Distribution of ADH1B, ALDH2, CYP2E1 *6, and CYP2E1 *7B genotypes in Turkish population

A comprehensive review of cytochrome P450 2E1 for xenobiotic metabolism

Cytochrome P450 2E1 (CYP2E1) plays a vital role in drug-induced hepatotoxicity and cancers (e.g. lung and bladder cancer), since it is responsible for metabolizing a number of medications and environmental toxins to reactive intermediate metabolites. CYP2E1 was recently found to be the highest expressed CYP enzyme in human livers using a proteomics approach, and CYP2E1-related toxicity is strongly associated with its protein level that shows significant inter-individual variability related to ethnicity, age, and sex. Furthermore, the expression of CYP2E1 demonstrates regulation by extensive genetic polymorphism, endogenous hormones, cytokines, xenobiotics, and varying pathological states. Over the past decade, the knowledge of pharmacology, toxicology, and biology about CYP2E1 has grown remarkably, but the research progress has yet to be summarized. This study presents a timely systematic review on CYP2E1's xenobiotic metabolism, genetic polymorphism, and inhibitors, with the focus on their clinical relevance for the efficacy and toxicity of various CYP2E1 substrates. Moreover, several knowledge gaps have been identified towards fully understanding the potential interactions among different CYP2E1 substrates in clinical settings. Through in-depth analyses of these knowns and unknowns, we expect this review will aid in future drug development and improve management of CYP2E1 related clinical toxicity.

Polymorphism study of nine SNPs associated with subjective response to alcohol in Chinese Han, Hui, Tibetan, Mongolian and Uygur populations

Heavy alcohol drinking is a major public health problem, causing a large disease, social and economic burden in societies. Subjective response (SR) to alcohol is an intermediate characteristic of heavy drinking. A variety of candidate genes have been reported to be associated with SR to alcohol. In this study, we investigated nine single nucleotide polymorphisms (SNPs) related to SR to alcohol in healthy individuals from five Chinese ethnic groups, the Han, Hui, Tibetan, Mongolian and Uygur populations, and a total of 584 bloodstain samples were collected. The nine SNPs included four SNPs in alcohol-metabolizing genes (ADH1B, ADH1C, ALDH2 and CYP2E1*5B) and five SNPs in genes of neurobiological pathways (GABRA2, OPRM1, CHRNA3, HYKK and SLC6A4). A SNaPshot analysis method was developed to type these SNPs simultaneously, and all samples were typed successfully. Statistical analyses of the allele frequencies indicated that the frequencies of all SNPs, except for ADH1C, showed varying degrees of difference in the five studied ethnic groups. Tibetans showed the highest frequencies of risk alleles for heavy drinking at most loci. The genetic polymorphic differences found in this study revealed the variation in genetic susceptibility to heavy drinking in the studied populations.

Distinct Prognostic Values of Alcohol Dehydrogenase Family Members for Non-Small Cell Lung Cancer

BACKGROUND Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related death worldwide. The relationships of alcohol dehydrogenase (ADH) enzymes, encoded by the genes ADH1 (1A), ADH1B (ADH2), ADH1C (ADH3), ADH4, ADH5, ADH6, and ADH7, with NSCLC have not been studied. The aim of this study was to explore the associations between NSCLC prognosis and the expression patterns of ADH family members. MATERIAL AND METHODS The online resource Metabolic gEne RApid Visualizer was used to assess the expression patterns of ADH family members in normal and primary lung tumor tissues. The GeneMANIA plugin of Cytoscape software and STRING website were used to evaluate the relationships of the 7 ADH family members at the gene and protein levels. Gene ontology enrichment analysis and KEGG pathway analysis were performed using DAVID. The online website Kaplan-Meier Plotter was used to construct survival curves between NSCLC and ADH isoforms. RESULTS The prognosis of patients with high expression levels of the ADH1B, ADH1C, ADH4, and ADH5 genes was better than those with low expression in adenocarcinoma and all (containing adenocarcinoma and squamous cell cancer) histological types (all P<0.05). Low expression of ADH7 was associated with a better prognosis in patients with both the adenocarcinoma and squamous cell cancer histological types (P=9e-05). Moreover, expression of ADH family members was associated with smoking status, clinical stage, and chemotherapy status. CONCLUSIONS ADH1B, ADH1C, ADH4, ADH5, and ADH7 appear to be useful biomarkers for the prognosis of NSCLC patients.

Genetic Polymorphisms of the Mitochondrial Aldehyde Dehydrogenase ALDH2 Gene in a Large Ethnic Hakka Population in Southern China

Background

Human mitochondrial aldehyde dehydrogenase 2 (ALDH2) plays a critical role in the detoxification of the ethanol metabolite acetaldehyde. The ALDH2*2 (rs671) gene variant is mainly absent among Europeans but is prevalent in populations in East Asia. The aim of this study was to investigate ALDH2*2 mutant alleles and genotype frequencies in the Hakka population of China.

Material/Methods

Between January 2016 and June 2017, 7,966 unrelated individuals were recruited into the study from the Hakka ethnic population residing in the Meizhou area of Guangdong Province, China, who provided venous blood samples. Genotyping of ALDH2 genotypes were determined using a gene chip platform and confirmed by DNA sequencing.

Results

In the 7,966 individuals from the Hakka population of China in this study, the frequencies of the ALDH2 genotypes *1/*1, *1/*2 and *2/*2 were 52.03%, 39.67%, and 8.30%, respectively; 47.97% of the individuals were found to carry the ALDH2*2 genotype, which was associated with a deficiency in the aldehyde dehydrogenase (ALDH2) enzyme activity. The frequency of the ALDH2*2 allele was lower than that previously reported in the Japanese population but higher than that reported in other Oriental populations.

Conclusions

The findings of this study have provided new information on the ALDH2 gene polymorphisms in the Hakka ethnic population residing in the Meizhou area of Guangdong Province, China, including an understanding of the origin of the atypical ALDH2*2 allele. Also, the study findings may be relevant to the primary care of patients in China.

Effect of alcohol dehydrogenase-1B and -7 polymorphisms on blood ethanol and acetaldehyde concentrations in healthy subjects with a history of moderate alcohol consumption

This study aims to evaluate the effect of ADH1B and ADH7 genotypes on blood acetaldehyde and ethanol levels after alcohol ingestion, and to measure the genotoxic effect of smoking and ethanol on the buccal cells, also controlling for ADH variants. We recruited healthy Italian subjects with at least a moderate history of alcohol consumption. All subjects were given an alcoholic drink of 0.4 g ethanol /kg of body weight. Blood venous samples were collected at baseline, and 30, 60, 90, and 120 minutes after ingestion. Buccal cells were collected before ethanol ingestion. Sixty subjects were enrolled in the study. Individuals with the ADH1B GG genotype had median ethanol levels of 5.0mM (IQR 3.4-7.2), and those with the ADH1B GT/TT genotype had 4.7mM (IQR 4.2-4.8). Corresponding acetaldehyde levels were 1.5μM (IQR 0.7-2.6) for ADH1B GG genotype and 1.6μM (IQR 1.5-1.7) for ADH1B CG/GG genotype. Individuals with the ADH7 CC genotype had median ethanol levels of 5.0mM (IQR 3.3-7.2), while 5.0mM (IQR 4.7-5.6) was in those with the ADH7 CG/GG genotype. Corresponding acetaldehyde levels were 1.5 μM (IQR 0.7-2.6) for ADH7 CC genotype and 1.5 μM (IQR 1.4-1.6) for ADH7 CG/GG genotypes. A non-significant increase in the frequency of karyolitic and pyknotic cells was found in the group of heavy drinkers and current smokers, when compared to the moderate drinkers and the non-smokers. Our study does not support the hypothesis that ADH1B and ADH7 genotypes affect blood ethanol and acetaldehyde concentration.

Polymorphisms in ADH1B and ALDH2 genes associated with the increased risk of gastric cancer in West Bengal, India

BACKGROUND

Gastric cancer (GC) is one of the most frequently diagnosed digestive tract cancers and carries a high risk of mortality. Acetaldehyde (AA), a carcinogenic intermediate of ethanol metabolism contributes to the risk of GC. The accumulation of AA largely depends on the activity of the major metabolic enzymes, alcohol dehydrogenase and aldehyde dehydrogenase encoded by the ADH (ADH1 gene cluster: ADH1A, ADH1B and ADH1C) and ALDH2 genes, respectively. This study aimed to evaluate the association between genetic variants in these genes and GC risk in West Bengal, India.

METHODS

We enrolled 105 GC patients (cases), and their corresponding sex, age and ethnicity was matched to 108 normal individuals (controls). Genotyping for ADH1A (rs1230025), ADH1B (rs3811802, rs1229982, rs1229984, rs6413413, rs4147536, rs2066702 and rs17033), ADH1C (rs698) and ALDH2 (rs886205, rs968529, rs16941667 and rs671) was performed using DNA sequencing and RFLP.

RESULTS

Genotype and allele frequency analysis of these SNPs revealed that G allele of rs17033 is a risk allele (A vs G: OR = 3.67, 95% CI = 1.54-8.75, p = 0.002) for GC. Significant association was also observed between rs671 and incidence of GC (p = 0.003). Moreover, smokers having the Lys allele of rs671 had a 7-fold increased risk of acquiring the disease (OR = 7.58, 95% CI = 1.34-42.78, p = 0.009).

CONCLUSION

In conclusion, rs17033 of ADH1B and rs671 of ALDH2 SNPs were associated with GC risk and smoking habit may further modify the effect of rs671. Conversely, rs4147536 of ADH1B might have a protective role in our study population. Additional studies with a larger patient population are needed to confirm our results.

Lipids and Oxidative Stress Associated with Ethanol-Induced Neurological Damage

The excessive intake of alcohol is a serious public health problem, especially given the severe damage provoked by chronic or prenatal exposure to alcohol that affects many physiological processes, such as memory, motor function, and cognitive abilities. This damage is related to the ethanol oxidation in the brain. The metabolism of ethanol to acetaldehyde and then to acetate is associated with the production of reactive oxygen species that accentuate the oxidative state of cells. This metabolism of ethanol can induce the oxidation of the fatty acids in phospholipids, and the bioactive aldehydes produced are known to be associated with neurotoxicity and neurodegeneration. As such, here we will review the role of lipids in the neuronal damage induced by ethanol-related oxidative stress and the role that lipids play in the related compensatory or defense mechanisms.

Significant genotype difference in the CYP2E1 PstI polymorphism of indigenous groups in Sabah, Malaysia with Asian and non-Asian populations

CYP2E1 PstI polymorphism G-1259C (rs3813867) genotype distributions vary significantly among different populations and are associated with both diseases, like cancer, and adverse drug effects. To date, there have been limited genotype distributions and allele frequencies of this polymorphism reported in the three major indigenous ethnic groups (KadazanDusun, Bajau, and Rungus) in Sabah, also known as North Borneo. The aim of this study was to investigate the genotype distributions and allele frequencies of the CYP2E1 PstI polymorphism G-1259C in these three major indigenous peoples in Sabah. A total of 640 healthy individuals from the three dominant indigenous groups were recruited for this study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) at G-1259C polymorphic site of CYP2E1 gene was performed using the Pst I restriction enzyme. Fragments were analyzed using agarose gel electrophoresis and confirmed by direct sequencing. Overall, the allele frequencies were 90.3% for c1 allele and 9.7% for c2 allele. The genotype frequencies for c1/c1, c1/c2 and c2/c2 were observed as 80.9%, 18.8%, and 0.3%, respectively. A highly statistical significant difference (p<0.001) was observed in the genotype distributions between indigenous groups in Sabah with all Asian and non-Asian populations. However, among these three indigenous groups, there was no statistical significant difference (p>0.001) in their genotype distributions. The three major indigenous ethnic groups in Sabah show unique genotype distributions when compared with other populations. This finding indicates the importance of establishing the genotype distributions of CYP2E1 PstI polymorphism in the indigenous populations.

Genetic polymorphisms of ADH1B, ADH1C and ALDH2 in Turkish alcoholics: lack of association with alcoholism and alcoholic cirrhosis

No data exists regarding the alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) gene polymorphisms in Turkish alcoholic cirrhotics. We studied the polymorphisms of ADH1B, ADH1C and ALDH2 genes in alcoholic cirrhotics and compared the results with non-cirrhotic alcoholics and healthy volunteers. Overall, 237 subjects were included for the study: 156 alcoholic patients (78 cirrhotics, 78 non-cirrhotic alcoholics) and 81 healthy volunteers. Three different single-nucleotide-polymorphism genotyping methods were used. ADH1C genotyping was performed using a polymerase chain reaction-restriction fragment length polymorphism method. The identified ADH1C genotypes were named according to the presence or absence of the enzyme restriction sites. ADH1B (Arg47Hys) genotyping was performed using the allele specific primer extension method, and ALDH2 (Glu487Lys) genotyping was performed by a multiplex polymerase chain reaction using two allele-specific primer pairs. For ADH1B, the frequency of allele *1 in the cirrhotics, non-cirrhotic alcoholics and healthy volunteers was 97.4%, 94.9% and 99.4%, respectively. For ADH1C, the frequency of allele *1 in the cirrhotics, non-cirrhotic alcoholics and healthy volunteers was 47%, 36.3% and 45%, respectively. There was no statistical difference between the groups for ADH1B and ADH1C (p&gt;0.05). All alcoholic and non-alcoholic subjects (100%) had the allele *1 for ALDH2. The obtained results for ADH1B, ADH1C, and ALDH gene polymorphisms in the present study are similar to the results of Caucasian studies. ADH1B and ADH1C genetic variations are not related to the development of alcoholism or susceptibility to alcoholic cirrhosis. ALDH2 gene has no genetic variation in the Turkish population.

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.

Genetic alcohol sensitivity regulated by ALDH2 and ADH1B polymorphisms as indicator of mental disorders in Japanese employees

AIMS

Alcohol-related disorders (ARD) have been shown to be accompanied by a variety of other comorbid mental disorders. This study evaluated the associations between a variety of mental disorders and genetic alcohol sensitivity.

METHODS

A total of 1944 Japanese workers were interviewed regarding their mental disorders by the Mini-International Neuropsychiatric Interview (M.I.N.I.). We investigated the relationship of ADH1B rs1229984 and ALDH2 rs671 polymorphisms' combination with mental disorder risks. Logistic regression analysis was used to evaluate the associations between those polymorphisms and mental disorders, adjusting for sex, age, and job rank.

RESULTS

The degree of alcohol sensitivity was classified into five groups according to the combination of ADH1B and ALDH2 genotypes (Group I-V in order starting from the lowest alcohol sensitivity). Those with ALDH2 *1/*1 and ADH1B *1/*1 or with ALDH2 *1/*1 and ADH1B *1/*2,*2/*2 (low sensitivity) were significantly or nearly significantly associated with an increased risk of ARD compared with those with ALDH2 *1/*2 and ADH1B *1/*2,*2/*2 as a reference. Those with ALDH2 *1/*1 and ADH1B *1/*1 were also likely to be at an increased risk of any mental disorder except ARD, as well as disorders without comorbid ARD. This tendency was more apparent among women (OR 11.94, 95% CI 0.73-195.63) and non-drinkers (OR 5.43, 95% CI 1.05-28.23).

CONCLUSION

The genotype combination of ALDH2 *1/*1 and ADH1B *1/*1 is significantly associated with an increased risk of any mental disorder, especially ARD. Non-drinkers or women with ALDH2 *1/*1 and ADH1B *1/*1 are likely to suffer from any mental disorder except ARD.

Single nucleotide polymorphism at alcohol dehydrogenase-1B is associated with risk of esophageal squamous cell carcinoma

Background

Esophageal squamous incidence in many developed countries has increased dramatically over last decades, while the underlying mechanism of the biogenesis of ES was still unknown.

Methods

Here, we investigate 1001 subjects with esophageal cancer recruited from the affiliated hospital of Shanghai Jiao Tong University from Jan. 1, 2001 to Feb. 2, 2004. Single nucleotide polymorphism (SNP) of alcohol dehydrogenase-1B (ADH1B) was performed, and the recombinant plasimd containing ADH1B was constructed. Then, the ADH1B was purified and the enzymatic activity was assayed according to the methodology of Quayle. Furthermore, the effect of ADH1B on proliferation of human esophageal squamous cell lines was determined and the underlying mechanism of ADH1B was investigated.

Results

Logistic regression analyses revealed that subjects carrying the GG variant homozygote had a significant 2.81-fold (adjusted OR = 2.81; 95% CI = 2.18-3.62) increased risk of esophageal cancer. We found that SNP of ADH1B (GG) significantly promotes cell proliferation in ESGG. ADH1B (GG) could down-regulate endogenous ADH1B expression at posttranscriptional level. Moreover, re-expression of ADH1B in cells transfected with ADH1B (AA) significantly inhibits cell proliferation.

Conclusions

Our data implied that ADH1B (GG) could promote cell proliferation in human ESGG through regulating the enzyme activity of ADH1B. Therefore, we propose that ADH1B might be used as a therapeutic agent for human ESGG.

Toxicogenetic profile and cancer risk in Lebanese

An increasing number of genetic polymorphisms in drug-metabolizing enzymes (DME) were identified among different ethnic groups. Some of these polymorphisms are associated with an increased cancer risk, while others remain equivocal. However, there is sufficient evidence that these associations become significant in populations overexposed to environmental carcinogens. Hence, genetic differences in expression activity of both Phase I and Phase II enzymes may affect cancer risk in exposed populations. In Lebanon, there has been a marked rise in reported cancer incidence since the 1990s. There are also indicators of exposure to unusually high levels of environmental pollutants and carcinogens in the country. This review considers this high cancer incidence by exploring a potential gene-environment model based on available DME polymorphism prevalence, and their impact on bladder, colorectal, prostate, breast, and lung cancer in the Lebanese population. The examined DME include glutathione S-transferases (GST), N-acetyltransferases (NAT), and cytochromes P-450 (CYP). Data suggest that these DME influence bladder cancer risk in the Lebanese population. Evidence indicates that identification of a gene-environment interaction model may help in defining future research priorities and preventive cancer control strategies in this country, particularly for breast and lung cancer.

Large-scale, ion-current-based proteomics investigation of bronchoalveolar lavage fluid in chronic obstructive pulmonary disease patients

Proteomic analysis of bronchoalveolar lavage fluid (BALF) in chronic obstructive pulmonary disease (COPD) patients may provide new biomarkers and deeper understanding of the disease mechanisms but remains challenging. Here we describe an ion-current-based strategy for comparative analysis of BALF proteomes from patients with moderate and stable COPD versus healthy controls. The strategy includes an efficient preparation procedure providing quantitative recovery and a nano-LC/MS analysis with a long, heated column. Under optimized conditions, high efficiency and reproducibility were achieved for each step, enabling a "20-plex" comparison of clinical subjects (n = 10/group). Without depletion/fractionation, a total of 423 unique protein groups were quantified under stringent criteria with at least two quantifiable peptides. Seventy-six proteins were determined as significantly altered in COPD, which represent a diversity of biological processes such as alcohol metabolic process, gluconeogenesis/glycolysis, inflammatory response, proteolysis, and oxidation reduction. Interestingly, altered alcohol metabolism responding to oxidant stress is a novel observation in COPD. The prominently elevated key enzymes involved in alcohol metabolism (e.g., ADH1B, ALDH2, and ALDH3A1) may provide a reasonable explanation for a bewildering observation in COPD patients known for decades: the underestimation of the blood alcohol concentrations through breath tests. These discoveries could provide new insights for identifying novel biomarkers and pathological mediators in clinical studies.

Genetic polymorphisms of CYP2E1, GST, and NAT2 enzymes are not associated with risk of breast cancer in a sample of Lebanese women

Changes in the activity of drug metabolizing enzymes (DMEs) are potentially associated with cancer risk. This relationship is attributed to their involvement in the bioactivation of multiple procarcinogens or the metabolism of multiple substrates including an array of xenobiotics and environmental carcinogens. 326 Lebanese women of whom 99 were cancer free (controls) and 227 were diagnosed with breast cancer (cases) were included. Blood for DNA was collected and medical charts were reviewed. Three genotyping methods were employed including: (1) restriction fragment length polymorphism (RFLP) for CYP2E1*5B, CYP2E1*6, NAT2*5 and NAT2*6; (2) gel electrophoresis for GSTM1 and GSTT1; and (3) real-time PCR for GSTP1 Ile/Val polymorphism. We analyzed the relationship between genetic susceptibilities in selected xenobiotic metabolizing genes and breast cancer risk. Allele frequencies were fairly similar to previously reported values from neighboring populations with relevant migration routes. There were no statistically significant differences in the distribution of variant carcinogen metabolizing genes between cases and controls even after adjusting for age at diagnosis, menopausal status, smoking, and alcohol intake. Despite its limitations, this is the first study that assesses the role of genetic polymorphisms in DMEs with breast cancer in a sample of Lebanese women. Further studies are needed to determine the genetic predisposition and gene-environment interactions of breast cancer in this population.

Polymorphisms in the CYP2E1 and GSTM1 genes as possible protection factors for leprosy patients

Background

The CYP2E1 and GSTM1 genes encode metabolic enzymes that have key functions in drug modification and elimination.

Methodology/Principal Findings

We investigated the possible effects of CYP2E1 and GSTM1 polymorphisms in 71 leprosy patients and in 110 individuals from the general population. The GSTM1*0 null allele and INDEL CYP2E1*1D mutant genotypes were analyzed by conventional PCR, while CYP2E1 SNPs (1053C>T, 1293G>C and 7632T>A) were determined by RT-PCR. In leprosy patients, the GSTM1*0 and CYP2E1*5 alleles and the combined alleles GSTM1*0/CYP2E1*6 and GSTM1*0/CYP2E1*5 were significantly related to a baciloscopic index (BI) (BI<3), while the CYP2E1*6 allele was related to a better clinical evolution in the leprosy spectrum.

Conclusions/Significance

Therefore, GSTM1*0, CYP2E1*5 and CYP2E1*6 may be possible protection factors for leprosy patients.

A variant allele of ADH1B and ALDH2, is associated with the risk of esophageal cancer

Alcoholic beverages are causally related to esophageal cancer. The genetic polymorphisms of the alcohol-metabolizing enzymes ADH1B rs1229984 and ALDH2 rs671 may modulate individual differences in alcohol-oxidizing capability. A case-control study was conducted to evaluate the genetic effects of these two functional single nucleotide polymorphisms (SNPs) on the development of esophageal cancer. A total of 380 esophageal squamous cell carcinoma cases and 380 controls were recruited. Genotypes were determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Variant alleles of the functional polymorphism ADH1B rs1229984 SNP were associated with an increased risk of esophageal cancer [adjusted odds ratio (OR)=2.39, 95% confidence interval (CI)=1.42-4.03 for ADH1B rs1229984 GG vs. AA]. There was a borderline-significantly decreased risk between the ALDH2 rs671 genotype and esophageal cancer (adjusted OR=0.47, 95% CI=0.22-1.00 for ALDH2 rs671 AA vs. GG). Stratified analyses indicated that both of these effects were more evident among male, younger subjects and smokers. In conclusion, the functional polymorphisms ADH1B rs1229984 and ALDH2 rs671 may contribute to susceptibility to esophageal cancer, particularly among male, younger subjects and smokers.