Genetic polymorphism of human liver alcohol and aldehyde dehydrogenases, and their relationship to alcohol metabolism and alcoholism

HPV, KRAS mutations, alcohol consumption and tobacco smoking effects on esophageal squamous-cell carcinoma carcinogenesis

Esophageal squamous-cell carcinoma (ESCC) is an invasive neoplastic disease generally associated with poor survival rates. The incidence of ESCC is characterized by marked geographic variation, with highest rates noted in developing Southeastern African, Central and Eastern Asian countries. In the developed Western European and North American regions where there is a low disease incidence, heavy alcohol and cigarette consumption constitute major risk factors. The toxic effects of both these risk factors cause chronic irritation and inflammation of the esophageal mucosa, while at the cellular level they further confer mutagenic effects by the activation of oncogenes (e.g., RAS mutations), inhibition of tumor-suppressor genes, and profound DNA damage. Viral infections, particularly with human papillomavirus, may activate specific antiapoptotic, proliferative and malignant cellular responses that may be intensified in combination with the effects of alcohol and tobacco. In countries with a high ESCC incidence, low socioeconomic status and an inadequate diet of poorly preserved food are combined with basic nutritional deficiencies and inadequate medical treatment. These conditions are favorable to the above-mentioned risk factors implicated in ESCC development, which may be present and/or habitually used in certain populations. New perspectives in epidemiological studies of ESCC development and its risk factors allow genome-wide research involving specific environments and habits. Such research should consist of adequately large and representative samples, should use newly designed informative genetic markers, and apply genomic variation analysis of the functional transcripts involved in malignant cell cycle regulation and neoplastic transformation in the multi-step process of ESCC carcinogenesis.

Impact of alcohol dehydrogenase-aldehyde dehydrogenase polymorphism on clinical outcome in patients with hypopharyngeal cancer

BACKGROUND

The purpose of this research was to investigate the association between alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) polymorphisms and hypopharyngeal squamous cell carcinoma (SCC) survival.

METHODS

We genotyped ADH1B (rs1229984) and ALDH2 (rs671) single nucleotide polymorphisms (SNPs) in 85 Japanese male patients with hypopharyngeal SCC. The independent prognostic values of ADH1B-ALDH2 genotypes were analyzed by univariate and multivariate proportional hazard Cox regression, taking well-known clinical risk factors into account.

RESULTS

Heavy drinkers with ALDH2*2 allele resulted in significantly worse overall survival (OS; P = .028) and disease-free survival (DFS; P = .029) compared with other patients. Heavy drinkers with ALDH2*2 allele remained statistically significant in multivariate analysis for OS and DFS, indicating independent poor prognostic factor (hazard ratio [HR] 2.251; 95% confidence interval [CI] 1.018-4.975 and HR 2.261; 95% CI 1.021-5.006, respectively).

CONCLUSION

We conclude that heavy drinkers with the ALDH2*2 allele are associated with poor outcome in hypopharyngeal SCC.

Modification of the Associations of Alcohol Intake With Serum Low-Density Lipoprotein Cholesterol and Triglycerides by ALDH2 and ADH1B Polymorphisms in Japanese Men

Background

Although beneficial associations have been reported between moderate alcohol intake and the serum lipid profile, it is unclear whether polymorphisms in alcohol-metabolizing enzymes can modify these associations. Here, we assessed the effects of ADH1B His48Arg (rs1229984), ALDH2 Glu504Lys (rs671), and their combination on these associations. Furthermore, we examined if the findings for ALDH2 could be replicated.

Methods

We categorized 889 male participants in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study into two groups based on presence or absence of minor allele(s) or four groups based on genotype combinations. We performed regression analyses of serum lipid concentrations on alcohol intake, with multivariable adjustment. The replication study was conducted among 2,562 men in the Shizuoka part of the J-MICC Study.

Results

The ALDH2 Glu/Lys or Lys/Lys groups showed significant decreases in serum low-density lipoprotein (LDL) cholesterol with increasing alcohol consumption; the coefficient per intake increase of 10 g/day was −2.49 mg/dL (95% confidence interval [CI], −3.85 to −1.13), and a significant interaction with the polymorphism was confirmed (P for interaction = 0.006). This inverse correlation was more evident among the ADH1B His/His + ALDH2 Glu/Lys or Lys/Lys groups (−3.24 mg/dL, 95% CI, −5.03 to −1.45). Serum triglycerides were positively associated with alcohol consumption in the ADH1B His/His group (P for interaction = 0.020). The stronger association between serum LDL cholesterol and alcohol consumption in the ALDH2 Glu/Lys or Lys/Lys groups was replicated.

Conclusions

The ALDH2 Glu504Lys polymorphism can modify the association between alcohol intake and serum LDL cholesterol in Japanese men.

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.

Alcohol metabolism and oesophageal cancer: a systematic review of the evidence

Alcohol is a major risk factor for oesophageal squamous cell carcinoma (OSCC), the most prevalent histological subtype of oesophageal cancer (OC) worldwide. The metabolism of alcohol is regulated by specific enzymes whose activity and expression is influenced by genetic polymorphisms. We conducted a systematic review of current epidemiological evidence of the relationship between alcohol intake and OC risk, including the role of tobacco smoking and functional polymorphisms of alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs). Potential biological mechanisms underlying oesophageal carcinogenesis are also discussed. Frequency and intensity of alcohol intake have been consistently associated with an increased risk of OSCC in regions with low and high incidence of the disease. The highest risk was reported among tobacco smokers, whereas the association between alcohol and OSCC risk was weak in the absence of tobacco use. The ADH1B, ADH1C and ALDH2 gene polymorphisms influence the risk of OSCC through modulation of acetaldehyde metabolism and propensity to alcohol intake. These functional variants may be suitable proxies of alcohol exposure for use in Mendelian randomization studies if complemented by reported alcohol intake data. Recent epidemiological and experimental studies investigating the role of alcohol consumption in OC development have implicated the microbiome as a new promising avenue for research, which entail novel potential mechanisms of alcohol-related oesophageal carcinogenesis. Microbial communities associated with alcohol consumption might be used as biomarkers to raise the potential of intervening among susceptible individuals.

Investigating the Association between Alcohol and Risk of Head and Neck Cancer in Taiwan

Although alcohol is an established risk factor of head and neck cancer (HNC), insufficiencies exist in the literature in several aspects. We analyzed detailed alcohol consumption data (amount and type of alcoholic beverage) of 811 HNC patients and 940 controls to evaluate the association between alcohol and HNC by HNC sites and by genotypes of ADH1B and ALDH2. Alcohol was associated with an increased HNC risk in a dose-response relationship, with the highest risk observed for hypopharyngeal cancer, followed by oropharyngeal and laryngeal cancers. Liquor showed a stronger positive association with HNC than beer and wine. The highest HNC risk occurred in individuals with the slow ADH1B and slow/non-functional ALDH2 genotype combination. In our study population, 21.8% of HNCs, 55.7% of oropharyngeal cancers, and 89.1% of hypopharyngeal cancers could be attributed to alcohol. Alcohol accounted for 47.3% of HNCs among individuals with the slow ADH1B and slow/non-functional ALDH2 genotype combination. The HNC risk associated with alcohol became comparable to that of never/occasional drinkers after ten or more years of cessation from regular alcohol drinking. In conclusion, alcohol use is associated with an increased HNC risk, particularly for individuals with slow ethanol metabolism. HNC incidence may be reduced by alcohol cessation.

Heavy alcohol drinking downregulates ALDH2 gene expression but heavy smoking up-regulates SOD2 gene expression in head and neck squamous cell carcinoma

BACKGROUND

This study aims to determine the relationship between expression levels of ALDH2 and SOD2 genes and clinical parameters such as alcohol drinking, tobacco smoking, primary site of HNSCC, and human papilloma virus (HPV) state.

METHODS

Gene expression data were obtained from gene expression omnibus (GEO accession number: GSE65858). Clinical data (N = 270) including survival result, gender, age, TNM stage, primary site of HNSCC, HPV status, alcohol drinking, and tobacco smoking habit were analyzed according to gene expression pattern.

RESULTS

ALDH2 gene was expressed in low levels in patients with heavy alcohol consumption. It was expressed in high (p = 0.01) levels in patients with no or light alcohol consumption. ALDH2 gene was also expressed in low levels in patients with oral cavity cancers or hypopharynx cancers. However, ALDH2 gene was expressed in high (p = 0.03) levels in patients with oropharyngeal cancers or laryngeal cancers. HPV-positive patients were found to have high (p = 0.02) expression levels of ALDH2. SOD2 gene was expressed in high (p = 0.005) levels in patients who had greater mean pack-year of tobacco smoking. Based on log rank test, the group of patients with high expression of ALDH2 showed better (p = 0.002) clinical results than those with low expression of ALDH2. Difference of survival results between ALDH2 high-expressed group and ALDH2 low-expressed group was validated in another cohort (GSE39368, N = 138).

CONCLUSIONS

Heavy alcohol drinking downregulates ALDH2 gene expression level. Heavy smoking up-regulates SOD2 gene expression level in patients with head and neck squamous cell carcinoma. The group of patients with low expression levels of ALDH2 showed significantly poorer survival results compared to those with high expression levels of ALDH2.

Alcohol Consumption and Lung Cancer According to Ile349Val Polymorphism in ADH3 Gene: Beyond the Tobacco Smoking Effect

Objectives: Smoking is the leading cause of lung cancer. However, several studies have suggested other factors such as alcohol consumption could also play a role through polymorphisms associated with alcohol metabolism. We investigated the association between alcohol consumption and lung cancer according to the Ile349Val polymorphism in the alcohol dehydrogenase 3 ADH3 gene. Methods: We carried out a hospital-based case-control study, a total of 402 incident cases of lung cancer and 383 controls were genotyped for the Ile349Val polymorphism by polymerase chain reaction combined with restriction fragment length polymorphism. Alcohol consumption and other variables were measured using questionnaires in personal interviews. We used multiple logistic regressions to estimate adjusted odd ratios using and 95% confidence intervals. Results: In multivariate analysis, an increased risk of lung cancer was observed for the highest category of alcohol consumption (≥30 g/day), although it does not reach statistical significance (OR=1.60, 95% CI: 0.91-2.83). Besides, an increased risk of lung cancer was observed in the highest category of alcohol consumption for the Ile/Val genotype compared with the Ile/Ile genotype (OR=2.35, 95% CI: 1.04-5.33). Conclusions: This study suggests that beyond smoking consumption, a high consumption of alcohol might increase the risk of lung cancer. No clear association was found between alcohol consumption and lung cancer according to the Ile349Val polymorphism in ADH3 gene.

Establishment of a Quick and Highly Accurate Breath Test for ALDH2 Genotyping

Objectives:

Acetaldehyde, the first metabolite of ethanol, is a definite carcinogen for the esophagus, head, and neck; and aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that catalyzes the metabolism of acetaldehyde. The ALDH2 genotype exists as ALDH2*1/*1 (active ALDH2), ALDH2*1/*2 (heterozygous inactive ALDH2), and ALDH2*2/*2 (homozygous inactive ALDH2). Many epidemiological studies have reported that ALDH2*2 carriers are at high risk for esophageal or head and neck squamous cell carcinomas by habitual drinking. Therefore, identification of ALDH2*2 carriers would be helpful for the prevention of those cancers, but there have been no methods suitable for mass screening to identify these individuals.

Methods:

One hundred and eleven healthy volunteers (ALDH2*1/*1 carriers: 53; ALDH2*1/*2 carriers: 48; and ALDH2*2/*2 carriers: 10) were recruited. Breath samples were collected after drinking 100 ml of 0.5% ethanol using specially designed gas bags, and breath ethanol and acetaldehyde levels were measured by semiconductor gas chromatography.

Results:

The median (range) breath acetaldehyde levels at 1 min after alcohol ingestion were 96.1 (18.1–399.0) parts per billion (p.p.b.) for the ALDH2*1/*1 genotype, 333.5 (78.4–1218.4) p.p.b. for the ALDH2*1/*2 genotype, and 537.1 (213.2–1353.8) p.p.b. for the ALDH2*2/*2 genotype. The breath acetaldehyde levels in ALDH2*2 carriers were significantly higher than for the ALDH2*1/*1 genotype. Notably, the ratio of breath acetaldehyde level-to-breath ethanol level could identify carriers of the ALDH2*2 allele very accurately (whole accuracy; 96.4%).

Conclusions:

Our novel breath test is a useful tool for identifying ALDH2*2 carriers, who are at high risk for esophageal and head and neck cancers.

Independent effects of ADH1B and ALDH2 common dysfunctional variants on gout risk

Gout is caused by hyperuricemia, with alcohol consumption being an established risk factor. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are crucial enzymes for alcohol metabolism. We recently performed a genome-wide association study of gout and a subsequent fine-mapping study which identified rs671 of ALDH2 as a gout locus. However, the association between gout and common variants of ADH1B has hitherto remained unreported, prompting us to investigate the association between gout and common dysfunctional variants of ADH1B (rs1229984) and ALDH2 (rs671). We used 1,048 clinically defined gout cases and 1,334 controls of Japanese male. The "His carrier" (His/His or His/Arg) of rs1229984 (His48Arg) of ADH1B significantly increased gout risk (P = 4.3 × 10^-4, odds ratio = 1.76), as did the "non-Lys carrier (Glu/Glu)" of rs671 (Glu504Lys) of ALDH2. Furthermore, common variants of ADH1B and ALDH2 are independently associated with gout. Our findings likewise suggest that genotyping these variants can be useful for the evaluation of gout risk.

Alcoholic hepatitis: current trends in management

PURPOSE OF REVIEW

Alcohol consumption is increasing globally, as are complications of alcohol-related liver disease, including the most severe manifestation, alcoholic hepatitis. Despite the increased prevalence, many patients hospitalized with alcoholic hepatitis are either not diagnosed or inadequately treated leading to significant morbidity and high mortality rates. The purpose of this review is to discuss current challenges in the diagnosis and management of this frequently fatal condition.

RECENT FINDINGS

Recent studies and meta-analyses have improved our understanding of both the evaluation and treatment of alcoholic hepatitis including the diagnostic criteria, appropriate use of glucocorticoids and other therapeutic modalities including novel disease-specific therapeutic agents and indications for considering liver transplantation.

SUMMARY

Glucocorticoid therapy and enteral nutrition represent the best options for reducing short-term mortality in patients with the severe form of acute alcoholic hepatitis. The efficacy of other medications such as pentoxifylline as currently used does not support a role for use outside clinical trials. While the current management options for alcoholic hepatitis remain insufficient, improvements in diagnosis, determining prognosis and severity and the potential role of novel treatments provides encouragement that outcomes from this devastating condition will improve.

ALDH2 Glu504Lys Confers Susceptibility to Schizophrenia and Impacts Hippocampal-Prefrontal Functional Connectivity

Although previous evidence suggested that ALDH2 is a candidate gene for schizophrenia, the association and underlying mechanisms have never been investigated. Therefore, we investigated ALDH2 as a susceptibility gene for schizophrenia and explored the effect of its polymorphisms on brain functions. In the discovery stage, we detected a positive association between a dominant-negative mutant, Glu504Lys, and schizophrenia (P= 8.01E-5, OR = 1.34, 95% CI = 1.16-1.55). This association was confirmed in the validation stage (P= 3.48E-6, OR = 1.28, 95% CI = 1.15-1.42). The combined P reached a genome-wide significance (Pcombined= 1.32E-9, OR = 1.30, 95% CI = 1.20-1.42). To investigate the neural mechanism linking Glu504Lys to schizophrenia, we calculated the functional connectivity (FC) and applied an imaging genetics strategy using resting-state fMRI data. The imaging analysis revealed a significant interaction of diagnostic group by genotype for FC between the left hippocampus and the prefrontal cortex. In the Glu homozygotes, hippocampal-prefrontal FC correlated inversely with memory performance in the healthy controls and with the PANSS negative score in the schizophrenia patients. Our results supported a role for ALDH2 in the pathophysiology of schizophrenia. Moreover, variation at Glu504Lys disrupts hippocampal-prefrontal FC, which might be the neural mechanism linking it to the disease.

Role of Genetic Polymorphism of ALDH2 in Hematopoietic Stem Cell Transplantation

Aldehyde dehydrogenase 2 (ALDH2) is involved in critically important biological processes, such as the metabolism of aldehydes and aldehyde-induced genotoxicity in hematopoietic stem cells. Given its role in these biological processes, we hypothesized that a functional ALDH2 polymorphism could affect transplantation outcomes after hematopoietic stem cell transplantation. Here, we analyzed the Japanese national registry data for 409 patients who underwent allogeneic bone marrow transplantation (BMT) from HLA-matched unrelated donors. To evaluate the impact of the recipient and donor ALDH2 polymorphism on transplantation outcomes, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for potential confounders. The recipient ALDH2 Lys/Lys genotype was significantly associated with higher transplantation-related mortality (TRM), with an HR relative to Glu/Glu genotype of 2.45 (95% CI,  1.22 to 4.90). The recipient Lys/Lys genotype also tended to be associated with delayed platelet engraftment (HR, .66; 95% CI, .43 to 1.03). In conclusion, we observed increased TRM among recipients with the ALDH2 Lys/Lys genotype in HLA fully matched BMT. We also observed a suggestive association with delayed platelet engraftment, which warrants further examination. These results may suggest that the recipient ALDH2 genotype affects the metabolism of endogenous aldehydes, leading to a significant impact on transplantation outcomes.

Combination of ALDH2 and ADH1B polymorphisms is associated with smoking initiation: A large-scale cross-sectional study in a Japanese population

BACKGROUND

Aldehyde dehydrogenase 2 (ALDH2; rs671, Glu504Lys) and alcohol dehydrogenase 1B (ADH1B; rs1229984, His47Arg) polymorphisms are known to strongly influence alcohol　drinking behavior. Given evidence of an association between smoking and drinking behaviors, we hypothesized that ALDH2/ADH1B polymorphisms might also be associated with smoking initiation, and conducted a cross-sectional study to examine this hypothesis.

METHODS

Study subjects were first-visit outpatients diagnosed not to have cancer at Aichi Cancer Center Hospital between 2001 and 2005, including 4141 never smokers and 2912 ever smokers. Unconditional logistic regression models were applied to estimate odds ratios (OR) and 95% confidence intervals (CI) for smoking initiation by comparing ever smokers with never smokers.

RESULTS

Excessive alcohol drinking was associated with a higher likelihood of ever smoking. After adjustment for drinking behaviors, compared to individuals with ALDH2 Glu/Glu, the ORs of ever smoking were 1.71 (95% CI, 1.49-1.95) and 2.28 (1.81-2.87) among those with ALDH2 Glu/Lys and Lys/Lys, respectively. Combination of ALDH2 Lys/Lys and ADH1B His/His (i.e., the most alcohol-intolerant subpopulation) showed the highest OR [2.44 (1.84-3.23)], whereas combination of ALDH2 Glu/Glu and ADH1B Arg/Arg (i.e., the most alcohol-tolerant subpopulation) showed the lowest OR [0.83 (0.57-1.21)] compared with ALDH2 Glu/Glu and ADH1B His/His.

CONCLUSION

Besides the amount and frequency of alcohol drinking, the combination of ALDH2 and ADH1B polymorphisms predicts smoking initiation. This study suggests that alcohol tolerance regulated by ALDH2 and ADH1B polymorphisms is associated with smoking initiation, and facilitates the development of targeted interventions to reduce smoking prevalence.

Association of genotypes of rs671 withinALDH2 with risk for gastric cardia adenocarcinoma in the Chinese Han population in high- and low-incidence areas

OBJECTIVE

: This study aimed to determine if gastric cardia adenocarcinoma (GCA) risk was associated with the lys (A or *2) allele at the rs671 (glu504lys) polymorphism within the aldehyde dehydrogenase 2 (ALDH2) gene in a Chinese Han population. We also aimed to investigateALDH2 genotypic distributions between subjects from high- and low-incidence areas for both GCA and esophageal squamous cell carcinoma (ESCC).

METHODS

: We designed a case-control study including 2,686 patients with GCA and 3,675 control subjects from high- and low-incidence areas for both GCA and ESCC in China. TaqMan allele discrimination assay was used to genotype the rs671 polymorphism.χ² test and binary logistic regression analysis were used to estimate the odds ratios for the development of GCA, and multivariate ordinal logistic regression was used to analyzeALDH2 genotypic distributions among different groups.

RESULTS

: Compared withALDH2*1/*1 homozygotes,ALDH2*1/*2 andALDH2*2/*2 carriers did not increase the risk for GCA in the Chinese Han population (P>0.05). Interestingly, the ratio of homozygous or heterozygousALDH2 *2 carriers in high-incidence areas for both GCA and ESCC was lower than that in low-incidence areas (P<0.001).

CONCLUSIONS

: Genotypes of rs671 atALDH2 may not increase GCA susceptibility in Chinese Han populations. In addition, theALDH2 genotypic distribution differs between Chinese Han populations from high- and low-incidence areas for both GCA and ESCC. Our findings may shed light on the possible genetic mechanism for the dramatic geographic differences of GCA occurrence in China.

Human Nutrition and Genetic Variation

Human genetic variation is a determinant of nutrient efficacy and of tolerances and intolerances and has the potential to influence nutrient intake values (NIVs). Knowledge derived from the comprehensive identification of human genetic variation offers the potential to predict the physiological and pathological consequences of individual genetic differences and prevent and/or manage adverse outcomes through diet. Nutrients and genomes interact reciprocally; genomes confer differences in nutrient utilization, whereas nutrients effectively modify genome expression, stability, and viability. Understanding the interactions that occur among human genes, including all genetic variants thereof, and environmental exposures is enabling the development of genotype-specific nutritional regimens that prevent disease and promote wellness for individuals and populations throughout the life cycle. Genomic technologies may provide new criteria for establishing NIVs. The impact of a gene variant on NIVs will be dependent on its penetrance and prevalence within a population. Recent experiences indicate that few gene variants are anticipated to be sufficiently penetrant to affect average requirement (AR) values to a greater degree than environmental factors. If highly penetrant gene variants are identified that affect nutrient requirements, the prevalence of the variant in that country or region will determine the feasibility and necessity of deriving more than one AR or upper limit (UL) for affected genetic subgroups.

Mendelian randomisation suggests no beneficial effect of moderate alcohol consumption on the severity of nonalcoholic fatty liver disease

BACKGROUND

Previous epidemiological studies suggest that patients diagnosed with nonalcoholic fatty liver disease (NAFLD) who drink light to moderate amounts of alcohol (up to ~30 g per day) have less severe histological lesions compared with nondrinkers. However, while the cross-sectional nature of current evidence precludes assessment of causality, cumulative lifetime-exposure of moderate alcohol consumption on histological outcomes has never been evaluated.

AIM

To overcome these limitations, a Mendelian randomisation study was performed using a validated genetic variant (rs1229984 A;G) in the alcohol dehydrogenase (ADH1B) gene as a proxy of long-term alcohol exposure.

METHODS

We first assessed whether the instrumental variant (rs1229984) was associated with the amount of alcohol consumption in our cohort. We further explored the association between the variant and histological outcomes; a sample of 466 individuals, including 266 patients with NAFLD confirmed by liver biopsy, was studied.

RESULTS

We found that carriers of the A-allele consumed significantly lower amounts of alcohol compared with noncarriers (2.3 ± 5.3 vs. 8.18 ± 21 g per day, mean ± s.d., P = 0.03). The analysis of association with the disease severity showed that carriers of the A-allele had lower degree of histological steatosis (1.76 ± 0.83 vs. 2.19 ± 0.78, P = 0.03) and lower scores of lobular inflammation (0.54 ± 0.65 vs. 0.95 ± 0.92, P = 0.02) and NAFLD-Activity Score (2.9 ± 1.4 vs. 3.7 ± 1.4, P = 0.015) compared with noncarriers.

CONCLUSION

Mendelian randomisation analysis suggests no beneficial effect of moderate alcohol consumption on NAFLD disease severity.

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.

Alcohol Use and Breast Cancer: A Critical Review

The objective of this study was to outline the biological pathways of alcohol-attributable breast cancer, the epidemiological risk relationship between alcohol consumption and breast cancer, and the global burden of breast cancer incidence and mortality attributable to alcohol consumption, with a focus on light drinking. First, the literature regarding the biological mechanisms of how alcohol affects the risk of breast cancer was reviewed and summarized. Second, a search of meta-analyses that evaluated the risk relationship between alcohol consumption and breast cancer was conducted. Last, the burden of alcohol-attributable breast cancer incidence and mortality was estimated by means of a Population-Attributable Fraction methodology. Data on alcohol consumption were obtained from the Global Information System on Alcohol and Health, and data on cancer incidence and mortality were obtained from the GLOBOCAN database. Alcohol consumption affects breast cancer risk through the alteration in hormone levels and the associated biological pathways, the metabolism of ethanol resulting in carcinogens, and the inhibition of the one carbon metabolism pathway. The systematic review found 15 meta-analyses on the risk relationship between alcohol consumption (also light consumption) and the risk of breast cancer. All but 2 of these analyses showed a dose-response relationship between alcohol consumption and the risk of breast cancer. An estimated 144,000 (95% confidence interval [CI]: 88,000 to 200,000) breast cancer cases and 38,000 (95% CI: 2,400 to 53,000) breast cancer deaths globally in 2012 were attributable to alcohol, with 18.8% of these cases and 17.5% of these deaths affecting women who were light alcohol consumers. All levels of evidence showed a risk relationship between alcohol consumption and the risk of breast cancer, even at low levels of consumption. Due to this strong relationship, and to the amount of alcohol consumed globally, the incidence of and mortality from alcohol-attributable breast cancer is large.

Alcohol consumption and corresponding factors: A novel perspective on the risk factors of esophageal cancer

Esophageal cancer is the eighth most common type of cancer in the world, and the sixth most common cause of mortality from cancer. Alcohol consumption is the major risk factor for esophageal cancer, due to the worldwide prevalence and high carcinogenicity of the ethanol metabolite. In epidemiological studies, the efficiency of alcohol intake to enhance the risk of esophageal cancer is altered by daily ethanol consumption, type of alcoholic beverages ingested, time since quitting drinking, age of drinking initiation, differences in population and subtypes of esophageal cancer. Corresponding factors, including gene polymorphisms, tobacco smoking, oral microorganisms and folate deficiency, reveal a synergistic effect in concurrent alcohol users that may lead to an increased risk of developing esophageal cancer. Consequently, esophageal cancer prevention involves multiple aspects, including quitting drinking and smoking, maintaining an adequate oral health and ingesting adequate quantities of folate, particularly in genetically high-risk populations.

Aldehyde dehydrogenase 2 (ALDH2) and alcohol dehydrogenase 1B (ADH1B) polymorphisms exacerbate bladder cancer risk associated with alcohol drinking: gene-environment interaction

Although a range of chemical exposures (cigarette smoking and occupational exposure) are recognized risk factors for the development of bladder cancer (BCa), many epidemiological studies have demonstrated that alcohol drinking is not associated with BCa risk. Aldehyde dehydrogenase 2 (ALDH2; rs671, Glu504Lys) and alcohol dehydrogenase 1B (ADH1B; rs1229984, His47Arg) polymorphisms impact the accumulation of acetaldehyde, resulting in an increased risk of various cancers. To date, however, no studies evaluating the association between BCa risk and alcohol drinking have considered these polymorphisms. Here, we conducted a matched case-control study to investigate whether ALDH2 and ADH1B polymorphisms influence BCa risk associated with alcohol drinking. Cases were 74 BCa patients and controls were 740 first-visit outpatients without cancer at Aichi Cancer Center Hospital between January 2001 and December 2005. Odds ratio (OR), 95% confidence interval (CI) and gene-environment interaction were assessed by conditional logistic regression analysis with adjustment for potential confounders. Results showed that ALDH2 Glu/Lys was associated with a significantly increased risk of BCa compared with Glu/Glu (OR 2.03, 95% CI 1.14-3.62, P = 0.017). In contrast, ALDH2 Glu/Lys showed no increase in risk among the stratum of never drinkers compared with Glu/Glu, indicating a gene-environment interaction. ADH1B His/Arg had an OR of 1.98 (1.20-3.24, P = 0.007) compared with His/His. ADH1B Arg+ showed a similar OR and 95% CI. Individuals with ALDH2 Glu/Lys and ADH1B Arg+ had the highest risk of BCa compared with ALDH2 Glu/Glu and ADH1B His/His [OR 4.00 (1.81-8.87), P = 0.001].

Prognostic Value of Drinking Status and Aldehyde Dehydrogenase 2 Polymorphism in Patients With Head and Neck Squamous Cell Carcinoma

Background

The association between alcohol drinking, aldehyde dehydrogenase 2 (ALDH2) polymorphism, and survival in patients with head and neck squamous cell carcinoma (HNSCC) remains unclear.

Methods

We performed a retrospective cohort study of 267 HNSCC patients at Aichi Cancer Center. Of these, 65 patients (24%) were non-drinkers, 104 (39%) were light drinkers (ethanol <46 g or <5 days/week), 46 (17%) were moderate drinkers (ethanol intake 46–68 g/day and ≥5 days/week), and 52 (20%) were heavy drinkers (ethanol intake ≥69 g and ≥5 days/week). The prognostic value of pre-treatment drinking status and ALDH2 polymorphism was investigated using multivariate proportional hazard models.

Results

Drinking status was associated with disease-free survival (DFS) in HNSCC patients, with marginal statistical significance (5-year DFS: 67.9% [95% confidence interval {CI}, 53.8–78.4%] for non-drinkers, 57.6% [95% CI, 47.4–66.6%] for light drinkers, 46.1% [95% CI, 30.8–60.1%] for moderate drinkers, and 43.5% [95% CI, 29.3–56.9%] for heavy drinkers; P = 0.088). However, this association lost significance when multivariate analyses were adjusted for established prognostic factors. ALDH2 genotype was not significantly associated with DFS in HNSCC patients (5-year DFS: 85.7% [95% CI, 53.9–96.2%] for Lys/Lys, 56.2% [95% CI, 47.4–64.1%] for Glu/Lys, and 50.5% [95% CI, 40.3–59.7%] for Glu/Glu; P = 0.154). After stratification by ALDH2 genotype, we observed a significant positive dose-response relationship between drinking status and DFS in HNSCC patients with ALDH2 Glu/Glu (P_trend = 0.029).

Conclusions

In this study, we identified a significant positive dose-response relationship between pre-treatment drinking status and DFS in HNSCC patients with ALDH2 Glu/Glu. To confirm this association, further study is warranted.

Microbial influences on hormesis, oncogenesis, and therapy: A review of the literature

Utilization of environmental stimuli for growth is the main factor contributing to the evolution of prokaryotes and eukaryotes, independently and mutualistically. Epigenetics describes an organism's ability to vary expression of certain genes based on their environmental stimuli. The diverse degree of dose-dependent responses based on their variances in expressed genetic profiles makes it difficult to ascertain whether hormesis or oncogenesis has or is occurring. In the medical field this is shown where survival curves used in determining radiotherapeutic doses have substantial uncertainties, some as large as 50% (Barendsen, 1990). Many in-vitro radiobiological studies have been limited by not taking into consideration the innate presence of microbes in biological systems, which have either grown symbiotically or pathogenically. Present in-vitro studies neglect to take into consideration the varied responses that commensal and opportunistic pathogens will have when exposed to the same stimuli and how such responses could act as stimuli for their macro/microenvironment. As a result many theories such as radiation carcinogenesis explain microscopic events but fail to describe macroscopic events (Cohen, 1995). As such, this review shows how microorganisms have the ability to perturb risks of cancer and enhance hormesis after irradiation. It will also look at bacterial significance in the microenvironment of the tumor before and during treatment. In addition, bacterial systemic communication after irradiation and the host's immune responses to infection could explain many of the phenomena associated with bystander effects. Therefore, the present literature review considers the paradigms of hormesis and oncogenesis in order to find a rationale that ties them all together. This relationship was thus characterized to be the microbiome.

Glu504Lys Single Nucleotide Polymorphism of Aldehyde Dehydrogenase 2 Gene and the Risk of Human Diseases

Aldehyde dehydrogenase (ALDH) 2 is a mitochondrial enzyme that is known for its important role in oxidation and detoxification of ethanol metabolite acetaldehyde. ALDH2 also metabolizes other reactive aldehydes such as 4-hydroxy-2-nonenal and acrolein. The Glu504Lys single nucleotide polymorphism (SNP) of ALDH2 gene, which is found in approximately 40% of the East Asian populations, causes defect in the enzyme activity of ALDH2, leading to alterations in acetaldehyde metabolism and alcohol-induced "flushing" syndrome. Evidence suggests that ALDH2 Glu504Lys SNP is a potential candidate genetic risk factor for a variety of chronic diseases such as cardiovascular disease, cancer, and late-onset Alzheimer's disease. In addition, the association between ALDH2 Glu504Lys SNP and the development of these chronic diseases appears to be affected by the interaction between the SNP and lifestyle factors such as alcohol consumption as well as by the presence of other genetic variations.

Genetic susceptibility factors for alcohol-induced chronic pancreatitis

Chronic pancreatitis is a progressive inflammatory disease of the pancreas and frequently associated with immoderate alcohol consumption. Since only a small proportion of alcoholics eventually develop chronic pancreatitis genetic susceptibility factors have long been suspected to contribute to the pathogenesis of the disease. Smaller studies in ethnically defined populations have found that not only polymorphism in proteins involved in the metabolism of ethanol, such as Alcohol Dehydrogenase and Aldehyde Dehydrogenase, can confer a risk for developing chronic pancreatitis but also mutations that had previously been reported in association with idiopathic pancreatitis, such as SPINK1 mutations. In a much broader approach employing genome wide search strategies the NAPS study found that polymorphisms in the Trypsin locus (PRSS1 rs10273639), and the Claudin 2 locus (CLDN2-RIPPLY1-MORC4 locus rs7057398 and rs12688220) confer an increased risk of developing alcohol-induced pancreatitis. These results from North America have now been confirmed by a European consortium. In another genome wide approach polymorphisms in the genes encoding Fucosyltransferase 2 (FUT2) non-secretor status and blood group B were not only found in association with higher serum lipase levels in healthy volunteers but also to more than double the risk for developing alcohol-associated chronic pancreatitis. These novel genetic associations will allow to investigate the pathophysiological and biochemical basis of alcohol-induced chronic pancreatitis on a cellular level and in much more detail than previously possible.

Aldehyde Dehydrogenase Polymorphisms and Blood Pressure Elevation in the Japanese: A Cross-Sectional and a Longitudinal Study over 20 Years in the Shimane CoHRE Study

PURPOSE

Effects of a genetic polymorphism in the aldehyde dehydrogenase-2 (ALDH2) on blood pressure (BP) were investigated in a cross-sectional and a longitudinal study over 20 years on Japanese rural residents.

METHODS

Health examinations were held through 2006 to 2012, and 3,202 participates were recruited for this study. Among these participants, 560 individuals had medical records that were obtained in a health examination 20 years ago. Genomic DNA of participants was extracted from blood and the genotype of a polymorphism in ALDH2 was determined by the TaqMan method. Multivariate regression analyses were performed to examine association between BP and the genetic polymorphism in the ALDH2 gene.

RESULTS

Systolic and diastolic BP were higher in the ALDH2 (∗)1/(∗)1 than the others (ALDH2 (∗)1/(∗)2 or ALDH2 (∗)2/(∗)2). Genetic variation of the ALDH2 gene apparently influenced drinking behavior as the number of the drinkers was significantly reduced in the ALDH2 (∗)2/(∗) 2 after 20 years of the observation period. This polymorphism, however, did not confer a risk for BP increase in the longitudinal observation.

CONCLUSION

The present cross-sectional study confirmed a genetic effect of the ALDH2 gene on BP. In contrast, no significant effects on BP were identified in a longitudinal study, which may require a careful consideration.

Metabolic methanol: molecular pathways and physiological roles

Methanol has been historically considered an exogenous product that leads only to pathological changes in the human body when consumed. However, in normal, healthy individuals, methanol and its short-lived oxidized product, formaldehyde, are naturally occurring compounds whose functions and origins have received limited attention. There are several sources of human physiological methanol. Fruits, vegetables, and alcoholic beverages are likely the main sources of exogenous methanol in the healthy human body. Metabolic methanol may occur as a result of fermentation by gut bacteria and metabolic processes involving S-adenosyl methionine. Regardless of its source, low levels of methanol in the body are maintained by physiological and metabolic clearance mechanisms. Although human blood contains small amounts of methanol and formaldehyde, the content of these molecules increases sharply after receiving even methanol-free ethanol, indicating an endogenous source of the metabolic methanol present at low levels in the blood regulated by a cluster of genes. Recent studies of the pathogenesis of neurological disorders indicate metabolic formaldehyde as a putative causative agent. The detection of increased formaldehyde content in the blood of both neurological patients and the elderly indicates the important role of genetic and biochemical mechanisms of maintaining low levels of methanol and formaldehyde.

Genotyping on ALDH2: comparison of four different technologies

Objectives

This study aimed to compare the accuracy and performance of four genotyping methods for detecting single nucleotide polymorphisms (SNPs) in aldehyde dehydrogenase-2 (ALDH2), which is the principal enzyme involved in alcohol metabolism.

Design and Methods

We genotyped rs671 of ALDH2 in 96 coronary heart disease (CHD) patients with four methods including high resolution melting analysis (HRM), TaqMan allelic discrimination assay (TaqMan), allele-specific PCR (AS-PCR) and pyrosequencing. Meanwhile, we compared the accuracy and performance of these methods.

Results

All selected patients were successfully genotyped with referred methods. The results of these four assays showed 100% concordant results and had 100% accuracy as verified by Sanger sequencing.

Conclusions

All of the referred methods can be used for genotyping ALDH2 rs671 with the same accuracy compared to Sanger sequencing. In small size of clinical samples, HRM and AS-PCR outperform over others due to their lower cost and less hands-on operation, which are suitable for clinical application.

Alcohol consumption mediates the relationship between ADH1B and DSM-IV alcohol use disorder and criteria

OBJECTIVE

A single nucleotide variation in the alcohol dehydrogenase 1B (ADH1B) gene, rs1229984, produces an ADH1B enzyme with faster acetaldehyde production. This protective variant is associated with lower alcohol consumption and lower risk for alcohol use disorders (AUDs). Based on the premise that faster ADH1B kinetics decreases alcohol consumption, we formally tested if the association between ADH1B variant rs1229984 and AUDs occurs through consumption. We also tested whether the association between rs1229984 and each of the 11 Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), AUD criteria occurs through consumption.

METHOD

A total of 1,130 lifetime drinkers from an Israeli household sample were assessed with a structured interview and genotyped for rs1229984 (protective allele frequency = 0.28). Logistic regression evaluated the association between rs1229984 and each phenotype (AUDs, 11 individual DSM-IV criteria). For phenotypes significantly related to rs1229984, the effect through consumption was tested with logistic regression and bootstrapping.

RESULTS

ADH1B rs1229984 was significantly associated with AUDs and six criteria, with odds ratios ranging from 1.32 to 1.96. The effect through consumption was significant for these relationships, explaining 23%-74% of the total ADH1B effect.

CONCLUSIONS

This is the first study to show that ADH1B rs1229984 is related to 6 of the 11 DSM-IV AUD criteria and that alcohol consumption explained a significant proportion of these associations and the association of ADH1B with AUDs. Better understanding of the relationship between ADH1B and the DSM-IV AUD criteria, including effects through consumption, will enhance our understanding of the etiologic model through which AUDs can occur.

Genetic alcohol sensitivity regulated by ALDH2 and ADH1B polymorphisms is strongly associated with depression and anxiety in Japanese employees

BACKGROUND

Although alcohol-related disorders (ARD) have been shown to be accompanied by comorbid depressive and anxiety disorders, and alcohol metabolic enzyme genes, ADH1B and ALDH2 polymorphisms, have been associated with an increased risk of ARD, no studies have been conducted to evaluate the associations between these genetic polymorphisms and anxiety or depression.

METHOD

A total of 1944 Japanese workers were interviewed regarding their depressive and anxiety disorders, including suicidality, by a brief psychiatric structured interview (MINI). We investigated the relationship of ADH1B rs1229984 and ALDH2 rs671 polymorphism combinations with mental disorder risks. Logistic regression analysis was used to evaluate the associations between those polymorphisms and anxiety/depressive disorders, adjusting for sex, age, and job rank. The degree of alcohol sensitivity was classified into five groups according to the combination of two enzyme genotypes (Group I-V, in order from the lowest alcohol sensitivity).

RESULTS

Those with ALDH2(*)1/(*)1 and ADH1B(*)1/(*)1 were likely to be at an increased risk of depressive and anxiety disorders as well as ARD. This tendency was more apparent among non-drinkers (OR 9.20, 95% CI 1.66-50.89). No adverse effects of ALDH2 or ADH1B alone were observed with mental disorder risks. Likewise, analyses conducted combining job rank and genetic alcohol sensitivity showed no material associations with such risks.

CONCLUSIONS

Genetic alcohol sensitivity, especially that with the genotype combination of ALDH2(*)1/(*)1 and ADH1B(*)1/(*)1, was significantly associated with an increased risk of depressive and anxiety disorders as well as ARD.

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 polymorphisms of ADH1B, ADH1C and ALDH2, alcohol consumption, and the risk of gastric cancer: the Japan Public Health Center-based prospective study

The association between alcohol consumption, genetic polymorphisms of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) and gastric cancer risk is not completely understood. We investigated the association between ADH1B (rs1229984), ADH1C (rs698) and ALDH2 (rs671) polymorphisms, alcohol consumption and the risk of gastric cancer among Japanese subjects in a population-based, nested, case-control study (1990-2004). Among 36 745 subjects who answered the baseline questionnaire and provided blood samples, 457 new gastric cancer cases matched to 457 controls were used in the analysis. The odds ratios (OR) and corresponding 95% confidence intervals (CI) were calculated using logistic regression models. No association was observed between alcohol consumption, ADH1B (rs1229984), ADH1C (rs698) and ALDH2 (rs671) polymorphisms and gastric cancer risk. However, considering gene-environmental interaction, ADH1C G allele carriers who drink ≥150 g/week of ethanol had a 2.5-fold increased risk of gastric cancer (OR = 2.54, 95% CI = 1.05-6.17) relative to AA genotype carriers who drink 0 to <150 g/week (P for interaction = 0.02). ALDH2 A allele carriers who drink ≥150 g/week also had an increased risk (OR = 2.08, 95% CI = 1.05-4.12) relative to GG genotype carriers who drink 0 to < 150 g/week (P for interaction = 0.08). To find the relation between alcohol consumption and gastric cancer risk, it is important to consider both alcohol consumption level and ADH1C and ALDH2 polymorphisms.

Transcriptome changes in Eriocheir sinensis megalopae after desalination provide insights into osmoregulation and stress adaption in larvae

Eriocheir sinensis, an extremely invasive alien crab species, has important economic value in China. It encounters different salinities during its life cycle, and at the megalopal stage it faces a turning point regarding the salinity in its environment. We applied RNA sequencing to E. sinensis megalopae before (MB) and after (MA) desalination, resulting in the discovery of 21,042 unigenes and 908 differentially expressed genes (DEGs, 4.32% of the unigenes). The DEGs primarily belonged to the Gene Ontology groups “Energy metabolism,” “Oxidoreductase activity,” “Translation,” “Transport,” “Metabolism,” and “Stress response.” In total, 33 DEGs related to transport processes were found, including 12 proton pump genes, three ATP-binding cassettes (ABCs), 13 solute carrier (SLC) family members, two sweet sugar transporter (ST) family members and three other substance transporters. Mitochondrial genes as well as genes involved in the tricarboxylic acid cycle, glycolytic pathway, or β-oxidation pathway, which can generate energy in the form of ATP, were typically up-regulated in MA. 11 unigenes related to amino acid metabolism and a large number of genes related to protein synthesis were differentially expressed in MB and MA, indicating that E. sinensis possibly adjusts its concentration of free amino acid osmolytes for hyper-osmoregulation. Additionally, 33 salinity and oxidative stress induced genes were found to be differentially expressed, such as the LEA2, HSPs, GST and coagulation factor genes. Notably, LEA2 is an extremely hydrophilic protein that responds to desiccation and reported for the first time in crabs. Therefore, we suppose that when the environment is hypo-osmotic, the megalopae might compensate for ion loss via hyper-osmoregulation by consuming more energy, accompanied by a series of stress induced adaptions. This study provides the first genome-wide transcriptome analysis of E. sinensis megalopae for studying its osmoregulation and stress adaption mechanisms.

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.

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.

Alcohol dehydrogenase-1B Arg47His polymorphism is associated with head and neck cancer risk in Asian: a meta-analysis

Head and neck cancers (HNCs) include cancers which arise in oral cavity, pharynx, and larynx. Recent studies have demonstrated that alcohol drinking is an established risk factor for HNC. The alcohol dehydrogenase-1B (ADH1B) plays a major role in the oxidized process of alcohol. To investigate the association of ADH1B Arg47His with HNC in Asian populations, we combined all available studies into a meta-analysis. A total of 2186 cases and 4488 controls were analyzed for this meta-analysis. We used odds ratios (ORs) to assess the strength of the association and 95% confidence intervals (CIs) to give a sense of the precision of the estimate. The ADH1B*47Arg allele was found to be associated with increased risk of HNC in Asians, with the pooled odds ratios (ORs) (Arg/Arg vs. Arg/His + His/His: OR = 2.35, 95% CI = 1.56-3.55, P < 0.0001) in all eight studies. In the subgroup analysis by alcohol consumption, the Arg/Arg vs. Arg/His + His/His genotype was found to be interacted with alcohol consumption, with the OR = 2.44, 95% CI = 1.85-3.20 among ever drinkers. Besides, no significant association was found in non-drinkers. This meta-analysis revealed that ADH1B Arg47His (rs1229984) polymorphism could increase the risk of HNC in Asians significantly.

Factors associated with the presence of multiple Lugol-voiding lesions in patients with esophageal squamous-cell carcinoma

Multicentric squamous dysplasia of the esophagus is characterized by multiple Lugol-voiding lesions (LVLs) on Lugol chromoendoscopy. Multiple LVLs are associated with a very high risk of multiple cancers arising in the esophagus as well as the head and neck. To gain insight into the pathogenesis of multiple LVLs of the esophageal mucosa, we studied risk factors for the development of such lesions in 76 patients who had a current or previous diagnosis of esophageal squamous cell carcinoma. All patients underwent Lugol chromoendoscopy of the esophageal mucosa. The history of tobacco and alcohol use was documented. Polymorphisms of the aldehyde dehydrogenase type 2 (ALDH2) gene were identified by polymerase chain reaction using sequence-specific primers. Clinical factors related to multiple LVLs were analyzed. All patients with multiple LVLs were drinkers. On univariate analysis, male sex (odds ratio [OR] 15, 95% confidence interval [CI] 1.84-122.45: P = 0.011), presence of the ALDH2-2 allele (OR 4.5, 95% CI 1.55-13.24: P = 0.006), and smoking index ≥1000 (OR 2.6, 95% CI 1.02-6.6: P = 0.045) were associated with multiple LVLs. On multivariate analysis, male sex (OR 10.02, 95% CI 1.13-88.44: P = 0.038) and presence of the ALDH2-2 allele (OR 4.56, 95% CI 1.4-14.82: P = 0.012) were associated with multiple LVLs. Among drinkers, a daily alcohol intake of ≥100 g pure ethanol with the ALDH2-2 allele (OR 17.5, 95% CI 1.97-155.59: P = 0.01) and a daily alcohol intake of <100 g pure ethanol with the ALDH2-2 allele (OR 8.85, 95% CI 1.68-46.69: P = 0.01) more strongly correlated with multiple LVLs than did a daily alcohol intake of <100 g pure ethanol without the ALDH2-2 allele, whereas a daily alcohol intake of ≥100 g pure ethanol without the ALDH2-2 allele (OR 4.0, 95% CI 0.54-29.81: P = 0.18) did not. In conclusion, male sex and the ALDH2-2 allele are associated with an increased risk for multiple LVLs of the esophageal mucosa in patients with esophageal squamous cell carcinoma. Among drinkers with the ALDH2-2 allele, the risk of multiple LVLs increased in parallel to the daily alcohol intake.

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.

Enhancement of Alcohol Metabolism by Sprouted Peanut Extract in SD Rats

Excessive ethanol intake is known to induce a number of physiological symptoms, including headache, dizziness and vertigo. In this study, we investigated the attenuation effect of sprouted peanut extract (SPE) on ethanol-induced hangover in male Sprague-Dawley rats. The animals were divided into five groups: the control group, which was administered ethanol only; the ethanol plus SPE experimental groups, which were administered ethanol and 100, 200, or 400 mg SPE/kg b.w.; and the positive control group, which was administered ethanol plus DAWN808^®, a commercial product. SPE-suspended water was delivered to rats via gavage 15 h and 30 min before the administration of ethanol. Blood was collected from the tail 0, 1, 3, and 5 h after ethanol administration. The results showed that serum ethanol concentrations were significantly lower in SPE treated groups than in the control group. Furthermore, hepatic alcohol and acetaldehyde dehydrogenase activities were enhanced by SPE in a dose dependent manner. These results suggest that SPE could be useful in attenuating hangover after alcohol consumption.

The interplay between alcohol consumption, oral hygiene, ALDH2 and ADH1B in the risk of head and neck cancer

Alcohol consumption is an established risk factor for head and neck cancer (HNC). The major carcinogen from alcohol is acetaldehyde, which may be produced by humans or by oral microorganisms through the metabolism of ethanol. To account for the different sources of acetaldehyde production, the current study examined the interplay between alcohol consumption, oral hygiene (as a proxy measure for the growth of oral microorganisms), and alcohol-metabolizing genes (ADH1B and ALDH2) in the risk of HNC. We found that both the fast (*2/*2) and the slow (*1/*1+ *1/*2) ADH1B genotypes increased the risk of HNC due to alcohol consumption, and this association differed according to the slow/non-functional ALDH2 genotypes (*1/*2+ *2/*2) or poor oral hygiene. In persons with the fast ADH1B genotype, the HNC risk associated with alcohol drinking was increased for those with the slow/non-functional ALDH2 genotypes. For those with the slow ADH1B genotypes, oral hygiene appeared to play an important role; the highest magnitude of an increased HNC risk in alcohol drinkers occurred among those with the worst oral hygiene. This is the first study to show that the association between alcohol drinking and HNC risk may be modified by the interplay between genetic polymorphisms of ADH1B and ALDH2 and oral hygiene. Although it is important to promote abstinence from or reduction of alcohol drinking to decrease the occurrence of HNC, improving oral hygiene practices may provide additional benefit.

Functional polymorphism in aldehyde dehydrogenase-2 gene associated with risk of tuberculosis

Background

The well-known genetic polymorphisms in ADH1B(His47Arg) and ALDH2(Glu487Lys) have dramatic effects on the rate of metabolizing alcohol and acetaldehyde. We investigated possible involvement of these functional polymorphisms in other common complex-trait diseases.

Methods

The genetic effects of these two polymorphisms on hepatitis, asthma, type-2 diabetes mellitus (T2DM), and tuberculosis (TB) were examined in a Korean population.

Results

We demonstrated that the well-known functional polymorphism of a primary alcohol-metabolizing enzyme (ALDH2 Glu487Lys) has a strong genetic association with the risk of TB. The frequency of the minor allele (ALDH2*487Lys) was found to be much lower in TB patients (freq. = 0.099/n = 477) than among controls (freq. = 0.162/n = 796) (P = 0.00001, OR (95% confidential interval) = 0.57 (0.45-0.74)). Our data may indicate that TB was once an endemic disease, which exerted selection pressure for higher frequencies of ALDH2*487Lys in Asian populations. In addition, the calculated attributable fraction (AF) indicates that 39.5% of TB patients can attribute their disease to the detrimental effects of ALDH2Glu487Glu.

Conclusion

Our results suggest that this polymorphism is one of the genetic components of TB, at least in the Korean population.

Micronucleus induction by oxidative metabolites of trichloroethylene in cultured human peripheral blood lymphocytes: a comparative genotoxicity study

The genotoxic effects of oxidative metabolites of trichloroethylene (TCE), namely chloral hydrate, trichloroacetic acid (TCA), dichloroacetic acid (DCA), and trichloroethanol (TCEOH) were examined in human peripheral blood lymphocytes. In this context, lymphocytes were exposed in vitro to 25, 50, and 100 μg/ml concentrations of these metabolites separately for a period of 48 h and examined for micronucleus (MN) induction through flow cytometer. At 50 μg/ml TCE metabolites, TCA (6.33 ± 0.56 %), DCA (5.06 ± 0.55), and TCEOH (4.70 ± 1.73) induced highly significant (p<0.001) frequency of MN in comparison to control (1.03 ± 0.40) suggestive of their genotoxic potential. However, exposure of 100 μg/ml of all the metabolites consistently declined the frequencies of MN which in some cases was equable to that of observed at 25 μg/ml. Further, cytotoxicity and cell cycle disturbances were also measured to find out the association of these endpoints with the MN induction. DNA content analysis revealed 3-4-fold elevation of S-phase at all the concentrations tested. Particularly, at 100 μg/ml, treatment elevation of S-phase was significantly (p<0.0001) higher as compared to the control. Present findings together with earlier reports indicate that TCE induces genotoxicity through its metabolites. Interaction of these metabolites with DNA, as evident by elevated S-phase, seems to be the major cause of MN induction. However, involvement of spindle disruption cannot be ruled out. This comparative study also suggests that after TCE exposure, the metabolic efficiency of human to generate oxidative metabolites determines the extent of genotoxicity.

Association study of DKK2 polymorphisms with alcohol dependence and alcohol-related harm

BACKGROUND

Alcohol dependence (AD) is a common disorder with both environmental and genetic factors. Previous studies have shown that the genomic region from chromosome 4q22-q32 is closely associated with AD. Furthermore, a study with Irish subjects revealed that the polymorphisms of Dickkopf WNT signaling pathway inhibitor (DKK2), located at 4q25, showed a significant association with AD.

METHODS

We conducted a replication study of the association between DKK2 polymorphisms and AD with 459 alcoholics and 444 normal controls, all of Korean descendent. To rank the AD of the subjects, Alcohol Use Disorders Identification Test (AUDIT) was utilized. Using the TaqMan assay, 21 single-nucleotide polymorphisms (SNPs) of DKK2 were genotyped.

RESULTS

Our analysis showed that rs17037102 (Q146R) was significantly associated with overall AUDIT score (p = 0.003, p(corr)  = 0.05 in dominant model). Further analysis showed that the SNP was significantly associated with alcohol-related harm (p = 0.001, p(corr)  = 0.02 in co-dominant model). Several other SNPs, including the 3 SNPs which were associated with AD in European population, showed marginal associations that were erased when corrections for multiple testing was applied. Furthermore, rs17037102 was in linkage disequilibrium with the nonexonic DKK2 SNPs which showed associations with AD in the previous study with Irish population, which suggests that rs17037102 may be the causal SNP.

CONCLUSIONS

We found 1 DKK2 SNP to be significantly associated with alcohol-related harm in alcoholic subjects. The SNP might be the causal SNP which led its linked SNPs to show associations in previous studies.

Immune response to acetaldehyde-human serum albumin adduct among healthy subjects related to alcohol intake

Acetaldehyde (AA) is the main metabolic product in ethanol metabolism, although it can also derive from sources of airborne pollution. As a typical aldehyde, AA is able to react with a variety of molecular targets, including DNA and protein. This property justifies the hypothesis of a immune reaction against this kind of adduct, to be studied by a seroprevalence screening approach. In this study, the correlation between drinking habits and the amount of circulating AA-human serum albumin adduct (AA-HSA) was evaluated in a group of healthy subjects, non alcohol-addicted. Daily ethanol intake (grams) was inferred for each subject using the information collected through a questionnaire, and AA-HSA antibodies (AA-HSA ab) analyses were performed using the Displacement Assay on whole blood samples. The findings showed a correlation between ethanol intake and immune response to molecular adduct. These results underscore the evaluation of AA-HSA ab amount as a suitable molecular marker for alcohol intake that can be applied in future investigations on a large scale for prevention screening.