Comparison of genetic polymorphisms ofCYP2E1,ADH2, andALDH2genes involved in alcohol metabolism in Koreans and four other ethnic groups

Hepatic, Extrahepatic and Extracellular Vesicle Cytochrome P450 2E1 in Alcohol and Acetaminophen-Mediated Adverse Interactions and Potential Treatment Options

Alcohol and several therapeutic drugs, including acetaminophen, are metabolized by cytochrome P450 2E1 (CYP2E1) into toxic compounds. At low levels, these compounds are not detrimental, but higher sustained levels of these compounds can lead to life-long problems such as cytotoxicity, organ damage, and cancer. Furthermore, CYP2E1 can facilitate or enhance the effects of alcohol-drug and drug-drug interactions. In this review, we discuss the role of CYP2E1 in the metabolism of alcohol and drugs (with emphasis on acetaminophen), mediating injury/toxicities, and drug-drug/alcohol-drug interactions. Next, we discuss various compounds and various nutraceuticals that can reduce or prevent alcohol/drug-induced toxicity. Additionally, we highlight experimental outcomes of alcohol/drug-induced toxicity and potential treatment strategies. Finally, we cover the role and implications of extracellular vesicles (EVs) containing CYP2E1 in hepatic and extrahepatic cells and provide perspectives on the clinical relevance of EVs containing CYP2E1 in intracellular and intercellular communications leading to drug-drug and alcohol-drug interactions. Furthermore, we provide our perspectives on CYP2E1 as a druggable target using nutraceuticals and the use of EVs for targeted drug delivery in extrahepatic and hepatic cells, especially to treat cellular toxicity.

Estimating the time of last drinking from blood ethyl glucuronide and ethyl sulphate concentrations

The determination of length of time from the last drinking is critical for cases like drunk driving, sexual assault victims, and also postmortem suspected poisoning cases. The study was aimed to established a method of estimating the time of last drinking through the pharmacokinetic study of conjugation metabolites of alcohol in blood after a single oral dose. Twenty-six volunteers (14 males) consumed alcohol with food at a fixed dose of 0.72 g/kg after fasting for 12 h. Five milliliters of blood were collected 120 h after the start of drinking, and all samples were analyzed with headspace-gas chromatography and high-performance liquid chromatography–tandem mass spectrometry. The time point of last drinking was estimated through the relationship between the concentration ratio of ethyl glucuronide to ethyl sulphate and the length of time after drinking. Pharmacokinetic parameters were analyzed by a pharmacokinetic software DAS according to the non-compartment model. A good correlation model was obtained from the relationship between concentration ratio of ethyl glucuronide to ethyl sulphate in blood and the time of alcohol use, and the margin of error was mostly lower than 10%. The time of maximum concentration, maximum concentration, and elimination half-life of ethyl glucuronide in blood were 4.12 ± 1.07 h, 0.31 ± 0.11 mg/L and 2.56 ± 0.89 h; the time of maximum concentration, maximum concentration, and elimination half-life of ethyl sulphate in blood were 3.02 ± 0.70 h, 0.17 ± 0.04 mg/L, and 2.04 ± 0.76 h. The study established a potential method to estimate the length of time after a moderate oral dose, and provided pharmacokinetic parameters of ethyl glucuronide and ethyl sulphate in Chinese population.

Genome-wide association study of alcohol dependence in male Han Chinese and cross-ethnic polygenic risk score comparison

Alcohol-related behaviors are moderately heritable and have ethnic-specific characteristics. At present, genetic studies for alcohol dependence (AD) in Chinese populations are underrepresented. We are the first to conduct a genome-wide association study (GWAS) for AD using 533 male alcoholics and 2848 controls of Han Chinese ethnicity and replicate our findings in 146 male alcoholics and 200 male controls. We then assessed genetic effects on AD characteristics (drinking volume/age onset/Michigan Alcoholism Screening Test (MAST)/Barratt Impulsiveness Scale (BIS-11)), and compared the polygenic risk of AD in Han Chinese with other populations (Thai, European American and African American). We found and validated two significant loci, one located in 4q23, with lead SNP rs2075633*ADH1B (P_discovery = 6.64 × 10^-16) and functional SNP rs1229984*ADH1B (P_discovery = 3.93 × 10^-13); and the other located in 12q24.12-12q24.13, with lead SNP rs11066001*BRAP (P_discovery = 1.63 × 10^-9) and functional SNP rs671*ALDH2 (P_discovery = 3.44 × 10^-9). ADH1B rs1229984 was associated with MAST, BIS_total score and average drinking volume. Polygenic risk scores from the Thai AD and European American AD GWAS were significantly associated with AD in Han Chinese, which were entirely due to the top two loci, however there was no significant prediction from African Americans. This is the first case-control AD GWAS in Han Chinese. Our findings demonstrate that these variants, which were highly linked with ALDH2 rs671 and ADH1B rs1229984, were significant modulators for AD in our Han Chinese cohort. A larger replication cohort is still needed to validate our findings.

Hazardous Alcohol Consumption and the Risk of Hearing Impairment in Adults Based on the Korean National Health and Nutrition Survey: A Retrospective Study

BACKGROUND AND OBJECTIVES

To investigate the relationship between hearing impairment and alcohol drinking patterns in South Korean adults.

SUBJECT AND METHODS

Data collection was performed by Korean National Health and Nutrition Survey from January 1 to December 31, 2012. Data analyses were performed from February 20 to March 3, 2018. Data from 3,860 adults 20 years of age or older without a history of malignancy or chronic otitis media in the Korean National Health and Nutrition Survey 2012 database who participated in the health questionnaires, and who had available results from otologic examinations that included pure tone audiogram, were included. Pure-tone average hearing thresholds were calculated at 500, 1,000, 2,000, and 4,000 Hz. Hearing loss was defined as a pure-tone average >40 dB in one or both ears. The Alcohol Use Disorder Identification Test was used to evaluate drinking statuses of subjects. Data were analyzed using the complex-sample χ2 -test of independence and a complex-sample logistic regression analysis.

RESULTS

Of the 29,954,319 individuals in the weighted cross-sectional study population, 15,106,040 (50.4%) were men and 14,848,098 (49.6%) were women. A total of 8.1% of men and 7% of women had hearing impairment. The degrees of drinking with appropriate, risky, and hazardous drinking habits were 58.2, 32.1, and 9.7% among men; and 76.4, 12.5, and 11.1% among women, respectively. Among men, the odds ratio of hearing loss increased by 2.506 times when comparing hazardous and appropriate drinking (confidence interval, 1.083 to 5.800, p=0.002). Moderate alcohol consumption (≤2 drinks per day) was not protective for hearing in either group.

CONCLUSIONS

As hazardous drinking tends to coexist with hearing impairment in men, appropriate prevention and intervention strategies should be emphasized. A longitudinal study to investigate harmful drinking and the mechanism of hearing loss should be performed.

Aldehyde dehydrogenase 2 rs671G>A polymorphism and ischemic stroke risk in Chinese population: a meta-analysis

Introduction: Recently, molecular epidemiological studies have suggested that aldehyde dehydrogenase 2 (ALDH2) rs671 G>A polymorphism may be a risk factor for ischemic stroke (IS). However, the results reported have not been consistent. Methods: We conducted the meta-analysis to explore the precise association between ALDH2 rs671 G>A polymorphism and IS risk. Five online databases were searched and the relative studies were reviewed from inception to October 1, 2018. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated in each genetic model of the general and subgroup. Furthermore, the heterogeneity, accumulative analyses, sensitivity analyses and publication bias were calculated simultaneously. Results: Overall, nine case-control studies involving 6,129 subjects were included in this meta-analysis. All studies were focused on the Chinese population and some significant associations were found between ALDH2 rs671 G>A polymorphism and IS risk (A vs G: OR=1.29, 95% CI=1.01-1.65, P=0.04, I²=78.2%; AA vs GG: OR=1.86, 95% CI=1.27-2.21, P<0.01, I²=11.3%; AA vs GG + GA: OR=1.67, 95% CI=1.27-2.19, P<0.01, I²=0%). Some significant and similar results were also observed in the subgroup analysis. Conclusion: Our meta-analysis indicates that the ALDH2 rs671 G>A polymorphism may play an important role in the occurrence of IS by reducing the activity of ALDH2 and interfering with the metabolic processes involving acetaldehyde.

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

Background

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

Material/Methods

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

Results

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

Conclusions

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

Calcium/calmodulin-dependent protein kinase IV gene polymorphisms in Korean alcohol-dependent patients

INTRODUCTION

A relationship between alcohol dependence (AD) and calcium/calmodulin-dependent protein kinase IV (CAMKIV) has been reported in a whole genome study of Korean AD patients. The purpose of the present study is to compare the frequency of CAMKIV genotypes and alleles between AD and control subjects in Korea.

METHODS

The present study includes 281 AD patients and 139 control subjects. Seven single nucleotide polymorphism of CAMKIV gene known to show significant separation ratio in Asians were searched in SNP database and previous studies related to CAMKIV gene. Polymerase chain reaction and restriction fragment length polymorphism techniques were used to analyze genotype of CAMKIV gene SNPs.

RESULTS

Major TT genotype and T allele frequencies of rs 25917 in AD patients were significantly higher than those of control subjects (genotype frequency, p=0.002; allele frequency, p=0.001). Major CC genotype and C allele frequencies of rs 117590959 in AD patients were also significantly higher than those of control subjects (genotype frequency, p<0.001; allele frequency, p=0.001). Major genotypes of rs25917 (p=0.002, odd ratio: 3.13, 95% CI: 1.54-6.38) and rs11790959 (p=0.002, odd ratio: 3.22, 95% CI: 1.52-6.81) showed significantly higher odds ratios associated with AD than minor genotypes in logistic regression.

DISCUSSION

These results suggest that CAMKIV might be a candidate AD gene. Further research is needed to determine the precise relationship between CAMKIV and AD and the function of each SNP.

The Pivotal Role of Aldehyde Toxicity in Autism Spectrum Disorder: The Therapeutic Potential of Micronutrient Supplementation

Autism spectrum disorder (ASD) is characterized by social and communication impairments as well as by restricted, repetitive patterns of behavior and interests. Genomic studies have not revealed dominant genetic errors common to all forms of ASD. So ASD is assumed to be a complex disorder due to mutations in hundreds of common variants. Other theories argue that spontaneous DNA mutations and/or environmental factors contribute to as much as 50% of ASD. In reviewing potential genetic linkages between autism and alcoholism, it became apparent that all theories of ASD are consistent with aldehyde toxicity, in which endogenous and exogenous aldehydes accumulate as a consequence of mutations in key enzymes. Aldehyde toxicity is characterized by cell-localized, micronutrient deficiencies in sulfur-containing antioxidants, thiamine (B1), pyridoxine (B6), folate, Zn²⁺, possibly Mg²⁺, and retinoic acid, causing oxidative stress and a cascade of metabolic disturbances. Aldehydes also react with selective cytosolic and membrane proteins in the cell of origin; then some types migrate to damage neighboring cells. Reactive aldehydes also form adducts with DNA, selectively mutating bases and inducing strand breakage. This article reviews the relevant genomic, biochemical, and nutritional literature, which supports the central hypothesis that most ASD symptoms are consistent with symptoms of aldehyde toxicity. The hypothesis represents a paradigm shift in thinking and has profound implications for clinical detection, treatment, and even prevention of ASD. Insight is offered as to which neurologically afflicted children might successfully be treated with micronutrients and which children are unlikely to be helped. The aldehyde toxicity hypothesis likely applies to other neurological disorders.

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.

A cross-sectional analysis of the relationship between daily alcohol consumption and serum adiponectin levels among adults aged 40 years or more in a rural area of Korea

BACKGROUND/OBJECTIVES

Light-to-moderate alcohol consumption has been proposed to raise serum adiponectin levels, but this view is controversial. There is little information on the effect of heavy drinking. The aim of this study was to examine the relationship between alcohol consumption and serum adiponectin levels in healthy Koreans.

SUBJECTS/METHODS

The design of the study was cross-sectional, using data from the Korean Multi-Rural Communities Cohort Study (MRCohort), which is a part of the Korean Genome Epidemiology Study (KoGES). The subjects were 1542 individuals (635 men and 907 women) aged ≥ 40 years who were recruited in Yangpyeong-Gun, Kyunggi province, South Korea, in 2005 and 2006. Daily alcohol consumption was calculated from average frequency of alcohol consumption and the amount of alcohol consumed per occasion using a structured questionnaire and serum adiponectin levels were measured.

RESULTS

Although adiponectin levels appeared to be higher in those consuming moderate levels of alcohol than in nondrinkers, the difference was not statistically significant. Heavy drinking (≥ 90.0 g/day) was significantly related to reduced serum adiponectin levels (P=0.003), although the significance of the relationship was reduced after adjusting for potential confounders (P=0.061) such as age, waist/hip ratio, blood pressure, fasting blood glucose, current smoker, higher education, protein intake, vitamin C intake and vitamin E intake in men. The relation seemed to be stronger in individuals consuming alcohol in the form of takju (Korean rice wine; P=0.022).

CONCLUSIONS

Heavy alcohol drinking (≥ 90.0 g/day) may be related to lower serum adiponectin levels in Korean men.

Confirmation and generalization of an alcohol-dependence locus on chromosome 10q

Several genome scans on alcohol dependence (AD) and AD-related traits have been published. In this article, we present the results of a genome-wide linkage scan on AD and several related traits in 322 European-American (EA) families, and results of additional analysis in 335 African-American (AA) families that were the subject of a previous report. All families were initially ascertained for cocaine and/or opioid dependence. Non-parametric linkage analysis in the EA sample revealed suggestive linkages on chromosomes 7 (LOD=2.1 at 82.8 cM, p=0.0009) and 10 (LOD=3.0 at 137.7 cM, p=0.0001). The chromosome 10 linkage peak is 20 cM distal from a genome-wide significant linkage peak we observed previously in the AA sample. Parametric linkage analysis on chromosome 10 (assuming a recessive model, 80% penetrance, disease allele frequency=0.3) resulted in LOD scores of 2.7 at 136.7 cM and 1.9 at 121.7 cM in the EA and AA samples, respectively, with a combined sample genome-wide significant LOD score of 4.1 at 131.7 cM. To reduce heterogeneity of the AD phenotype, we also assessed linkage of chromosome 10 markers with the presence of alcohol withdrawal symptoms, one of the seven components of the DSM-IV diagnosis of AD. Suggestive evidence for linkage was observed in both populations with only 5 cM separating the location of the peak LOD scores despite a loss of power due to a smaller number of families informative for this trait. Results of our study confirm a chromosome 10 risk locus for AD in two genetically distinct populations and suggest that this locus may correspond more precisely to a specific component of the disorder.

Alcohol and acetaldehyde in public health: from marvel to menace

Alcohol abuse is a serious medical and social problem. Although light to moderate alcohol consumption is beneficial to cardiovascular health, heavy drinking often results in organ damage and social problems. In addition, genetic susceptibility to the effect of alcohol on cancer and coronary heart disease differs across the population. A number of mechanisms including direct the toxicity of ethanol, its metabolites [e.g., acetaldehyde and fatty acid ethyl esters (FAEEs)] and oxidative stress may mediate alcoholic complications. Acetaldehyde, the primary metabolic product of ethanol, is an important candidate toxin in developing alcoholic diseases. Meanwhile, free radicals produced during ethanol metabolism and FAEEs are also important triggers for alcoholic damages.

Alcohol abuse in pregnant women: effects on the fetus and newborn, mode of action and maternal treatment

Offspring of mothers using ethanol during pregnancy are known to suffer from developmental delays and/or a variety of behavioral changes. Ethanol, may affect the developing fetus in a dose dependent manner. With very high repetitive doses there is a 6-10% chance of the fetus developing the fetal alcoholic syndrome manifested by prenatal and postnatal growth deficiency, specific craniofacial dysmorphic features, mental retardation, behavioral changes and a variety of major anomalies. With lower repetitive doses there is a risk of "alcoholic effects" mainly manifested by slight intellectual impairment, growth disturbances and behavioral changes. Binge drinking may impose some danger of slight intellectual deficiency. It is advised to offer maternal abstinence programs prior to pregnancy, but they may also be initiated during pregnancy with accompanying close medical care. The long term intellectual outcome of children born to ethanol dependent mothers is influenced to a large extent by the environment in which the exposed child is raised.