SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Using the polymerase chain reaction to amplify genomic DNA from hair roots, we have examined the mitochondrial aldehyde dehydrogenase (ALDH2) genotypes of 28 individuals from the South American Mapuche Indians. We have determined that individuals from this population previously reported to lack (ALDH2) activity do not show the presence of the inactive (ALDH2(2] allele frequently found in Orientals.
Genetic variation at two polymorphic alcohol dehydrogenase loci, ADH2 and ADH3, and at the polymorphic mitochondrial aldehyde dehydrogenase locus, ALDH2, may influence the risk of developing alcoholism by modulating the rate of elimination of ethanol and the rate of formation and elimination of acetaldehyde. Populations differ in allele frequencies at these loci. We determined the genotypes at all three of these loci in Atayal natives of Taiwan. The frequencies of ADH2*2, ADH3*1, and ALDH2*1 alleles (0.91, 0.99, and 0.95, respectively) were significantly higher among the Atayal than among a predominantly Han Chinese population from Taiwan. Among the Atayal, the group with alcohol use disorders (alcohol dependence and alcohol abuse) had a significantly lower frequency of the ADH2*2 allele (0.82) than those without alcohol use disorders (0.91). The ADH2*2 allele encodes the beta 2 subunit; isozymes containing beta 2 subunits oxidize alcohol faster in vitro than the beta 1 beta 1 isozyme encoded by ADH2*1. Thus, the simplest explanation for these data is that individuals with a beta 2 isozymes have a higher rate of ethanol oxidation, which is a deterrent to alcohol abuse and dependence in some individuals. The Atayal with alcohol use disorders also had a lower frequency of ALDH2*2 than the controls; this allele is known to be responsible for the alcohol-flush reaction among Asians, and thereby deters drinking.
The effects of the genotype of alcohol dehydrogenase-2 (ADH2) and mitochondrial aldehyde dehydrogenase (ALDH2) on drinking behavior were investigated in a population of 451 Japanese. Although the ALDH2*2 allele had a significant inhibitory effect on alcohol consumption, hence on drinking problems, the apparent association was not confirmed between ADH2 genotype and overall drinking patterns for either males or females. However, the frequency of the ADH2*2 allele was significantly lower in male Japanese classified as alcoholic on the basis of the Kurihama Alcoholism Screening Test than in nonalcoholic males. These results corroborate a previous study that revealed a significantly lower ADH2*2 allele frequency in hospitalized Japanese alcoholics than in the general population. Together, these studies suggest that the ALDH2*2 allele has an inhibitory effect on drinking behavior, irrespective of the level of alcohol consumption, whereas the effect of the ADH2 polymorphism only becomes apparent in individuals with higher alcohol consumption, such as alcoholics.
BACKGROUND: Alcohol consumption is one of the major risk factors of the upper aerodigestive tract (UADT) cancers, and combined cancers are frequently discovered in the patients with UADT cancer. The association between esophageal cancer and alcohol-related metabolizing enzymes is well studied, but only a few examinations about the association between head and neck cancer and the enzymes were performed. METHODS: Fifty-two patients with UADT cancer (head and neck cancer in 25, esophageal cancer in 19, and multiple cancers in 8) were examined in the alcohol habit and in the polymorphisms of aldehyde dehydrogenase 2 (ALDH2) and cytochrome P-4502E1. RESULTS: Patients with multiple cancers had significantly higher ethanol consumption than the other two groups (p < 0.001). The frequency of ALDH2*1/2*2 heterozygote was significantly lower (p = 0.009) in patients with head and neck cancer (5/25) than patients with esophageal cancer (11/19). The allele frequency of P-4502E1 did not show a significant difference between the groups (p = 0.700). CONCLUSIONS: These results demonstrated the difference in the frequency of ALDH2 heterozygote between the patients with esophageal cancer and patients with head and neck cancer.
Ethanol oxidation in Kupffer cells was investigated by measuring 14C-acetate formation from 14C-ethanol, and the role of aldehyde dehydrogenase 2 (ALDH2) in this process was also examined. Formation of 14C-acetate from 20 mM of 14C-ethanol was significantly increased in medium-containing Kupffer cells (9,003 +/- 2,066 cpm/5 x 10(6) cells), compared with medium containing no cells (1,826 +/- 46 cpm, p < 0.01), or containing acid-killed Kupffer cells (1,629 +/- 210 cpm, p < 0.01). Ethanol formation was significantly attenuated when 20 and 200 microM cyanamide or 2 microM disulfiram were given. Reverse transcriptase-polymerase chain reaction demonstrated that Kupffer cells carry mRNA for ALDH2. These findings indicate that Kupffer cells can oxidize ethanol to acetate. ALDH2 may participate in this process, especially in the conversion of acetaldehyde to acetate.
The full-length DNAs for two Saccharomyces cerevisiae aldehyde dehydrogenase (ALDH) genes were cloned and expressed in Escherichia coli. A 2,744-bp DNA fragment contained an open reading frame encoding cytosolic ALDH1, with 500 amino acids, which was located on chromosome XVI. A 2,661-bp DNA fragment contained an open reading frame encoding mitochondrial ALDH5, with 519 amino acids, of which the N-terminal 23 amino acids were identified as the putative leader sequence. The ALDH5 gene was located on chromosome V. The commercial ALDH (designated ALDH2) was partially sequenced and appears to be a mitochondrial enzyme encoded by a gene located on chromosome XV. The recombinant ALDH1 enzyme was found to be essentially NADP dependent, while the ALDH5 enzyme could utilize either NADP or NAD as a cofactor. The activity of ALDH1 was stimulated two- to fourfold by divalent cations but was unaffected by K+ ions. In contrast, the activity of ALDH5 increased in the presence of K+ ions: 15-fold with NADP and 40-fold with NAD, respectively. Activity staining of isoelectric focusing gels showed that cytosolic ALDH1 contributed 30 to 70% of the overall activity, depending on the cofactor used, while mitochondrial ALDH2 contributed the rest. Neither ALDH5 nor the other ALDH-like proteins identified from the genomic sequence contributed to the in vitro oxidation of acetaldehyde. To evaluate the physiological roles of these three ALDH isoenzymes, the genes encoding cytosolic ALDH1 and mitochondrial ALDH2 and ALDH5 were disrupted in the genome of strain TWY397 separately or simultaneously. The growth of single-disruption delta ald1 and delta ald2 strains on ethanol was marginally slower than that of the parent strain. The delta ald1 delta ald2 double-disruption strain failed to grow on glucose alone, but growth was restored by the addition of acetate, indicating that both ALDHs might catalyze the oxidation of acetaldehyde produced during fermentation. The double-disruption strain grew very slowly on ethanol. The role of mitochondrial ALDH5 in acetaldehyde metabolism has not been defined but appears to be unimportant.
A NAD-dependent enzyme that catalyzes the oxidation of retinal to retinoic acid has been purified to homogeneity from bovine kidney. The procedures used in the purification included ion-exchange chromatography on DEAE-Sepharose, affinity chromatography on Affi-gel blue and chromatography on a Mono-Q anion-exchange column. On the Mono-Q column, the enzyme aldehyde dehydrogenase (ALDH) resolved into two activity peaks designated as ALDH1 and ALDH2. The enzymes ALDH1 and ALDH2 were purified about 114- and 65-fold, respectively. Gel filtration chromatography of the partially purified native enzyme on Sephacryl S-200 HR exhibited a molecular mass of about 108 kDa. Electrophoresis of the purified enzymes under nondenaturing conditions showed a single protein band. However, sodium dodecyl sulfate--polyacrylamide gel electrophorsis indicated three protein bands in the 55, 30, and 22 kDa molecular mass regions. Both enzymes exhibited a broad substrate specificity oxidizing a wide variety of aliphatic and aromatic aldehydes. The ALDH1 enzyme had a pI of 7.45 and exhibited a low Km (6.37 microM) for retinal, while the ALDH2 enzyme was found to have very low Km for acetaldehyde (0.98 microM). Based on its kinetic properties, it is suggested that the ALDH1 enzyme may be the primary enzyme for oxidizing retinal to retinoic acid in bovine kidney.
Asian case-control studies have shown a strong relationship between the development of squamous cell carcinoma (SCC) of the esophagus and alcohol consumption combined with inactive aldehyde dehydrogenase-2 (ALDH2*1/*2), less-active alcohol dehydrogenase-1B (ADH1B*1/*1), high mean corpuscular volume (MCV), and self-reported facial flushing in response to alcohol. However, little is known about whether these risk factors prospectively influence cancer development in cancer-free alcoholics. Between 1993 and 2005, 808 Japanese alcoholic men diagnosed as cancer-free by an initial endoscopic screening examination received follow-up examinations ranging from 1 to 148 months (median, 31 months) later, and SCC of the upper aerodigestive tract was diagnosed in 53 of them (esophagus in 33 and oropharyngolarynx in 30). Cox proportional hazards analysis showed that the age-adjusted relative hazard for SCC was 11.55 [95% confidence interval (95% CI), 5.73-23.3] in ALDH2*1/*2 heterozygotes compared with ALDH2*1/*1 homozygotes, 2.02 (95% CI, 1.02-4.02) in ADH1B*1/*1 homozygotes compared with ADH1B*1/*2 heterozygotes or *2/*2 homozygotes, 2.64 (95% CI, 1.49-4.67) in patients with flushing compared with those who had never experienced flushing, 2.91 (95% CI, 1.63-5.20) in those with an MCV >or= 106 compared with those with an MCV < 106, 2.52 (95% CI, 1.22-5.22) in those who smoked >or=30 cigarettes per day compared with those who smoked 0 to 19 cigarettes per day, 7.26 (95% CI, 3.99-13.23) in those with esophageal dysplasia compared with those without distinct iodine-unstained lesions >or=5 mm, and 0.28 (95% CI, 0.09-0.85) in those with body mass index >or= 23.2 (highest quartile) compared with those with body mass index < 19.0 (lowest quartile). These predictors are useful for selecting appropriately patients for careful follow-up examinations.
Ethanol is considered to activate the brain reward system by increasing the release of an endogenous opioid receptor ligand, beta-endorphin. The polymorphism A118G in the mu-opioid receptor gene (OPRM1) causes the amino acid change Asn40Asp and has been reported to affect the affinity of the ligand for the receptor. The association of this polymorphism with the vulnerability to alcohol dependence has been studied in many populations, but not yet in Japanese people. In the present study, we compared the frequencies of the polymorphism OPRM1 A118G between patients with alcohol dependence and healthy control subjects living in a Japanese provincial prefecture. We also genotyped a polymorphism, G1510A, in the acetaldehyde dehydrogenase 2 gene (ALDH2), in which the A allele causes poor metabolism of acetaldehyde, a major metabolite of alcohol. Both OPRM1 118G and ALDH2 1510G were significantly associated with alcohol dependence. These results suggest that OPRM1 118G in addition to ALDH2 1510G might be one of the risk factors for alcohol dependence in Japanese people.
OBJECTIVE: Two alcohol dehydrogenase genes (ADH2 and ADH3 on chromosome 4) and one aldehyde dehydrogenase gene (ALDH2 on chromosome 12) exhibit functional polymorphisms. The goal of this study was to determine whether any associations exist between the ADH2, ADH3, and ALDH2 polymorphisms and alcohol dependence in a group of Native Americans. An additional goal was to determine if any associations exist between these polymorphisms and the endophenotype, maximum number of drinks ever consumed in a 24-hour period. METHOD: Mission Indian adults (N=340) were recruited for participation from reservations in southern California. Each participant completed an interview with the Semi-Structured Assessment for the Genetics of Alcoholism. A blood sample was collected from each participant for genotyping at the ALDH2, ADH2, and ADH3 loci. RESULTS: Sixty percent of all participants (72% of men and 53% of women) met lifetime DSM-III-R criteria for alcohol dependence. A significant difference in the ADH2 allele distributions was found between alcohol-dependent and non-alcohol-dependent participants. Those with alcohol dependence were significantly less likely to have the ADH2*3 allele (odds ratio=0.28) and significantly more likely to have the ADH2*1 allele (odds ratio=2.00) than those who were not alcohol dependent. Individuals with ADH2*3 reported a lower number of maximum drinks ever consumed in a 24-hour period, compared to those without this allele. CONCLUSIONS: These results are consistent with genetic linkage studies showing protective associations for alcohol dependence and related behavior on chromosome 4 and suggest that ADH2 polymorphisms may account for these findings. These results also highlight the utility of evaluating protective factors in populations with high rates of alcohol dependence.
OBJECTIVE: The authors examined the genetic polymorphisms of alcohol dehydrogenase 2 and 3 (ADH2 and ADH3) and aldehyde dehydrogenase (ALDH2) in patients diagnosed as having Cloninger's type I or type II alcoholism. METHOD: Seventy-two alcoholic men and 38 nonalcoholic, healthy men were tested for the distribution of genotypes and alleles of ADH2, ADH3, and ALDH2. Forty-eight of the alcoholic men had type I alcoholism, and 24 had type II alcoholism. RESULTS: The frequencies of ADH2*1 and ADH3*2 alleles were significantly higher in men with type II alcoholism than in men with type I alcoholism and healthy men. The frequency of the ALDH2*1 allele was significantly higher in men with alcohol dependence than in healthy men. CONCLUSIONS: The genetic characteristics of alcohol dehydrogenases in men with type I alcoholism were similar to those of healthy men, and the genetic characteristics of aldehyde dehydrogenase in men with type I alcoholism were similar to those of men with type II alcoholism. These findings suggest that the genetic characteristics of alcohol metabolism in type I alcoholism fall between nonalcoholism and type II alcoholism.
A strong protection against the development of alcoholism is exerted by a point mutation in the gene coding for low Km aldehyde dehydrogenase (ALDH), i.e. ALDH2. We report a non-radioactive method for determining the common and atypical human mitochondrial aldehyde dehydrogenase (ALDH2) genotypes. This method is based on the fact that the base change (G-->A) in Exon 12 of the ALDH2 gene abolishes an Eco57 I restriction site (CTGAAG-->CTAAAG). A GC-clamp attached oligonucleotide was designed to yield a 176 base pair product by the polymerase chain reaction. After amplification, the resulting fragment containing the normal nucleotide sequence is cut by Eco57 I into two segments (131 base pairs + 45 base pairs) while the fragment containing the mutated sequence remains intact (176 base pairs). These are visualized by staining with ethidium bromide on agarose gels without blotting, hybridization or autoradiography.
A case control study on male primary hepatocellular carcinoma(HCC) and hepatitis B or C virus and some potential risk factors, e.g. blood transfusion, aldehyde dehydrogenase 2(ALDH2) genotype and drinking habits, was performed using two controls, i.e. a hospital control(HC) and a community control(CC) in Fukuoka and Saga Prefectures. Cases were obtained from the Second Department of Internal Medicine, Kurume University Hospital. The HCs were obtained from inpatients of two general hospitals in Kurume and the CCs were randomly sampled from the Kurume citizens being matched with age and sex to each case. Based on the HCs, odds ratios(ORs) of developing male HCC were statistically significant due to HBsAg or anti-HCV antibody positive status. Some discrepancies were observed between the two controls, i.e. higher proportions of past histories of diabetes or hypertension, of ALDH2 typical homozygote(ALDH2(1)/ALDH2(1)), and of heavy drinkers among the HCs, suggesting slight deviation of the HCs from the CCs in alcohol related aspects. Although ORs regarding accumulated amount of alcohol intake by age 40 based on the HCs were insignificant, two of the three corresponding ORs based on the CCs were statistically significant. Judging from alcohol related aspects between the two controls, the ORs for alcohol based on the HCs seems to be underestimated.
Although cigarette smoking is one major determinant of lung carcinogenesis, not all smokers develop cancer. This phenomenon is due to individual variation in genetic susceptibility to carcinogens, nutrition, and lifestyle. Previous studies have shown that genetic polymorphism of metabolic enzymes and plasma micronutrients are associated with lung cancer risk. DNA adducts may serve as a molecular dosimeter for exposure to carcinogens. In this cross-sectional study, we analyzed the blood samples of 158 subjects to evaluate the effects of polymorphisms of cytochrome P450 1A1 (CYP1A1), glutathione S-transferase M1 (GSTM1), T (GSTT), N-acetytransferase 2 (NAT2), and aldehyde dehydrogenase 2 (ALDH2) as well as the effects of plasma beta-carotene and alpha-tocopherol on lymphocyte DNA adducts measured by 32P-postlabeling analysis. The DNA adduct level of smokers (mean +/- SD, 1.26 +/- 0.79/10(8) nucleotides) was significantly higher than that of nonsmokers (0.87 +/- 0.33, P = 0.007). Smokers with CYP1A1 minor homozygotes and GSTM1 null genotypes had a significantly higher level of DNA adducts than those without (P = 0.027 for homozygotes, P = 0.049 for heterozygotes). Smokers with NAT2 minor homozygotes also tended to have a higher DNA adduct level than those with heterozygotes and wild alleles, but the difference was not statistically significant. The DNA adduct level of smokers with ALDH2 heterozygotes was significantly higher than that of smokers with minor homozygotes (P = 0.045). When smokers were divided into "high" and "low" groups according to mean level of plasma beta-carotene or alpha-tocopherol, in the low beta-carotene group, the subjects with CYP1A1 minor homozygotes had higher DNA adduct levels than those with other CYP1A1 genotypes. Smokers with GSTT null genotype and high beta-carotene tended to have a higher DNA adduct level than those with GSTT present and high beta-carotene (P = 0.07), and those with GSTT null genotype and low beta-carotene (P = 0.07). There was weak correlation between DNA adduct level and number of cigarettes smoked per day in the low plasma beta-carotene group (r = 0.28, n = 36, p < 0.1). These results suggested that polymorphisms of CYP1A1, GSTM1, T, NAT2, and ALDH2, and plasma beta-carotene may modulate the level of DNA adducts.
An individual genotype of aldehyde dehydrogenase 2 was observed using nail clippings by an improved method consisting of DNA extraction with guanidium thiocyanate, genomic DNA amplification by non-isotopic polymerase chain reaction, and gel electrophoresis of the DNA fragment. The results were consistent with those obtained using the corresponding peripheral blood samples. The individual phenotype was also determined by the Tokyo-University ALDH2-Phenotype Screening Test. Both types of ALDH2 were observed in 120 healthy Japanese and 48% were the typical or normal homozygote, 43% were the heterozygote, and 9% were the atypical or mutant homozygote of ALDH2. Among 57 individuals of both sexes with the typical homozygote, 88% were the phenotype of a non-flusher. Similarly 76% of the 63 heterozygote/atypical homozygotes had the phenotype of a flusher.
AIM: Hypermethylation of the promoter of the hMLH1 gene, which plays an important role in mismatch repair during DNA replication, occurs in more than 30% of human gastric cancer tissues. The purpose of this study was to investigate the effects of environmental factors, genetic polymorphisms of major metabolic enzymes, and microsatellite instability on hypermethylation of the promoter of the hMLH1 gene in gastric cancer. METHODS: Data were obtained from a hospital-based, case-control study of gastric cancer. One hundred and ten gastric cancer patients and 220 age- and sex-matched control patients completed a structured questionnaire regarding their exposure to environmental risk factors. Hypermethylation of the hMLH1 gene promoter, polymorphisms of the GSTM1, GSTT1, CYP1A1, CYP2E1, ALDH2 and L-myc genes, microsatellite instability and mutations of p53 and Ki-ras genes were investigated. RESULTS: Both smoking and alcohol consumption were associated with a higher risk of gastric cancer with hypermethylation of the hMLH1 gene promoter. High intake of vegetables and low intake of potato were associated with increased likelihood of gastric cancer with hypermethylation of the hMLH1 gene promoter. Genetic polymorphisms of the GSTM1, GSTT1, CYP1A1, CYP2E1, ALDH2, and L-myc genes were not significantly associated with the risk of gastric cancer either with or without hypermethylation in the promoter of the hMLH1 gene. Hypermethylation of the hMLH1 promoter was significantly associated with microsatellite instability (MSI): 10 of the 14 (71.4%) MSI-positive tumors showed hypermethylation, whereas 28 of 94 (29.8%) the MSI-negative tumors were hypermethylated at the hMLH1 promoter region. Hypermethylation of the hMLH1 gene promoter was significantly inversely correlated with mutation of the p53 gene. CONCLUSION: These results suggest that cigarette smoking and alcohol consumption may influence the development of hMLH1-positive gastric cancer. Most dietary factors and polymorphisms of GSTM1, GSTT1, CYP1A1, CYP2E1, ALDH2, and L-myc genes are not independent risk factors for gastric cancer with hypermethylation of the hMLH1 promoter. These data also suggest that there could be two or more different molecular pathways in the development of gastric cancer, perhaps involving tumor suppression mechanisms or DNA mismatch repair.
AIM: To develop a simple and accurate method for quantifying 8-isoprostane in plasma by employing a combination of two-step solid-phase extraction of samples and a commercially available ELISA kit, and by this method to examine the effects of drinking and smoking habits against the levels of plasma 8-isoprostane in healthy Japanese volunteers. METHODS: Plasma 8-isoprostane was extracted with ODS gel suspension followed by NH(2) Sep-Pak column. The 8-isoprostane fractions were assayed using a commercially available ELISA kit. We measured plasma 8-isoprostane levels in 157 healthy Japanese volunteers divided into three groups (64 non-habitual drinkers, 56 moderate drinkers and 37 habitual drinkers) according to their alcohol consumption per week. Genotypes of aldehyde dehydrogenase 2 (ALDH2) were also determined to investigate the plasma 8-isoprostane levels with reference to drinking habits. In addition, the plasma 8-isoprostane levels of 96 non-smokers and 61 smokers from the same subjects were compared. RESULTS: Our method fulfilled all the requirements for use in routine clinical assays with respect to sensitivity, intra- and inter-assay reproducibility, accuracy and dynamic assay range. Significant increases of plasma 8-isoprostane levels were observed in female habitual drinkers when compared with those of non-habitual drinkers (t = 5.494, P<0.0001) as well as moderate drinkers (t = 3.542, P<0.005), and 8-isoprostane levels were also significantly different between ALDH2*2/1 and ALDH2*1/1 in the female habitual drinkers (t = 6.930, P<0.0001), suggesting that excessive drinking of alcohol may increase oxidization stress, especially in females. On the contrary, no significant difference of the plasma 8-isoprostane levels was observed between non-smokers and smokers. CONCLUSION: Our present method was proved to be a simple and accurate tool for measuring plasma 8-isoprostane. However, the clinical utility of plasma 8-isoprostane for drinking and smoking habits was limited since elevated 8-isoprostane levels were observed in female heavy drinkers, and no association was found between smokers and nonsmokers.
Genotypes of alcohol dehydrogenase 2(ADH2) and aldehyde dehydrogenase 2(ALDH2) were detected by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in order to acquire and compare the distributions of polymorphisms about ADH2 and ALDH2 in five Chinese nationalities. The results were as follows: (1) Heterozygous genotype of ADH2 and homozygous genotype of ALDH2 are the two dominant ones in all the five nationalities. (2) The distributions of the two genes 'polymorphisms have certain differences among some nationalities.