Impact of theAlcohol-Dehydrogenase(ADH)1CandADH1Bpolymorphisms on drinking behavior in nonalcoholic Japanese

Fanconi anemia and Aldehyde Degradation Deficiency Syndrome: Metabolism and DNA repair protect the genome and hematopoiesis from endogenous DNA damage

We have identified a set of Japanese children with hypoplastic anemia caused by combined defects in aldehyde degrading enzymes ADH5 and ALDH2. Their clinical characteristics overlap with a hereditary DNA repair disorder, Fanconi anemia. Our discovery of this disorder, termed Aldehyde Degradation Deficiency Syndrome (ADDS), reinforces the notion that endogenously generated aldehydes exert genotoxic effects; thus, the coupled actions of metabolism and DNA repair are required to maintain proper hematopoiesis and health.

Impact of Alcohol Dehydrogenase 7 Polymorphism and Alcohol Consumption on Risk of Head and Neck Squamous Cell Carcinoma: A Korean Case-Control Study

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is closely associated with alcohol consumption and individual genetic susceptibility, such as single nucleotide polymorphism (SNP) of alcohol dehydrogenase (ADH). This study aimed to investigate the association of ADH7 SNPs with the risk of HNSCC.

METHODS

We analyzed ADH7 rs1573496C>G, rs3737482T>C, rs1154460G>A, and rs284787T>C SNPs in 250 patients with HNSCC and 322 controls in the Korean populations. Genotyping was conducted using the TaqMan assay. Linkage disequilibrium and haplotypes were analyzed.

RESULTS

The odds ratios (OR) and 95% confidence intervals (CI) of the CT and CC genotypes of ADH7 rs3737482T>C were 0.48 (0.29-0.78) and 0.69 (0.49-0.96), indicating a significantly decreased risk. In SNP of rs1154460G>A, the OR and 95% CI of the AA genotype was 1.63 (1.11-2.40), showing a significant increase in the risk. Furthermore, SNPs of ADH7 rs3737482T>C and ADH7 rs1154460G>A exhibit synergistic interactions with alcohol composition on the risk of HNSCC. None of the haplotypes were associated with the risk of HNSCC.

CONCLUSIONS

ADH7 rs3737482T>C and rs1154460G>A SNPs are associated with the risk of development of HNSCC in Koreans. They could serve as molecular biological markers to screen high-risk groups for HNSCC.

Associations between ALDH Genetic Variants, Alcohol Consumption, and the Risk of Nasopharyngeal Carcinoma in an East Asian Population

Nasopharyngeal carcinoma (NPC) and alcohol flush syndrome are thought to be strongly influenced by genetic factors and are highly prevalent amongst East Asians. Diminished activity of aldehyde dehydrogenase (ALDH), a major enzyme in the alcohol-metabolizing pathway, causes the flushing syndrome associated with alcoholic consumption. The genetic effect of ALDH isoforms on NPC is unknown. We therefore investigated the association between the genetic polymorphisms of all 19 ALDH isoforms and NPC among 458 patients with NPC and 1672 age- and gender-matched healthy controls in Taiwan. Single-nucleotide polymorphisms (SNPs) located between the 40,000 base pairs upstream and downstream of the 19 ALDH isoform coding regions were collected from two genome-wise association studies conducted in Taiwan and from the Taiwan Biobank. Thirteen SNPs located on ALDH4A1, ALDH18A1, ALDH3B2, ALDH1L2, ALDH1A2, and ALDH2 Glu487Lys (rs671) were associated with NPC susceptibility. Stratification by alcohol status revealed a cumulative risk effect for NPC amongst drinkers and non-drinkers, with odds ratios of 4.89 (95% confidence interval 2.15–11.08) and 3.57 (1.97–6.47), respectively. A synergistic effect was observed between SNPs and alcohol. This study is the first to report associations between genetic variants in 19 ALDH isoforms, their interaction with alcohol consumption and NPC in an East Asian population.

Alcohol Dehydrogenases, Aldehyde Dehydrogenases, and Alcohol Use Disorders: A Critical Review

Alcohol use disorders (AUDs) are complex traits, meaning that variations in many genes contribute to the risk, as does the environment. Although the total genetic contribution to risk is substantial, most individual variations make only very small contributions. By far the strongest contributors are functional variations in 2 genes involved in alcohol (ethanol [EtOH]) metabolism. A functional variant in alcohol dehydrogenase 1B (ADH1B) is protective in people of European and Asian descent, and a different functional variant in the same gene is protective in those of African descent. A strongly protective variant in aldehyde dehydrogenase 2 (ALDH2) is essentially only found in Asians. This highlights the need to study a wide range of populations. The likely mechanism of protection against heavy drinking and AUDs in both cases is alteration in the rate of metabolism of EtOH that at least transiently elevates acetaldehyde. Other ADH and ALDH variants, including functional variations in ADH1C, have also been implicated in affecting drinking behavior and risk for alcoholism. The pattern of linkage disequilibrium in the ADH region and the differences among populations complicate analyses, particularly of regulatory variants. This critical review focuses upon the ADH and ALDH genes as they affect AUDs.

ADH1B, ALDH2, GSTM1 and GSTT1 Gene Polymorphic Frequencies among Alcoholics and Controls in the Arcadian Population of Central India

Background: Epidemiological research has highlighted the global burden of primary liver cancer cases due to alcohol consumption, even in a low consumption country like India. Alcohol detoxification is governed by ADH1B, ALDH2, GSTM1 and GSTT1 genes that encode functional enzymes which are coordinated with each other to remove highly toxic metabolites i.e. acetaldehyde as well as reactive oxygen species generated through detoxification processes. Some communities in the population appears to be at greater risk for development of the liver cancer due to genetic predispositions. Methods: The aim of this study was to screen the arcadian population of central India in order to investigate and compare the genotype distribution and allele frequencies of alcohol metabolizing genes (ADH1B, ALDH2, GSTM1 and GSTT1) in both alcoholic (N=121) and control (N=145) healthy subjects. The gene polymorphism analysis was conducted using PCR and RFLP methods. Results: The allele frequency of ALDH2 *1 was 0.79 and of ALDH2*2 was 0.21 (OR:1.12; CI (95%): 0.74-1.71). The null allele frequency for GSTM1 was 0.28 (OR:0.85; CI (95%): 0.50-1.46) and for GSTT1 was 0.20 (OR:1.93; CI (95%): 1.05-3.55). No gene polymorphism for ADH1B was not observed. The total prevalence of polymorphisms was 3.38% for ALDH2, GSTM1 and GSTT1. Conclusion: The results of this study suggested that individuals of the Central India population under study are at risk for liver disorders due to ALDH2, GSTM1 and GSTT1 gene polymorphisms. This results may have significance for prevention of alcohol dependence, alcoholic liver disorders and the likelihood of liver cancer.

An improved PCR-CTPP assay for the detection of ADH1B Arg48His polymorphism

BACKGROUND

ADH1B Arg48His polymorphism is associated with the development of alcohol-related diseases. In this study, we aimed to explore an improved polymerase chain reaction with confronting two-pair primers (PCR-CTPP) assay for the detection of ADH1B Arg48His polymorphism.

METHODS

A mismatch was introduced at the 3' end of each of the two allele-specific to increase the specificity of the reaction. But beyond that, a new mismatch at-3 positions of outer primers was designed to decrease the efficiency of the aforementioned primers and depresses the amplification of an internal nonspecific DNA control. A total of 180 samples from healthy volunteers Han Chinese were tested to evaluate this new assay.

RESULTS

The protocol of PCR-CTPP was successful for genotyping of ADH1B Arg48His. The results from the improved PCR-CTPP assay were confirmed by Sanger sequencing, and correct genotyping rates were 100%.The genotype frequencies were 49.44% (89 cases) for His/His, 46.67% (84 cases) for Arg/His, and 3.89% (seven cases) for Arg/Arg respectively.

CONCLUSIONS

This improved PCR-CTPP assay is simple, rapid, cost-effective, and reliable, specific for the detection of ADH1B Arg48His polymorphism in most clinical diagnostic laboratories.

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.

The allele frequency of ALDH2*Glu504Lys and ADH1B*Arg47His for the Ryukyu islanders and their history of expansion among East Asians

OBJECTIVES

A cline of frequencies of the derived allele of the ALDH2 gene, which causes a deficiency of an enzyme and "facial flushing" in humans who drink alcohol, has been known among the people of the Japanese archipelago. This cline is conventionally explained by admixture with immigrants from the Asian continent occurring during the Yayoi period. Previous studies lack sufficient data from the peripheral regions of the indigenous Jomon people, and those data the ADH1B gene that is involved in the Class I ADH gene cluster and contains another variant leading to a functional change.

METHODS

We focused on the southwestern-most people from the Ryukyu Islands (n = 218) and those from northern Kyushu (n = 21) where the Yayoi immigrants likely arrived. We investigated both the Class I ADH and ALDH2 loci, as well as neutral genetic markers.

RESULTS

In the Ryukyu Islands, the frequencies of the ancestral alleles in both loci were always higher than those in mainland Japan, while the frequencies of ADH1B were less than those of the derived allele. A haplotype block was not observed in ALDH2 but was in Class I ADH.

DISCUSSION

Our data suggest that the derived allele of ALDH2 came with the Yayoi immigrants from the Asian continent to the Japanese archipelago. However, the derived allele of ADH1B is unlikely to be related to the Yayoi migration. Therefore, we postulate that the expansion of the derived allele of ADHIB in East Asia could be traced back to the last glacial period.

Relationships of alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) genotypes with alcohol sensitivity, drinking behavior and problem drinking in Japanese older men

OBJECTIVES

Many East Asians have the genetic polymorphisms rs1229984 in alcohol dehydrogenase 1B (ADH1B) and rs671 in aldehyde dehydrogenase 2 (ALDH2). Here we analyzed the relationships of the two genotypes with alcohol sensitivity, drinking behavior and problem drinking among older and younger men living in rural areas of Japan.

METHODS

The subjects were 718 Japanese men aged 63.3 ± 10.8 (mean ± SD), categorized into the older (≥65 years, n = 357) and younger (<65 years, n = 361) groups. Facial flushing frequency, drinking behavior and positive CAGE results were compared among the genotypes using Bonferroni-corrected χ(2) test and a multivariate logistic regression analysis adjusting for age, BMI and lifestyle factors.

RESULTS

The frequency of 'always' facial flushing among the ADH1B*1/*2 carriers was significantly lower than that among the ADH1B*2/*2 carriers in the older group (P < 0.01). The alcohol consumption (unit/day) in the ADH1B*1/*2 carriers tended to be higher compared with that in the ADH1B*2/*2 carriers among the older group (P = 0.050). In the younger group, no significant differences in alcohol sensitivity and drinking habits were generally found among the ADH1B genotypes. The ADH1B*1/*1 genotype tended to be positively associated with problem drinking in the older group (P = 0.080) but not in the younger group. The ALDH2 genotypes consistently and strongly affected the alcohol sensitivity, drinking behavior and problem drinking in both the younger and older group.

CONCLUSIONS

We for the first time observed a significant difference in alcohol sensitivity between ADH1B*1/*2 and ADH1B*2/*2 in older men aged 65 and above.

Impact of alcohol dehydrogenase gene 4 polymorphisms on esophageal squamous cell carcinoma risk in a Chinese population

Background

Esophageal squamous cell carcinoma (ESCC) is very common in China and is also one of the most common cancers worldwide. The purpose of this study was to examine the associations between genetic variants of various cancer-related genes and the risk of ESCC.

Methods

In this study, we first examined the association between 18 potentially disruptive genetic variants of 17 genes, including alcohol dehydrogenase 4 (ADH4) and checkpoint kinase 2 (CHEK2), and ESCC risk in a Hangzhou population of 617 patients matched with 534 controls. Among the 18 single nucleotide polymorphisms (SNPs), two were validated in a Jinan population of 540 patients matched with 550 controls.

Results

Sixteen SNPs in 15 genes, including CHEK2, did not have significantly different allele frequency distributions between ESCC patients and control subjects. A significantly increased risk of developing ESCC was revealed in subjects with the AA genotype of rs3805322 (ADH4) compared with those with the AG or GG genotype by unconditional univariate logistic regression analysis. Using a dominant model, the CC genotype of rs4822983 (CHEK2) had a marginally significant protective effect compared to the CT and TT genotypes. The association of ESCC risk with these two SNPs (rs3805322 and rs4822983) was further validated in a Jinan case-control set. Individuals with the ADH4 rs3805322 AA or AG genotype had ORs of 1.10 (95% CI = 0.81–1.49, P < 0.001) or 1.86 (95% CI = 1.33–2.59, P = 0.559), respectively, for developing ESCC compared with individuals with the GG genotype. CHEK2 rs4822983 CC carriers showed a marginally significantly decreased ESCC risk compared with those carrying the CT and TT genotypes in the validation set (95% CI = 0.61–1.01, P = 0.064). However, no evidence of interaction existed between the two SNPs and smoking or drinking in the Jinan case-control set.

Conclusions

In conclusion, this current study provides substantial evidence that genetic polymorphisms of rs3805322 in the ADH4 gene may be associated with an increased risk of developing ESCC in two Chinese Han populations. Future studies to address the biological function of this polymorphism in the development of ESCC are warranted.

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.

Association of alcohol dehydrogenase polymorphisms and life-style factors with excessive alcohol intake within the Spanish population (EPIC-Spain)

AIMS

To analyse associations between alcohol dehydrogenase (ADH) polymorphisms and alcohol intake in Spanish men and women.

DESIGN AND SETTINGS

We analysed the relationship between 21 genetic variants in ADH genes and excessive alcohol intake in both men and women. Single nucleotide polymorphisms (SNPs) were genotyped using a customized array and a sex-stratified analysis was performed.

MEASUREMENTS

Ethanol intake was calculated using a validated dietary history questionnaire.

PARTICIPANTS

Heavy consumers of alcohol (≥70 g/day in men, ≥42 g/day in women) (653 cases) and very low or non-consumers (<2 g/day) (880 controls) from the Spanish cohort of the European Prospective Investigation into Cancer (EPIC).

FINDINGS

We found statistically significant associations between alcohol intake and known life-style factors; namely, smoking and food energy intake (meat and fruit/seeds) in both men and women, as well as with physical activity in women and educational level in men. Additionally, we found that a non-synonymous coding SNP in ADH1B (rs1229984) is associated inversely with excessive alcohol intake in men [odds ratio (OR) = 0.19, 95% confidence interval (CI) = 0.11-0.33; P = 4.77E(-10) ) and women (OR = 0.48, 95% CI = 0.27-0.83; P = 0.0067). Furthermore, ADH6 rs3857224 was found associated with heavy alcohol intake in women (OR = 1.61, 95% CI = 1.21-2.14; P = 1.01E(-3) ), but not in men.

CONCLUSIONS

In the Spanish population, the single nucleotide polymorphism of alcohol dehydrogenase ADH1B, rs1229984, is associated inversely with alcohol intake in both men and women. Another polymorphism of ADH6, rs3857224, is associated with heavy alcohol intake in women.

Cloning and molecular evolution of the aldehyde dehydrogenase 2 gene (Aldh2) in bats (Chiroptera)

Old World fruit bats (Pteropodidae) and New World fruit bats (Phyllostomidae) ingest significant quantities of ethanol while foraging. Mitochondrial aldehyde dehydrogenase (ALDH2, encoded by the Aldh2 gene) plays an important role in ethanol metabolism. To test whether the Aldh2 gene has undergone adaptive evolution in frugivorous and nectarivorous bats in relation to ethanol elimination, we sequenced part of the coding region of the gene (1,143 bp, ~73 % coverage) in 14 bat species, including three Old World fruit bats and two New World fruit bats. Our results showed that the Aldh2 coding sequences are highly conserved across all bat species we examined, and no evidence of positive selection was detected in the ancestral branches leading to Old World fruit bats and New World fruit bats. Further research is needed to determine whether other genes involved in ethanol metabolism have been the targets of positive selection in frugivorous and nectarivorous bats.

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

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

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.

Diversification of the ADH1B gene during expansion of modern humans

A variant allele, ADH1B*48His, also known as ADH1B*2, at the human Alcohol Dehydrogenase 1B gene (ADH1B) is strongly associated with alcoholism in some populations and has an unusual geographic distribution. Strong evidence implies selection has increased the frequency of this allele in some East Asian populations but does not fully explain its geographic pattern. We have studied haplotypes of 10 single nucleotide polymorphisms (SNPs) and two short tandem repeat polymorphisms (STRPs) in the ADH1B region in 2,206 individuals from a worldwide set of populations. These SNPs and STRPs define nine common haplogroups most of which have distinct geographic patterns. The haplogroups H5 and H6, both with the derived ADH1B*48His allele, appear restricted to the Middle East and East Asia, respectively. The positively selected H7 is derived from H6 by a new regulatory region variant defining SNP rs3811801 restricted to East Asia. Age estimates of the haplogroups based on the STRPs also agree with the time of the migration events estimated by other studies. H7 is estimated to have expanded recently, around 2,800 years ago, and ancient DNA samples from North China confirm its presence about that time. The dating of the H7 expansion may help understand the selective force on the ADH1B gene.

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

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

Inverse association between toothbrushing and upper aerodigestive tract cancer risk in a Japanese population

BACKGROUND

Oral hygiene is attracting increasing attention as a potential risk factor for cancers. To investigate the association between toothbrushing frequency and upper aerodigestive tract (UADT) cancer, the authors conducted a large-scale case-control study.

METHODS

A total of 856 UADT cancer case participants and 2696 age- and sex-matched control subjects without cancer were included. Edentulous or participants with unknown frequency of toothbrushing or number of remaining teeth were excluded. Associations were assessed by odds ratios and 95% confidence intervals in logistic regression models with adjustment for potential confounders.

RESULTS

Compared with toothbrushing once per day, the adjusted odds ratio for brushing twice or more was 0.82 (95% confidence interval: 0.68, 0.99) whereas that for not brushing was 1.79 (0.79, 4.05). This association was observed especially in subjects who had a history of heavy smoking or drinking.

CONCLUSIONS

The authors suggest that toothbrushing could have a protective effect for UADT cancer.

Haplotype-based study of the association of alcohol-metabolizing genes with alcohol dependence in four independent populations

BACKGROUND

Ethanol is metabolized by 2 rate-limiting reactions: alcohol dehydrogenases (ADH) convert ethanol to acetaldehyde that is subsequently metabolized to acetate by aldehyde dehydrogenases (ALDH). Approximately 50% of East Asians have genetic variants that significantly impair this pathway and influence alcohol dependence (AD) vulnerability. We investigated whether variation in alcohol metabolism genes might alter the AD risk in four non-East Asian populations by performing systematic haplotype association analyses to maximize the chances of capturing functional variation.

METHODS

Haplotype-tagging SNPs were genotyped using the Illumina GoldenGate platform. Genotypes were available for 40 SNPs across the ADH genes cluster and 24 SNPs across the two ALDH genes in four diverse samples that included cases (lifetime AD) and controls (no Axis 1 disorders). The case control sample sizes were the following: Finnish Caucasians: 232, 194; African Americans: 267, 422; Plains American Indians: 226, 110; and Southwestern American (SW) Indians: 317, 72.

RESULTS

In all four populations, as well as HapMap populations, 5 haplotype blocks were identified across the ADH gene cluster: (i) ADH5-ADH4; (ii) ADH6-ADH1A-ADH1B; (iii) ADH1C; (iv) intergenic; (v) ADH7. The ALDH1A1 gene was defined by 4 blocks and ALDH2 by 1 block. No haplotype or SNP association results were significant after correction for multiple comparisons; however, several results, particularly for ALDH1A1 and ADH4, replicated earlier findings. There was an ALDH1A1 block 1 and 2 (extending from intron 5 to the 3' UTR) yin yang haplotype (haplotypes that have opposite allelic configuration) association with AD in the Finns driven by SNPs rs3764435 and rs2303317, respectively, and an ALDH1A1 block 3 (including the promoter region) yin yang haplotype association in SW Indians driven by 5 SNPs, all in allelic identity. The ADH4 SNP rs3762894 was associated with AD in Plains Indians.

CONCLUSIONS

The systematic evaluation of alcohol-metabolizing genes in four non-East Asian populations has shown only modest associations with AD, largely for ALDH1A1 and ADH4. A concentration of signals for AD with ALDH1A1 yin yang haplotypes in several populations warrants further study.

CYP2A13, ADH1B, and ADH1C gene polymorphisms and pancreatic cancer risk

OBJECTIVES

Pancreatic carcinoma etiology and molecular pathogenesis are weakly understood. Based on the assumption that genetic variation in carcinogen metabolism further modifies the risk of exposure-related cancers, we studied the association of polymorphisms in the tobacco carcinogen-metabolizing gene CYP2A13 (Arg101Stop) and the alcohol-metabolizing genes ADH1B (Arg48His) and ADH1C (Ile350Val) with pancreatic cancer risk.

METHODS

Polymorphisms were studied by allelic discrimination.

RESULTS

In a hospital-based case-control study, CYP2A13 variant alleles coding an inactive enzyme were found in 7 of 265 cancer-free controls and in none of 235 pancreatic carcinoma patients. Neither ADH1B or ADH1C polymorphisms alone nor their combinations showed a significant effect on pancreatic cancer risk.

CONCLUSIONS

The first study of the roles of CYP2A13, ADH1B, and ADH1C in pancreatic cancer etiology suggested that the controls may have a lower ability to bioactivate tobacco-derived procarcinogens than the cases.

The ADH1B Arg47His polymorphism in east Asian populations and expansion of rice domestication in history

Background

The emergence of agriculture about 10,000 years ago marks a dramatic change in human evolutionary history. The diet shift in agriculture societies might have a great impact on the genetic makeup of Neolithic human populations. The regionally restricted enrichment of the class I alcohol dehydrogenase sequence polymorphism (ADH1BArg47His) in southern China and the adjacent areas suggests Darwinian positive selection on this genetic locus during Neolithic time though the driving force is yet to be disclosed.

Results

We studied a total of 38 populations (2,275 individuals) including Han Chinese, Tibetan and other ethnic populations across China. The geographic distribution of the ADH1B*47His allele in these populations indicates a clear east-to-west cline, and it is dominant in south-eastern populations but rare in Tibetan populations. The molecular dating suggests that the emergence of the ADH1B*47His allele occurred about 10,000~7,000 years ago.

Conclusion

We present genetic evidence of selection on the ADH1BArg47His polymorphism caused by the emergence and expansion of rice domestication in East Asia. The geographic distribution of the ADH1B*47His allele in East Asia is consistent with the unearthed culture relic sites of rice domestication in China. The estimated origin time of ADH1B*47His allele in those populations coincides with the time of origin and expansion of Neolithic agriculture in southern China.

Impact of multiple alcohol dehydrogenase gene polymorphisms on risk of upper aerodigestive tract cancers in a Japanese population

Alcohol intake is positively associated with the risk of upper aerodigestive tract (UAT) cancer. The genes that encode alcohol-metabolizing enzymes, primarily alcohol dehydrogenases (ADH) and aldehyde dehydrogenases (ALDH), are polymorphic. In Caucasians, significant associations between polymorphisms in ADH1B (rs1229984) and ADH1C (rs698 and rs1693482), and UAT cancer have been observed, despite strong linkage disequilibrium among them. Moreover, UAT cancer was significantly associated with rs1573496 in ADH7, and not with rs1984362 in ADH4. However, little evidence is available concerning ADH4 or ADH7 polymorphisms in Asian populations. We conducted a matched case-control study to clarify the role of ADH polymorphisms in a Japanese population. Cases and controls were 585 patients with UAT cancer and 1,170 noncancer outpatients. Genotyping for ADHs and ALDH2 was done using TaqMan assays. Associations between polymorphisms and UAT cancer were assessed by odds ratios and 95% confidence intervals using conditional logistic regression models that adjusted for age, sex, smoking, drinking, and ALDH2. Adjusted odds ratios were significant for rs4148887 and rs3805322 in ADH4, rs1229984 in ADH1B, rs698 and rs1693482 in ADH1C, and rs284787, rs1154460, and rs3737482 in ADH7. We also observed that ADH7 rs3737482 and ADH4 rs4148887 had independently and statistically significant effects on UAT cancer. The magnitude of effect of these ADH polymorphisms was greater in subjects who were heavy drinkers, heavy smokers, and had esophageal cancer. These findings show that multiple ADH gene polymorphisms were associated with UAT cancer in this Japanese population. Further studies in various ethnicities are required.

Associations and interactions between SNPs in the alcohol metabolizing genes and alcoholism phenotypes in European Americans

BACKGROUND

Alcohol dependence is a major cause of morbidity and mortality worldwide and has a strong familial component. Several linkage and association studies have identified chromosomal regions and/or genes that affect alcohol consumption, notably in genes involved in the 2-stage pathway of alcohol metabolism.

METHODS

Here, we use multiple regression models to test for associations and interactions between 2 alcohol-related phenotypes and SNPs in 17 genes involved in alcohol metabolism in a sample of 1,588 European American subjects.

RESULTS

The strongest evidence for association after correcting for multiple testing was between rs1229984, a nonsynonymous coding SNP in ADH1B, and DSM-IV symptom count (p = 0.0003). This SNP was also associated with maximum number of drinks in 24 hours (p = 0.0004). Each minor allele at this SNP predicts 45% fewer DSM-IV symptoms and 18% fewer max drinks. Another SNP in a splice site in ALDH1A1 (rs8187974) showed evidence for association with both phenotypes as well (p = 0.02 and 0.004, respectively), but neither association was significant after accounting for multiple testing. Minor alleles at this SNP predict greater alcohol consumption. In addition, pairwise interactions were observed between SNPs in several genes (p = 0.00002).

CONCLUSIONS

We replicated the large effect of rs1229984 on alcohol behavior, and although not common (MAF = 4%), this polymorphism may be highly relevant from a public health perspective in European Americans. Another SNP, rs8187974, may also affect alcohol behavior but requires replication. Also, interactions between polymorphisms in genes involved in alcohol metabolism are likely determinants of the parameters that ultimately affect alcohol consumption.

Impact of alcohol consumption with polymorphisms in alcohol-metabolizing enzymes on pancreatic cancer risk in Japanese

The putative impact of alcohol on pancreatic cancer (PC) risk remains controversial. Here, we conducted a case-control study in Japanese to assess the impact of alcohol in conjunction with polymorphisms in alcohol-metabolizing enzymes. Cases were 160 patients with pancreatic cancer at Aichi Cancer Center, Nagoya, Japan. Two control groups of 800 age- and sex-matched non-cancer subjects each were independently selected. The impact of alcohol and polymorphisms in aldehyde dehydrogenase 2 (ALDH2) Glu504Lys, alcohol dehydrogenase (ADH) 1B His48Arg, and ADH1C Arg272Gln on PC risk was examined with multivariate analysis adjusted for potential confounders to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Results showed no independent impact of alcohol or genotype on PC risk except former drinking. To avoid reverse causation, former drinkers were excluded in further analyses. In the analysis of the combined effects of alcohol consumption and genotype, significant impact of alcohol was seen for those subjects with ALDH2 Lys+ allele, ADH1B His/His, or ADH1C Arg/Arg (trend P = 0.077, 0.003, or 0.020, respectively), each of which is associated with a high concentration or rapid production of acetaldehyde. Analysis of genotype combinations showed that ‘ever drinking’ with both ADH1B His/His and ALDH2 Lys + was the most potent risk factor for PC relative to ‘never drinkers’ with both ADH1B His/His and ALDH2 Glu/Glu [OR (95% CI); 4.09 (1.30–12.85)]. These results indicate that alcohol has an impact on PC risk when the effects of alcohol consumption and metabolism are combined. Acetaldehyde may be involved in the mechanisms underlying PC development.

Associations of ADH and ALDH2 gene variation with self report alcohol reactions, consumption and dependence: an integrated analysis

Alcohol dependence (AD) is a complex disorder with environmental and genetic origins. The role of two genetic variants in ALDH2 and ADH1B in AD risk has been extensively investigated. This study tested for associations between nine polymorphisms in ALDH2 and 41 in the seven ADH genes, and alcohol-related flushing, alcohol use and dependence symptom scores in 4597 Australian twins. The vast majority (4296) had consumed alcohol in the previous year, with 547 meeting DSM-IIIR criteria for AD. There were study-wide significant associations (P<2.3 x 10(-4)) between ADH1B-Arg48His (rs1229984) and flushing and consumption, but only nominally significant associations (P<0.01) with dependence. Individuals carrying the rs1229984 G-allele (48Arg) reported a lower prevalence of flushing after alcohol (P=8.2 x 10(-7)), consumed alcohol on more occasions (P=2.7 x 10(-6)), had a higher maximum number of alcoholic drinks in a single day (P=2.7 x 10(-6)) and a higher overall alcohol consumption (P=8.9 x 10(-8)) in the previous year than those with the less common A-allele (48His). After controlling for rs1229984, an independent association was observed between rs1042026 (ADH1B) and alcohol intake (P=4.7 x 10(-5)) and suggestive associations (P<0.001) between alcohol consumption phenotypes and rs1693482 (ADH1C), rs1230165 (ADH5) and rs3762894 (ADH4). ALDH2 variation was not associated with flushing or alcohol consumption, but was weakly associated with AD measures. These results bridge the gap between DNA sequence variation and alcohol-related behavior, confirming that the ADH1B-Arg48His polymorphism affects both alcohol-related flushing in Europeans and alcohol intake. The absence of study-wide significant effects on AD results from the low P-value required when testing multiple single nucleotide polymorphisms and phenotypes.

Ethnic related selection for an ADH Class I variant within East Asia

Background

The alcohol dehydrogenases (ADH) are widely studied enzymes and the evolution of the mammalian gene cluster encoding these enzymes is also well studied. Previous studies have shown that the ADH1B*47His allele at one of the seven genes in humans is associated with a decrease in the risk of alcoholism and the core molecular region with this allele has been selected for in some East Asian populations. As the frequency of ADH1B*47His is highest in East Asia, and very low in most of the rest of the world, we have undertaken more detailed investigation in this geographic region.

Methodology/Principal Findings

Here we report new data on 30 SNPs in the ADH7 and Class I ADH region in samples of 24 populations from China and Laos. These populations cover a wide geographic region and diverse ethnicities. Combined with our previously published East Asian data for these SNPs in 8 populations, we have typed populations from all of the 6 major linguistic phyla (Altaic including Korean-Japanese and inland Altaic, Sino-Tibetan, Hmong-Mien, Austro-Asiatic, Daic, and Austronesian). The ADH1B genotyping data are strongly related to ethnicity. Only some eastern ethnic phyla or subphyla (Korean-Japanese, Han Chinese, Hmong-Mien, Daic, and Austronesian) have a high frequency of ADH1B*47His. ADH1B haplotype data clustered the populations into linguistic subphyla, and divided the subphyla into eastern and western parts. In the Hmong-Mien and Altaic populations, the extended haplotype homozygosity (EHH) and relative EHH (REHH) tests for the ADH1B core were consistent with selection for the haplotype with derived SNP alleles. In the other ethnic phyla, the core showed only a weak signal of selection at best.

Conclusions/Significance

The selection distribution is more significantly correlated with the frequency of the derived ADH1B regulatory region polymorphism than the derived amino-acid altering allele ADH1B*47His. Thus, the real focus of selection may be the regulatory region. The obvious ethnicity-related distributions of ADH1B diversities suggest the existence of some culture-related selective forces that have acted on the ADH1B region.