Mutant ALDH2 Research Articles

Intake of Lactobacillus rhamnosus GG (LGG) fermented milk before drinking alcohol reduces acetaldehyde levels and duration of flushing in drinkers with wild-type and heterozygous mutant ALDH2: a randomized, blinded crossover controlled trial.

Alcohol consumption leads to acetaldehyde accumulation, especially in people with mutant aldehyde dehydrogenase 2 gene (ALDH2). Novel strategies to promote acetaldehyde detoxification are required to prevent alcohol-related toxicity. Probiotic bacteria such as Lactobacillus rhamnosus GG (LGG) were shown to have in vitro capacity to detoxify acetaldehyde. This randomized, blinded, placebo-controlled cross-over trial investigated the effect of LGG fermented milk in people with ALDH2 polymorphisms after moderate alcohol intake. Ten healthy wild-type and ten heterozygous mutant ALDH2 Thai men were block randomized into two groups. Each group consumed a different sequence of 150 mL fermented milk containing 108 CFU mL-1 LGG and lactic-acidified milk (placebo), followed by five glasses of beer (0.4 g ethanol per kg body weight), with a one-week wash-out. Consuming LGG fermented milk before alcohol reduced areas under the response curves of blood and salivary acetaldehyde in wild-type and heterozygous mutant ALDH2 individuals (p < 0.05 and p < 0.01, respectively). Interestingly, participants with mutant ALDH2 responded better than wild-type participants for salivary acetaldehyde (90% vs. 70%, p < 0.001). Their durations of flushing were reduced when consuming LGG milk. Regardless of ALDH2 status, 105 CFU mL-1 LGG was retained in saliva at least 3.5 h after milk consumption. In conclusion, intake of LGG fermented milk before drinking alcohol reduces blood and salivary acetaldehyde levels and duration of flushing in drinkers with wild-type and heterozygous mutant ALDH2. The addition of exogenous capacity to detoxify acetaldehyde using the probiotic product could be a potential strategy to promote the alleviation of exposure to reactive and carcinogenic acetaldehyde associated with alcohol drinking in individuals with defective ALDH2 enzyme.

Abstract 879: Aldehyde Dehydrogenase Activator 1 (Alda-1) Attenuates Coronary Endothelial Dysfunction-Mediated Cardiac Damage in ALDH2*2 Diabetic Mice

Background: Endothelial dysfunction plays a critical role in the pathogenesis of diabetic complications. Diabetes-mediated reactive aldehydes like 4-hydroxy-2-nonenal (4HNE) are associated with endothelial cell impairment. Aldehyde dehydrogenase (ALDH) 2, a mitochondrial enzyme which detoxifies 4HNE, protects heart function against diabetic cardiomyopathy. Nearly 600 million East Asians have a point mutation of ALDH2, termed as ALDH2*2, which causes an intrinsic low ALDH2 activity. Previously, we reported an aggravated coronary endothelial dysfunction in ALDH2*2 mutant knock-in mice (ALDH2*2 mice) with diabetes. Aldehyde dehydrogenase activator 1 (Alda-1) is the only known activator for both normal ALDH2 and mutant ALDH2*2. We hypothesized that Alda-1 could protect endothelial cells (ECs) from hyperglycemia induced coronary endothelial dysfunction in diabetic ALDH2*2 mice. Methods and Results: Diabetes was induced by streptozotocin injection (150 mg/kg) to ALDH2*2 mice. Alda-1 (10 mg/kg/d, DM-A) or vehicle (DM-V) was delivered through mini-pumps for 3 weeks after diabetes. We found an increased left ventricular pressure (59.9±18.7 vs 66.4±20.1 mmHg) and a decreased perfusion pressure (89.4±8.1 vs 83.6±12.1 mmHg) in Langendorff hearts from DM-A (DM-V vs DM-A, p&lt;0.05, respectively). In heart sections, CD31+ (127.2±22.3 vs 270.5±53.7 /mm 2 ) and eNOS+ cells (136.2±22.8 vs 366.7±33.6 /mm 2 ) were increased while apoptosis (1117.5±303.6 vs 727.1±254.8 /mm 2 ) and 4HNE+ (515.8±8.3 vs 181.7±72.5 /mm 2 ) cells were reduced in DM-A (DM-V vs DM-A, p&lt;0.05, respectively). Direct perfusion of 4HNE to Langendorff hearts from control ALDH2*2 mice (4HNE) increased perfusion pressure (Δ3.18±0.5 vs Δ36.6±7.7 mmHg), arteriole closure (8.3±0.4 vs 39.8±3.7 /mm 2 ), and decreased eNOS+ cells (2877.1±117.3 vs 37.5±5.6 /mm 2 ) (Sham vs 4HNE, p&lt;0.05). One-day Alda-1 (10 mg/kg) pre-treatment before 4HNE perfusion (A-4HNE) decreased perfusion pressure (Δ7.1±1.7 mmHg), number of closed arterioles (22.4±4.8 /mm 2 ), and increased eNOS+ (878.0±121.3 /mm 2 ) cells (4HNE vs A-4HNE, p&lt;0.05, respectively). Conclusion: Alda-1 protects hyperglycemia mediated 4HNE induced coronary endothelial dysfunction and thereby cardiac tissue in ALDH2*2 diabetic mice.

Abstract 4360: ALDH2 and the TGF-β/SMAD3 adaptor, Sptbn1 suppress hepatic steatosis and obesity

Abstract Background: Previously we have demonstrated that TGF-β-deficient mutants derived from the loss of Smad3 and the Smad adaptor β2SP (Sptbn1) phenocopy a human cancer stem cell syndrome, are exquisitely sensitive to alcohol, with dysregulation DNA damage repair and have raised levels of aldehyde dehydrogenase (ALDH2). Moreover, β2SP and β2SP/Smad3 mutant mice develop multiple liver abnormalities that include steatosis, chronic hepatitis, inflammation, and cancer. ALDH2 is a key intermediate enzyme for aldehyde and alcohol metabolism. We, therefore, hypothesized that disruption of TGF-β signaling combined with ALDH2 deficiency would increase the susceptibility of liver cancer. Methods: Aldh2 knockout mice were intercrossed with Sptbn1 heterozygous knockout mice to explore the role of Aldh2 and Sptbn1 in liver steatosis and liver cancer. Conditional knockout of Sptbn1 mice was generated by the intercross of Albumin-Cre mice with mice carrying Loxp sites flanked exons of Sptbn1. Sptbn1 conditional mice were fed with high-fat diet or chow diet. Further analysis included blood lipid panel analysis and tissue profiles including western and RNA analysis, lipidomics and metabolomics analysis of liver tissues from the mutant mice and wild-type controls. Results: Interestingly, we found that Aldh2-/-Sptbn1+/- mice on a normal diet demonstrated early signs of truncal obesity. Within 6 months of age, we observed a greater than 23% increase in body weight, with predominantly abdominal fat accumulation in Aldh2-/-Sptbn1+/- mice compared to Aldh2-/- mice or wild type (WT) mice (Aldh2-/-Sptbn1+/- vs Aldh2-/- or WT, p&amp;lt;0.05). A marked increase in zone 3 hepatic micro and macro-steatosis with some inflammation was observed in liver tissues of mutant Aldh2-/-Sptbn1+/- mice as well as the conditional Sptbn1 knockout (Alb-Cre+Sptbn1F/+) mice in a high-fat diet. In addition to significant increased blood glucose levels in Aldh2-/-Sptbn1+/- mice compared with Aldh2-/- mice (165±23 VS 135±13, p&amp;lt;0.05), further analysis revealed that the fatty liver phenotype accompanied with abnormal expression of genes related to glucose uptake, metabolisms and homeostasis as demonstrated by decrease of glucose transporter and increased expression of Ceramide which is known to promote insulin resistance. Moreover, we also observed disruption of lipid metabolism as demonstrated by significantly increased serum and liver triglyceride and cholesterol ester levels in Aldh2-/-Sptbn1+/- mice. Conclusions: Our data suggest that the TGF-β pathway plays an important role in maintaining normal glucose metabolism homeostasis and patients with SPTBN1 and ALDH2 defects may have increased susceptibility to obesity as well as fatty liver (NASH), and cancer. Citation Format: Shuyun Rao, Sobia Zaidi, Wilma Jogunoori, Shoujun Gu, Jon White, Bibhuti Mishra, Chu-Xia Deng, Patricia Latham, Lopa Mishra. ALDH2 and the TGF-β/SMAD3 adaptor, Sptbn1 suppress hepatic steatosis and obesity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4360.

An integrative bioinformatics pipeline to demonstrate the alteration of the interaction between the ALDH2*2 allele with NAD+ and Disulfiram.

Alcohol use disorder (AUD) is a multifactorial psychiatric behavior disorder. Disulfiram is the first approved drug by the Food and Drug Administration for alcohol-dependent patients, which targets the ALDH2 enzyme. Several genes are known to be involved in alcohol metabolism; mutations in any of these genes are known to be associated with AUD. The E504K mutation in the ALDH2 of the precursor protein or the E487K of the mature protein (E504K/E487K; ALDH2*2 allele) is carried by approximately 8% of the world population. In this study, we aimed to test the known inactive allele ALDH2*2, to validate the use of our extensive computational pipeline (in silico tools, molecular modeling, and molecular docking) for testing the interaction between the ALDH2*2 allele, NAD+, and Disulfiram. In silico predictions showed that the E504K variant of ALDH2 to be pathogenic and destabilizing with the maximum number of prediction in silico tools. Consequently, we studied the effect of this mutation mainly on the interaction between NAD+ -E504K and Disulfiram-E504K complexes using molecular docking technique, and molecular dynamics (MD) analysis. From the molecular docking analysis with NAD+ , we observed that the interaction affinity of the NAD+ decreases with the impact of E504K variant. On the other hand, the drug Disulfiram showed similar interaction in both the native and mutant ALDH2 proteins. Further, the comprehensive MD analysis predicted that the E504K destabilizes the protein and influences the NAD+ and Disulfiram interactions. Our findings reveal that the interaction of NAD+ to the protein is disturbed by the E504K/E487K variant whereas the drug Disulfiram has a similar effect as both native ALDH2 and ALDH2 bearing E504K/E487K variant. This study provides a platform to understand the effect of E504K/E487K on the molecular interaction with NAD+ and Disulfiram.

Contribution of ALDH2 polymorphism to alcoholism-associated hypertension.

Chronic alcohol intake is considered as an independent lifestyle factor that may influence the risk of a number of cardiovascular anomalies including hypertension. In healthy adults, binge drinking and chronic alcohol ingestion lead to the onset and development of hypertension although the precise mechanism(s) remains obscure. Although oxidative stress and endothelial injury have been postulated to play a major contributing role to alcoholism-induced hypertension, recent evidence depicted a rather unique role for the genotype of the acetaldehyde-metabolizing enzyme mitochondrial aldehyde dehydrogenase (ALDH2), which is mainly responsible for detoxifying ethanol consumed, in alcoholism-induced elevation of blood pressure. Genetic polymorphism of ALDH2 in human results in altered ethanol pharmacokinetic properties and ethanol metabolism, leading to accumulation of the ethanol metabolite acetaldehyde following alcohol intake. The unfavorable consequence of the ALDH2 variants is believed to be governed by the accumulation of the ethanol metabolite acetaldehyde. Presence of the mutant or inactive ALDH2*2 gene often results in an increased risk of hypertension in human. Such association between blood pressure and ALDH2 enzymatic activity may be affected by the interplay between gene and environment, such as life style and ethnicity. The aim of this mini-review is to summarize the possible contribution of ALDH2 genetic polymorphism in the onset and development of alcoholism-related development of hypertension. Furthermore, the double-edged sword of ALDH2 gene and genetic polymorphism in alcoholism and alcoholic tissue damage and relevant patents will be discussed.

Tandem repeat polymorphism of the CYP2E1 gene: an association study with esophageal cancer and lung cancer.

Cytochrome P-450 (CYP) enzymes have been shown to play important roles in chemical carcinogenesis. Reports have indicated that polymorphism in CYP1A1, CYP1A2, CYP2A6, CYP2E1, and CYP2D6 are associated with an altered risk of developing cancers of the lung, bladder, liver, and colon. CYP2E1 plays an important role in alcohol metabolism and participates in the metabolic activation of various carcinogens, such as N-nitrosodimethylamine. Recently, we found repeated sequences that consist of four alleles (A1, A2, A3, and A4) and six genotypes (A1/A2, A2/A2, A2/A3, A2/A4, A3/A4 and A4/A4) of the CYP2E1 gene. In the present study, we investigated whether these polymorphisms are associated with lung cancer and esophageal cancer. DNA was isolated from blood samples of 192 healthy control subjects, 85 patients with lung cancer, and 82 patients with esophageal cancer in Japanese males. DNA samples were amplified by polymerase chain reaction in the 5'-flanking region of the CYP2E1 gene and in exon 12 in the ALDH2 gene. The tandem repeat polymorphisms were examined using DNA fragment analysis. Missense mutations in exon 12 of the ALDH2 gene were examined using fluorescence-based single strand conformational change polymorphism analysis. Written informed consent was obtained from all the subjects. In the CYP2E1 gene 5'-flanking region polymorphism, patients with esophageal cancer showed significantly higher frequency of the A4/A4 genotype compared with the control subjects (p = 0.02), but no difference was found in patients with lung cancer. The frequencies of the mutant ALDH2*2 allele were significantly higher in patients with esophageal cancer (27.7%) than in healthy control subjects (7.3%; p< 0.0001; habitual alcohol drinkers). The distribution of genotypes and allele frequencies of the tandem repeats of the 5'-flanking region of the CYP2E1 gene was significantly different in patients with esophageal cancer.

Aldehyde dehydrogenase 2 genotypes, alcohol flushing symptoms and drinking patterns in Thai men

The drinking behavior, alcohol-induced facial flushing and ALDH2 genotypes were determined in 283 Thai men comprising 85 who were alcohol-dependent, 62 hazardous/harmful drinkers and 136 non-drinkers or infrequent drinkers. A structured interview questionnaire, containing the ‘tri-level’ method and the Alcohol-Use Disorders and Associated Disabilities Schedule, was used to determine the quantity of drinking and the number of alcohol-related adverse experiences. The study revealed the mutant ALDH2*2 allele in 44 (15.5%) subjects. The risks of being alcohol-dependent and of having hazardous/harmful drinking were lower in individuals with heterozygous ALDH2*1/*2, compared with homozygous ALDH2*1/*1 [relative probability ratios (95% CI) 0.14 (0.05–0.41) and 0.23 (0.08–0.61), respectively]. Eighty percent of those who were heterozygous and 28% of those who were homozygous ALDH2*1 reported flush symptoms after drinking alcohol. Twenty-nine percent of homozygous ALDH2*1 individuals, but only 9% of heterozygous subjects, drank almost everyday (24–30 days/month). Similarly, higher percentages of people drinking beyond the safety limit (>60 g/day) and having alcohol-related problems were observed in homozygous ALDH2*1 compared with heterozygous individuals: 32% vs. 5% and 27% vs. 12%, respectively. Overall, the study supports the role of the mutant ALDH2*2 allele in preventing high alcohol consumption and the development of alcohol dependence in a Thai population.

Deficiency in a mitochondrial aldehyde dehydrogenase increases vulnerability to oxidative stress in PC12 cells.

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) plays a major role in acetaldehyde detoxification. The alcohol sensitivity is associated with a genetic deficiency of ALDH2. We have previously reported that this deficiency influences the risk for late-onset Alzheimer's disease. However, the biological effects of the deficiency on neuronal cells are poorly understood. Thus, we obtained ALDH2-deficient cell lines by introducing mouse mutant Aldh2 cDNA into PC12 cells. The mutant ALDH2 repressed mitochondrial ALDH activity in a dominant negative fashion, but not cytosolic activity. The resultant ALDH2-deficient transfectants were highly vulnerable to exogenous 4-hydroxy-2-nonenal, an aldehyde derivative generated by the reaction of superoxide with unsaturated fatty acid. In addition, the ALDH2-deficient transfectants were sensitive to oxidative insult induced by antimycin A, accompanied by an accumulation of proteins modified with 4-hydroxy-2-nonenal. Thus, these findings suggest that mitochondrial ALDH2 functions as a protector against oxidative stress.

Chaperonin GroESL mediates the protein folding of human liver mitochondrial aldehyde dehydrogenase in Escherichia coli

An efficient bacterial expression system for the human mitochondrial aldehyde dehydrogenase (ALDH2) was developed using co-overexpression of heat shock chaperone gene GroESL. On the basis of the ALDH2 amino acid sequence and cDNA sequences a full-length cDNA encoding wild-type ALDH2 was cloned from a human liver library. A mutant-type ALDH2 (ALDH2 2) was developed using site-directed mutagenesis of the ALDH2 cDNA and also cloned. Both types of ALDH2 cDNA were subcloned for expression in Escherichia coli ( E. coli), recombinant ALDH2 and ALDH2 2 were successfully expressed as soluble active enzymes following co-expression with a second plasmid construct producing GroES and GroEL, E. coli chaperonin proteins. Purified wild-type ALDH2 and mutant ALDH2 2 had a K m for acetaldehyde of 0.65 and 25.73 μM, respectively. Co-expression of ALDH2 with ALDH2 2 in the presence of E. coli chaperonins produced a soluble enzyme with a K m for acetaldehyde of 8.79 μM, suggesting that the product was a heteromer. Mitochondrial matrix hsp60 and hsp10 chaperonins are then thought to act on imported ALDH2 and are essential for accurate protein folding and multisubunit formation. Protein–protein interactions between ALDH2s and various chaperones were investigated using the yeast two-hybrid system. The wild-type and mutant-type enzymes strongly interacted with each other and GroEL and ALDH2s also interacted but only weakly. Chaperone hsp10 also interacted with hsp60 and ALDH2 1 and ALDH2 2, but again the interactions were weak ones.

Tandem Repeat Polymorphism of the CYP2E1 Gene: An Association Study With Esophageal Cancer and Lung Cancer

Background Cytochrome P‐450 (CYP) enzymes have been shown to play important roles in chemical carcinogenesis. Reports have indicated that polymorphism in CYP1A1, CYP1A2, CYP2A6, CYP2E1, and CYP2D6 are associated with an altered risk of developing cancers of the lung, bladder, liver, and colon. CYP2E1 plays an important role in alcohol metabolism and participates in the metabolic activation of various carcinogens, such as N‐nitrosodimethylamine. Recently, we found repeated sequences that consist of four alleles (A1, A2, A3, and A4) and six genotypes (A1/A2, A2/A2, A2/A3, A2/A4, A3/A4, and A4/A4) of the CYP2E1 gene. In the present study, we investigated whether these polymorphisms are associated with lung cancer and esophageal cancer.Methods DNA was isolated from blood samples of 192 healthy control subjects, 85 patients with lung cancer, and 82 patients with esophageal cancer in Japanese males. DNA samples were amplified by polymerase chain reaction in the 5′‐flanking region of the CYP2E1 gene and in exon 12 in the ALDH2 gene. The tandem repeat polymorphisms were examined using DNA fragment analysis. Missense mutations in exon 12 of the ALDH2 gene were examined using fluorescence‐based single strand conformational change polymorphism analysis. Written informed consent was obtained from all the subjects.Results In the CYP2E1 gene 5′‐flanking region polymorphism, patients with esophageal cancer showed significantly higher frequency of the A4/A4 genotype compared with the control subjects (p= 0.02), but no difference was found in patients with lung cancer. The frequencies of the mutant ALDH2*2 allele were significantly higher in patients with esophageal cancer (27.7%) than in healthy control subjects (7.3%;p &lt; 0.0001; habitual alcohol drinkers).Conclusions The distribution of genotypes and allele frequencies of the tandem repeats of the 5′‐flanking region of the CYP2E1 gene was significantly different in patients with esophageal cancer.

Why can't Chinese Han drink alcohol? Hepatitis B virus infection and the evolution of acetaldehyde dehydrogenase deficiency

An aldehyde-dehydrogenase (ALDH2) deficiency is a biological curb on excess alcohol-drinking. This enzyme deficiency is very common amongst Oriental people while it is relatively rare for most other populations. We observe that there is good geographical correlation between the prevalence of the mutant ALDH2*2 alleles and hepatitis B virus (HBV) infections. Populations that demonstrate a high ALDH2*2 prevalence are all located in HBV-endemic areas. Further, studies have shown that HBV and alcohol drinking exhibit a synergistic effect upon liver cirrhosis and cancer. A shorter life span for those with HBV infection and heavy alcohol consumption may result in a selection of the ALDH2*2 gene. We postulate that there may be patterns of evolutionary adaptation for ALDH2 deficiency in certain HBV-endemic areas and that these adaptations can produce differences in human alcohol-drinking capability.

Tandem Repeat Polymorphism of the CYP2E1 Gene: An Association Study With Esophageal Cancer and Lung Cancer

Background Cytochrome P-450 (CYP) enzymes have been shown to play important roles in chemical carcinogenesis. Reports have indicated that polymorphism in CYP1A1, CYP1A2, CYP2A6, CYP2E1, and CYP2D6 are associated with an altered risk of developing cancers of the lung, bladder, liver, and colon. CYP2E1 plays an important role in alcohol metabolism and participates in the metabolic activation of various carcinogens, such as N-nitrosodimethylamine. Recently, we found repeated sequences that consist of four alleles (A1, A2, A3, and A4) and six genotypes (A1/A2, A2/A2, A2/A3, A2/A4, A3/A4, and A4/A4) of the CYP2E1 gene. In the present study, we investigated whether these polymorphisms are associated with lung cancer and esophageal cancer. Methods DNA was isolated from blood samples of 192 healthy control subjects, 85 patients with lung cancer, and 82 patients with esophageal cancer in Japanese males. DNA samples were amplified by polymerase chain reaction in the 5′-flanking region of the CYP2E1 gene and in exon 12 in the ALDH2 gene. The tandem repeat polymorphisms were examined using DNA fragment analysis. Missense mutations in exon 12 of the ALDH2 gene were examined using fluorescence-based single strand conformational change polymorphism analysis. Written informed consent was obtained from all the subjects. Results In the CYP2E1 gene 5′-flanking region polymorphism, patients with esophageal cancer showed significantly higher frequency of the A4/A4 genotype compared with the control subjects (p= 0.02), but no difference was found in patients with lung cancer. The frequencies of the mutant ALDH2*2 allele were significantly higher in patients with esophageal cancer (27.7%) than in healthy control subjects (7.3%;p < 0.0001; habitual alcohol drinkers). Conclusions The distribution of genotypes and allele frequencies of the tandem repeats of the 5′-flanking region of the CYP2E1 gene was significantly different in patients with esophageal cancer.

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Association of aldehyde dehydrogenase 2gene polymorphism with multiple oesophageal dysplasia in head and neck cancer patients

BACKGROUNDMultiple occurrences of oesophageal dysplasia are frequently observed in head and neck cancer patients, and closely associated with alcohol consumption. Acetaldehyde, the first metabolite of ethanol, is thought to play...

Aldehyde dehydrogenase (ALDH) 2 associates with oxidation of methoxyacetaldehyde; in vitro analysis with liver subcellular fraction derived from human and Aldh2 gene targeting mouse

A principal pathway of 2-methoxyethanol (ME) metabolism is to the toxic oxidative product, methoxyacetaldehyde (MALD). To assess the role of aldehyde dehydrogenase (ALDH) in MALD metabolism, in vitro MALD oxidation was examined with liver subcellular fractions from Japanese subjects who carried three different ALDH2 genotypes and Aldh2 knockout mice, which were generated in this study. The activity was distributed in mitochondrial fractions of ALDH2*1/*1 and wild type ( Aldh2+/+) mice but not ALDH2*1/*2, *2/*2 subjects or Aldh2 homozygous mutant ( Aldh2−/−) mice. These data suggest that ALDH2 is a key enzyme for MALD oxidation and ME susceptibility may be influenced by the ALDH2 genotype.

Biological Markers of Alcoholism With Respect to Genotypes of Low‐Km Aldehyde Dehydrogenase (ALDH2) in Japanese Subjects

Although the mutant low-Km acetaldehyde dehydrogenase (ALDH2) allele (ALDH2(2)) with reduced capacity to metabolize acetaldehyde offers biological protection against alcoholism and subsequent alcohol-induced organ damage in many individuals, a significant proportion of individuals with heterozygote of the normal and mutant ALDH2 gene (ALDH2(1)/2(2)) consume excessive amounts of alcohol. Indeed, it has been postulated that habitual drinkers with ALDH2(1)/2(2) may be at a higher risk for alcoholic liver disease than those with ALDH2(1)/2(1). In this study, we determined how representative biological markers of alcoholism (gamma-glutamyltransferase [GGT], carbohydrate-deficient transferrin [CDT], and the mean corpuscular volume of erythrocytes [MCV]) differ with respect to the ALDH2 genotypes in Japanese habitual drinkers. We obtained genomic DNA samples from 227 Japanese men with various drinking habits. ALDH2 genotypes were determined by allele-specific polymerase chain reaction. GGT, CDT, and MCV were determined and compared between ALDH2(1)/2(1) and ALDH2(1)/2(2) habitual drinkers who consumed more than 66 g of alcohol per day for more than 5 years. We measured CDT by anion-exchange chromatography followed by turbidity immunoassay by using a commercially available assay kit (Axis %CDT TIA). CDT levels were comparable between the two groups. GGT activities were significantly greater in ALDH2(1)/2(1) than in ALDH2(1)/2(2) habitual drinkers (81 +/- 85 vs. 53 +/- 40 IU/liters, p < 0.02). MCV values, on the other hand, were significantly larger in ALDH2(1)/2(2) than in ALDH2(1)/2(1) subjects (98.2 +/- 5.8 vs. 95.8 +/- 4.2 fl, p = 0.02). When we used elevation of either CDT or GGT to detect habitual drinking in ALDH2(1)/2(1) and 2(1)/2(2) subjects, the sensitivities were 57% and 46%, respectively. CDT levels were similar between habitual drinkers with normal aspartate aminotransferase levels and those with elevated levels. GGT and MCV, but not CDT, differ with respect to the ALDH2 genotypes in Japanese male habitual drinkers. ALDH2 genotypes should be considered when interpreting data on biological markers of alcoholism.

Polymorphism in ALDH2-genotype in Japanese men and the alcohol-blood pressure relationship

Aldehyde dehydrogenase with a low Michaelis constant (Km), ALDH2, is a major enzyme involved in the conversion of acetaldehyde, a toxic metabolite of ethanol, into acetic acid in the liver. Inherited deficiency of ALDH2 activity is found in half of Japanese, and is characterized by "Oriental flushing" after alcohol consumption. The aim of the present study is to evaluate the influence of the genetic polymorphism in alcohol metabolism on the sensitivity to the pressor effect of alcohol. Genotypes of ALDH2 were determined in 403 middle-aged Japanese men using genomic DNA extracted from white blood cells. Two hundred and forty-three (60%) of the subjects were shown to be homozygotes for the normal ALDH2 gene, 25 (6%) of the subjects were homozygotes for the mutant ALDH2 gene, and the remaining 135 (33%) were heterozygotes. None of the homozygotes for the mutant gene drank enough to show the pressor effect of alcohol. Elevations of blood pressure associated with increasing alcohol consumption or with elevations of serum gamma-glutamyl transpeptide (GTP) level were not different between the other two ALDH2-genotypes. It can be concluded that polymorphism in the ALDH2-genotype found in Japanese men does not affect the individual sensitivity to the pressor effect of alcohol.

Polymorphism of alcohol and aldehyde dehydrogenase genes and alcoholic cirrhosis in Chinese patients

Liver alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), the principal enzymes responsible for the oxidation of ethanol, are polymorphic at the ADH2, ADH3 and ALDH2 loci in human beings. Our previous studies have shown that, compared with nonalcoholic individuals, Chinese alcoholic patients without liver disease had significantly lower frequencies of the ADH2*2 and ADH3*1 alleles, which encode high maximum velocity β2- and γ1-ADH subunits, respectively, as well as a lower frequency of the ALDH2*2 allele, which encodes an enzymatically inactive subunit. The data strongly suggest that genetic variation in both ADH and ALDH may influence drinking behavior and the risk of alcoholism developing through acetaldehyde formation. To further investigate the possible role of acetaldehyde in the pathogenesis of alcoholic liver disease, we determined the ADH and ALDH genotype frequencies in patients with alcohol-related cirrhosis (n = 27), viral hepatitis-related cirrhosis (n = 29) and gastric and duodenal ulcer without relevance to alcohol (n = 30). We developed a new restriction fragment length polymorphism method to genotype the mutant and normal ALDH2 alleles by using polymerase chain reaction–directed mutagenesis, which proved to be simpler and faster than the conventional detection methods that use hybridization with allele-specific oligonucleotide probes. We found that the frequencies of the alleles ADH2*2 (57), ADH3*1 (78) and ALDH2*2 (9) in the alcoholic cirrhotic patients were significantly lower than those in the healthy controls and in the patients with cirrhosis from viral hepatitis and with gastric and duodenal ulcer. No significant differences in the allele frequencies of these three genes between the alcoholic cirrhotic patients and the alcohol-dependent subjects without severe liver injury were found, although the alcoholic cirrhosis group tended to have a higher incidence of ALDH2*1/*2 heterozygotes (5 of 27) than did the alcohol-dependent group (6 of 50). The results confirm previous studies that the ADH2*2, ADH3*1 and ALDH2*2 genes can affect predisposition to alcoholism in Chinese patients and suggest that the mutant ALDH2*2 gene may influence susceptibility to alcoholic cirrhosis. (Hepatology 1994;19:360–366).

Polymorphism of alcohol and aldehyde dehydrogenase genes and alcoholic cirrhosis in chinese patients

Liver alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), the principal enzymes responsible for the oxidation of ethanol, are polymorphic at the ADH2, ADH3 and ALDH2 loci in human beings. Our previous studies have shown that, compared with nonalcoholic individuals, Chinese alcoholic patients without liver disease had significantly lower frequencies of the ADH2*2 and ADH3*1 alleles, which encode high maximum velocity beta 2- and gamma 1-ADH subunits, respectively, as well as a lower frequency of the ALDH2*2 allele, which encodes an enzymatically inactive subunit. The data strongly suggest that genetic variation in both ADH and ALDH may influence drinking behavior and the risk of alcoholism developing through acetaldehyde formation. To further investigate the possible role of acetaldehyde in the pathogenesis of alcoholic liver disease, we determined the ADH and ALDH genotype frequencies in patients with alcohol-related cirrhosis (n = 27), viral hepatitis-related cirrhosis (n = 29) and gastric and duodenal ulcer without relevance to alcohol (n = 30). We developed a new restriction fragment length polymorphism method to genotype the mutant and normal ALDH2 alleles by using polymerase chain reaction-directed mutagenesis, which proved to be simpler and faster than the conventional detection methods that use hybridization with allele-specific oligonucleotide probes. We found that the frequencies of the alleles ADH2*2 (57%), ADH3*1 (78%) and ALDH2*2 (9%) in the alcoholic cirrhotic patients were significantly lower than those in the healthy controls and in the patients with cirrhosis from viral hepatitis and with gastric and duodenal ulcer.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol and aldehyde dehydrogenase polymorphisms and alcoholism

The alcohol-flush reaction occurs in Asians who inherit the mutant ALDH2*2 allele that produces an inactive aldehyde dehydrogenase enzyme. In these individuals, high blood acetaldehyde levels are believed to be the cause of the unpleasant symptoms that follow drinking. We measured the alcohol elimination rates and intensity of flushing in Chinese subjects in whom the alcohol dehydrogenase ADH2 and ALDH2 genotypes were determined. We also correlated ADH2, ADH3, and ALDH2 genotypes with drinking behavior in 100 Chinese men. We discovered that ADH2*2 and ADH3*1, alleles that encode the high activity forms of alcohol dehydrogenase, as well as the mutant ALDH2*2 allele were less frequent in alcoholics than in controls. The presence of ALDH2*2 was associated with slower alcohol metabolism and the most intense flushing. In those homozygous for ALDH2*1, the presence of two ADH2*2 alleles correlated with slightly faster alcohol metabolism and more intense flushing, although a great deal of variability in the latter was noted.