageal cancer cases and 480 controls were recruited.

RESULTS: Compared with controls, cases had a greater prevalence of heavier alcohol consumption (53.8% vs 16.2%) and a higher proportion of alcohol drinkers with > 30 drink-years (28.8% vs 13.5%). Heavier alcohol consumption and alcohol drinking with > 30 drink-years increased the risk of ESCC, with ORs (95% CI) of 3.20 (1.32-9.65) and 1.68 (0.96-3.21). CYP2E1 (*c1/*c1), ALDH2 (*1/*2) and ADH1B (*1/*1) genotype frequencies were higher among patients with squamous cell carcinomas, at a level close to statistical significance (P = 0.014; P = 0.094; P = 0.0001 respectively). There were synergistic interactions among alcohol drinking and ALDH2, ADH1B and CYP2E1 genotypes. The risk of the ESCC in moderate-to-heavy drinkers with an inactive ALDH2 encoded by ALDH2*1/*2 as well as ADH1B encoded by ADH1B *1/*1 and CYP2E1 encoded by CYP2E1 *c1/*c1 was higher than that in the never/rare-to-light drinkers with an active ALDH2 (*1/*1 genotype) as well as ADH1B (*1/*2 + *2/*2) and CYP2E1 (*c1/*c2 + *c2/*c2) genotypes, with a statistically significant difference; ORs (95% CI) of 8.58 (3.28-22.68), 27.12 (8.52-70.19) and 7.64 (2.82-11.31) respectively. The risk of the ESCC in moderate-to-heavy drinkers with ALDH2 (*1/*2) combined the ADH1B (*1/*1) genotype or ALDH2 (*1/*2) combined the CYP2E1 (*c1/*c1) genotype leads to synergistic interactions, higher than drinkers with ALDH2 (*1/*1) + ADH1B (*1/*2 + *2/*2), ALDH2 (*1/*1) + CYP2E1 (*c1/*c2 + *c2/*c2) respectively , ORs (95% CI) of 7.46 (3.28-18.32) and 6.82 (1.44-9.76) respectively. Individuals with the ADH1B combined the CYP2E1 genotype showed no synergistic interaction.

CONCLUSION: In our study, we found that alcohol consumption and polymorphisms in the CYP2E1, ADH1B and ALDH2 genes are important risk factors for ESCC, and that there was a synergistic interaction among polymorphisms in the CYP2E1, ALDH2 and ADH1B genes and heavy alcohol drinking, in Chinese males living in Gansu Province, China.

Single-dose ethanol administration downregulates expression of cytochrome p450 2E1 mRNA in aldehyde dehydrogenase 2 knockout mice

The polymorphism of aldehyde dehydrogenase 2 (ALDH2), denoted ALDH2*2, is very common in East Asian origin. Acetaldehyde, an intermediate metabolite of ethanol, is metabolized very slowly in people with ALDH2*2 because the mutant ALDH2 protein lacks the activity of acetaldehyde metabolism. On the other hand, it is well established that one of the cytochrome P450 enzymes, CYP2E1, is an activator of carcinogens (e.g., nitorosamines) and a generator of oxidative stress, and it is shown that CYP2E1 was induced by ethanol via gene transcriptional regulation. In the present study, to examine the consequences of ALDH2 polymorphism on transcriptional regulation of CYP2E1 in liver tissue, Aldh2+/+ and Aldh2-/- mice were orally administered 5 g/kg body weight of ethanol and the levels of CYP2E1 mRNA in liver tissue then analyzed. The level of CYP2E1 mRNA 12h after the ethanol administration tended to be higher than the 0-h group in Aldh2+/+ mice, however, it was significantly lower than the 0-h group in Aldh2-/- mice. These findings suggest that single-dose ethanol administration downregulates the expression of cytochrome p450 2E1 mRNA in the presence of inactive ALDH2.

Genetic polymorphisms of ADH2 and ALDH2 association with esophageal cancer risk in southwest China

AIM: To evaluate the impact of alcohol dehydrogenase 2 (ADH2) and aldehyde dehydrogenase 2 (ALDH2) polymorphisms on esophageal cancer risk.

METHODS: One hundred and ninety-one esophageal cancer patients and 198 healthy controls from Yanting County were enrolled in this study. ADH2 and ALDH2 genotypes were examined by polymerase-chain-reaction with the confronting-two-pair-primer (PCR-CTPP) method. Unconditional logistic regression was used to calculate the odds ratios (OR) and 95% confidence interval (95% CI).

RESULTS: Both ADH2*1 allele and ALDH2*1/*2 allele showed an increased risk of developing esophageal cancer. The adjusted OR (95% CI) for ADH2*1 allele compared with ADH2*2/*2 was 1.65 (95% CI = 1.02-2.68) and 1.67 (95% CI = 1.02-2.72) for ALDH2*1/*2 compared with ALDH2*1/*1. A significant interaction between ALDH2 and drinking was detected regarding esophageal cancer risk, the OR was 1.83 (95% CI = 1.13-2.95). Furthermore, when compared with ADH2*2/*2 and ALDH2*1/*1 carriers, ADH2*1 and ALDH2*2 carriers showed an elevated risk of developing esophageal cancer among non-alcohol drinkers (OR = 2.46, 95% CI = 0.98-6.14), and a significantly elevated risk of developing esophageal cancer among alcohol drinkers among alcohol drinkers (OR = 9.86, 95% CI = 3.10-31.38).

CONCLUSION: ADH2 and ALDH2 genotypes are associated with esophageal cancer risk. ADH2*1 allele and ALDH2*2 allele carriers have a much higher risk of developing esophageal cancer, especially among alcohol drinkers.

Genetic polymorphisms and esophageal cancer risk

The aim of this paper is to review and evaluate, in a comprehensive manner, the published data regarding the contribution of genetic polymorphisms to risk of esophageal cancer, including squamous cell carcinoma (SCC) and adenocarcinoma, in humans. All relevant studies available in MEDLINE and published before February 2007 were identified. Studies carried out in humans and that compared esophageal cancer patients with at least 1 standard control group were considered for analysis. One-hundred studies and 3 meta-analyses were identified. Eighty (80%) studies were conducted in Asian countries, particularly China including Taiwan (60 (60%) studies). The most intensively examined genes were those encoding carcinogen metabolic enzymes. The most widely studied gene was GSTM1 (15 studies), followed by ALDH2 (11 studies). ALDH2, MTHFR C677T, CYP1A1 Ile/Val, CYP1A1MspI, CYP2E1, GSTP1, GSTM1 and GSTT1 were examined by meta-analyses and significant relations were found between ALDH2*1*2 and the CYP1A1 Val allele and increased risk of esophageal cancer. In addition, increased risk of esophageal SCC was consistently associated with the ADH2*1*2 and the p53 codon 72 Pro/Pro genotypes. Cohort studies that simultaneously consider multiple genetic and environmental factors possibly involved in esophageal carcinogenesis are needed to ascertain not only the relative contribution of these factors to tumor development but also the contributions of their putative interactions.

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 1B genotype and fetal alcohol syndrome: a HuGE minireview

Fetal alcohol syndrome (FAS), 1 of the most common developmental disabilities in the United States, occurs at a rate of 0.5-2.0:1000 live births. Animal model, family, and twin studies suggest a genetic component to FAS susceptibility. Alcohol dehydrogenases (ADHs) catalyze the rate-limiting step in alcohol metabolism. Studies of genetic associations with FAS have focused on the alcohol dehydrogenase 1B (ADH1B) gene, comparing mothers and children with the alleles ADH1B*2 or ADH1B*3, associated with faster ethanol metabolism, with those homozygous for ADH1B*1. While most studies have found a protective effect for genotypes containing ADH1B*2 or ADH1B*3, results have been conflicting, and further investigation into the association between the ADH1B genotype and FAS is needed. Whether increased alcohol intake accounts for the elevated risk reported for the ADH1B*1/ADH1B*1 genotype should be addressed, and future studies would benefit from consistent case definitions, enhanced exposure measurements, larger sample sizes, and careful study design.

Pancreatitis: prevalence and risk factors among male veterans in a detoxification program

OBJECTIVES

To determine the prevalence of pancreatitis and associated risk factors among heavy-drinking veterans.

METHODS

At a large Veterans Administration Outpatient Detoxification Program (ODP) that systematically collects risk information, 1409 black and white male veterans with International Classification of Diseases, Ninth Revision codes for alcohol abuse enrolling in the ODP from January 2002 to December 2003 were identified. Among these patients, pancreatitis at any time (before the ODP admission or occurring through June 2005) was identified using International Classification of Diseases, Ninth Revision codes. Cases were verified by chart review. Logistic regression analyses were used for multivariable analyses.

RESULTS

Overall, history of smoking (89.6%) and current or past drug use (90.1%) were very common, whereas intravenous drug use (22.3%) was less so. Although 87 (6.2%) subjects had pancreatitis codes (acute, 50; chronic, 15; both, 22), chart review verified only 42 cases (acute, 29; chronic, 5; both, 8) for a 3% prevalence. Alcohol appeared to be the definite etiology in 39 of these 42 patients. In bivariate analyses, patients with pancreatitis were older, had more substance abuse admissions, reported a significantly heavier current alcohol use, and lower drug dependence (each P < 0.05). In multivariable models, alcoholic pancreatitis was associated positively with age (odds ratio, 1.08; 95% confidence interval, 1.04-1.12) and number of substance abuse admissions (odds ratio, 1.08; 95% confidence interval, 0.995-1.18; P = 0.06).

CONCLUSIONS

In this high-risk population of heavy drinkers, the prevalence of pancreatitis is at least 3%. Our study provides preliminary data regarding potential cofactors for pancreatitis in heavy drinkers.

Genotoxic effects of alcohol in human peripheral lymphocytes modulated by ADH1B and ALDH2 gene polymorphisms

Ethanol is almost totally broken down by oxidative metabolism in vivo. Ethanol per se is considered to be neither carcinogenic, mutagenic nor genotoxic. However, during the metabolic conversion of ethanol to acetaldehyde and acetate, the organism is exposed to both ethanol and acetaldehyde and therefore ethanol is suspected to be co-carcinogenic. The genetic polymorphisms of alcohol dehydrogenase-2 (ADH1B) and acetaldehyde dehydrogenase-2 (ALDH2) influence the metabolism of alcohol. The ADH1B*1/*1 genotype encodes the low-activity form of ADH1B, and ALDH2*1/*2 and ALDH2*2/*2 genotype encode inactive ALDH2. The aim of this study was to test the hypothesis that polymorphisms of the ADH1B and ALDH2 genes are significantly associated with genotoxicity induced by alcohol drinking, measured using the cytokinesis-block micronucleus (CBMN) assay, an established biomarker of genome instability, in peripheral blood lymphocytes of 286 healthy Japanese men. There was a significant trend for the mean micronuclei (MN) frequency in habitual or moderate drinkers without a smoking habit to increase as the numbers of the *1 allele in ADH1B increased (P=0.039 or P=0.029) and the *2 allele in ALDH2 increased (P=0.019 or P=0.037). A logistic regression analysis showed that the number of subjects with MN frequency levels more than median value of MN (3.0) was significantly higher in the subjects with the ADH1B*1 allele as adjusted estimates (OR 2.08, 95% C.I. 1.24-3.48), when the OR for the subjects with the ADH1B*2/*2 genotype was defined as 1.00. The number of subjects with MN frequency levels more than median value of MN was also significantly higher in the subjects with the ALDH2*2 allele as adjusted estimates (OR 1.79, 95% C.I. 1.04-3.11), when the OR for the subjects with the ALDH2*1/*1 genotype was defined as 1.00. The results of this study have identified important novel associations between ADH1B/ALDH2 polymorphisms and genotoxicity in alcohol drinkers.

Lack of aldehyde dehydrogenase ameliorates oxidative stress induced by single-dose ethanol administration in mouse liver

Polymorphism of aldehyde dehydrogenase 2 (ALDH2), denoted ALDH2*2, is far more common in East Asian countries. Acetaldehyde, an intermediate metabolite of ethanol, is metabolized very slowly in people who have ALDH2*2, as the mutated ALDH2 lacks acetaldehyde metabolizing activity. On the other hand, it is well established that metabolism of ethanol causes oxidative stress in liver tissue. To examine the consequences of this polymorphism on ethanol-induced oxidative stress in liver tissue, we conducted a study using Aldh2 knockout mice. Aldh2+/+ and Aldh2-/- mice were orally administered ethanol at a dose of 5g/kg body weight. Levels of malondialdehyde, an indicator of oxidative stress, and glutathione, a key antioxidant, in liver tissue were analyzed 0-24h after administration. Levels of malondialdehyde were significantly lower in Aldh2-/- mice than in Aldh2+/+ mice at 12h after injection, while levels of glutathione were higher in Aldh2-/- mice than in Aldh2+/+ mice at 6 and 12h after injection. Our results suggest that a lack of ALDH ameliorates ethanol-induced oxidative stress in liver tissue.

Genes or environment to determine alcoholic liver disease and non-alcoholic fatty liver disease

While the vast majority of heavy drinkers and individuals with obesity, insulin resistance, and the metabolic syndrome will have steatosis, only a minority will ever develop steatohepatitis, fibrosis, and cirrhosis. Genetic and environmental risk factors for advanced alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) seem likely to include factors that influence the severity of steatosis and oxidative stress, the cytokine milieu, the magnitude of the immune response, and/or the severity of fibrosis. For ALD, the dose and pattern of alcohol intake, along with obesity are the most important environmental factors determining disease risk. For NAFLD, dietary saturated fat and antioxidant intake and small bowel bacterial overgrowth may play a role. Family studies and interethnic variations in susceptibility suggest that genetic factors are important in determining disease risk. For ALD, functional polymorphisms in the alcohol dehydrogenases and aldehyde dehydrogenase alcohol metabolising genes play a role in determining susceptibility in Oriental populations. No genetic associations with advanced NAFLD have been replicated in large studies. Preliminary data suggest that polymorphisms in the genes encoding microsomal triglyceride transfer protein, superoxide dismutase 2, the CD14 endotoxin receptor, TNF-alpha, transforming growth factor-beta, and angiotensinogen may be associated with steatohepatitis and/or fibrosis.

Association of smoking, alcohol drinking and dietary factors with esophageal cancer in high- and low-risk areas of Jiangsu Province, China

AIM: To study the main environmental and lifestyle factors that account for the regional differences in esophageal cancer (EC) risk in low- and high-risk areas of Jiangsu Province, China.

METHODS: Since 2003, a population-based case-control study has been conducted simultaneously in low-risk (Ganyu County) and high-risk (Dafeng County) areas of Jiangsu Province, China. Using identical protocols and pre-tested standardized questionnaire, following written informed consent, eligible subjects were inquired about their detail information on potential determinants of EC, including demographic information, socio-economic status, living conditions, disease history, family cancer history, smoking, alcohol drinking, dietary habits, frequency, amount of food intake, etc. Conditional logistic regression with maximum likelihood estimation was used to obtain Odds ratio (OR) and 95 % confidence interval (95% CI), after adjustment for potential confounders.

RESULTS: In the preliminary analysis of the ongoing study, we recruited 291 pairs of cases and controls in Dafeng and 240 pairs of cases and controls in Ganyu, respectively. In both low-risk and high-risk areas, EC was inversely associated with socio-economic status, such as level of education, past economic status and body mass index. However, this disease was more frequent among those who had a family history of cancer or encountered misfortune in the past 10 years. EC was also more frequent among smokers, alcohol drinkers and fast eaters. Furthermore, there was a geographic variation of the associations between smoking, alcohol drinking and EC risk despite the similar prevalence of these risk factors in both low-risk and high-risk areas. The dose-response relationship of smoking and smoking related variables, such as age of the first smoking, duration and amount were apparent only in high-risk areas. On the contrary, a dose-response relationship on the effect of alcohol drinking on EC was observed only in low-risk areas.

CONCLUSION: The environmental risk factors, together with genetic factors and gene-environmental interactions might be the main reason for this high-risk gradient in Jiangsu Province, China.

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.

Mean Corpuscular Volume, Alcohol Flushing, and the Predicted Risk of Squamous Cell Carcinoma of the Esophagus in Cancer-Free Japanese Men

BACKGROUND

Because some of the causes of increased mean corpuscular volume (MCV) and esophageal squamous cell carcinoma (ESCC), including alcoholism, acetaldehyde exposure, smoking, and poor nutrition are common to both, macrocytosis has been used as a predictor of early ESCC in Japanese alcoholics. We examined whether this was also true in the Japanese general population.

METHODS

This study compared the MCV of 522 cancer-free Japanese men with his risk of ESCC as defined using drinking, smoking, dietary habits and aldehyde dehydrogenase-2 (ALDH2) genotype in a previous case-control study of ESCC involving them as control subjects.

RESULTS

MCV was significantly correlated with ESCC risk predicted by drinking combined with ALDH2 genotype, smoking, or fruit intake. Men at higher risk of ESCC were more frequent in the groups with higher MCV (p < 0.0001 for trend). The replies to a questionnaire about facial flushing in response to alcohol showed that the trend was more prominent in men with current/former flushing, a surrogate marker for inactive ALDH2, than in men with no flushing (p < 0.0001). In comparison with the mean risk of men with MCV < or = 93 fl (lowest quartile), that of current/former flushing men with MCV > or = 99 fl (highest quartile) was 6.35-fold higher, whereas that of never-flushing men with MCV > or = 99 fl was 2.50-fold higher. The sensitivity and specificity of the combination of moderate-to-heavy drinking and either MCV > or = 99 fl or current/former flushing, either 30+ pack-years or MCV > or = 99 fl or either 30+ pack-years or current/former flushing for detection of high-risk persons ranking in the top 10%, was 85% and 84%, 94% and 76%, or 98% and 77%, respectively.

CONCLUSIONS

MCV and alcohol flushing might be used to better select candidates to screen this high-mortality-rate cancer not only in alcoholics but also in nonalcoholic Japanese men.

Relationship between genetic polymorphisms of alcohol and aldehyde dehydrogenases and esophageal squamous cell carcinoma risk in males

AIM: To investigate the association between the genetic polymorphisms of ADH2 and ALDH2, lifetime alcohol consumption and esophageal cancer risk in the Taiwanese men.

METHODS: Between August 2000 and June 2003, 134 pathologically-proven esophageal squamous cell carcinoma male patients and 237 male controls were recruited from Kaohsiung Medical University Hospital and Kaohsiung Veterans General Hospital in southern Taiwan. ADH2 and ALDH2 polymorphisms were genotyped using PCR-RFLP.

RESULTS: Compared to those with ADH2*2/*2, individuals with ADH2*1/*2 and ADH2*1/*1 had 2.28- and 7.14-fold, respectively, increased risk of developing esophageal cancer (95%CI = 1.11-4.68 and 2.76-18.46) after adjusting for alcohol consumption and other covariates. The significant increased risk was also noted among subjects with ALDH2*1/*2 (adjusted OR (AOR) = 5.25, 95%CI = 2.47-11.19), when compared to those with ALDH2*1/*1. The increased risk of esophageal cancer was made greater, when subjects carried both ADH2*1/*1 and ALDH2*1/*2, compared to those with ADH2*1/*2 or ADH2*2/*2 and ALDH2*1/*1 (AOR = 36.79, 95%CI = 9.36-144.65). Furthermore, we found a multiplicative effect of lifetime alcoholic consumption and genotypes (ADH2 and ALDH2) on esophageal cancer risk.

CONCLUSION: Our findings suggest that polymorphisms of ADH2 and ALDH2 can modify the influence of alcoholic consumption on esophageal cancer risk.