Meta-analyses of ALDH2 and ADH1B with alcohol dependence in Asians

Associations of ADH1B and ALDH2 genotypes and alcohol flushing with drinking history, withdrawal symptoms, and ICD-10 criteria in Japanese alcohol-dependent men

OBJECTIVES

Given the high prevalence of fast-metabolizing alcohol dehydrogenase-1B*2 (ADH1B*2 ) and inactive aldehyde dehydrogenase-2*2 (ALDH2*2 ) alleles in East Asians, we evaluated how the ADH1B / ALDH2 genotypes and alcohol flushing might affect the development of alcohol dependence (AD).

METHODS

We evaluated how the ADH1B / ALDH2 genotypes and self-reported alcohol flushing affected history of drinking events and withdrawal symptoms and ICD-10 criteria in 4116 Japanese AD men.

RESULTS

The ADH1B*1/*1 group and ALDH2*1/*1 group were 1-5 years younger than the ADH1B*2 (+) and ALDH2*1/*2 groups, respectively, for all of the ages at onset of habitual drinking, blackouts, daytime drinking, uncontrolled drinking, withdrawal symptoms, and first treatment for AD, and the current age. Blackouts were more common in the ADH1B*1/*1 group and ALDH2*1/*1 group. Daytime drinking, uncontrolled drinking, and withdrawal symptoms, such as hand tremor, sweating, convulsions, and delirium tremens/hallucinations were more common in the ADH1B*1/*1 group. The ADH1B*1/*1 was positively associated with the ICD-10 criteria for 'tolerance' and 'withdrawal symptoms'. The ADH1B*1/*1 group and ALDH2*1/*2 group had a larger ICD-10 score. Never flushing was reported by 91.7% and 35.2% of the ALDH2*1/*1 and ALDH2*1/*2 carriers, respectively. After a 1-2-year delay in the onset of habitual drinking in the former-/current-flushing group, no differences in the ages of the aforementioned drinking milestones were found according to the flushing status.

CONCLUSION

The ADH1B*1/*1 and ALDH2*1/*1 accelerated the development of drinking events and withdrawal symptoms in Japanese AD patients. ICD-10 score was larger in the ADH1B*1/*1 group and ALDH2*1/*2 group. The effects of alcohol flushing on drinking events were limited.

Long-term Risks of Cirrhosis and Hepatocellular Carcinoma Across Steatotic Liver Disease Subtypes

INTRODUCTION

The prospective study aimed to investigate the long-term associated risks of cirrhosis and hepatocellular carcinoma (HCC) across various subtypes of steatotic liver disease (SLD).

METHODS

We enrolled 332,175 adults who participated in a health screening program between 1997 and 2013. Participants were categorized into various subtypes, including metabolic dysfunction-associated SLD (MASLD), MASLD with excessive alcohol consumption (MetALD), and alcohol-related liver disease (ALD), based on ultrasonography findings, alcohol consumption patterns, and cardiometabolic risk factors. We used computerized data linkage with nationwide registries from 1997 to 2019 to ascertain the incidence of cirrhosis and HCC.

RESULTS

After a median follow-up of 16 years, 4,458 cases of cirrhosis and 1,392 cases of HCC occurred in the entire cohort, resulting in an incidence rate of 86.1 and 26.8 per 100,000 person-years, respectively. The ALD group exhibited the highest incidence rate for cirrhosis and HCC, followed by MetALD, MASLD, and non-SLD groups. The multivariate adjusted hazard ratios for HCC were 1.92 (95% confidence interval [CI] 1.51-2.44), 2.91 (95% CI 2.11-4.03), and 2.59 (95% CI 1.93-3.48) for MASLD, MetALD, and ALD, respectively, when compared with non-SLD without cardiometabolic risk factors. The pattern of the associated risk of cirrhosis was similar to that of HCC (all P value <0.001). The associated risk of cirrhosis for ALD increased to 4.74 (95% CI 4.08-5.52) when using non-SLD without cardiometabolic risk factors as a reference.

DISCUSSION

This study highlights elevated risks of cirrhosis and HCC across various subtypes of SLD compared with non-SLD, emphasizing the importance of behavioral modifications for early prevention.

Genetic architecture of alcohol consumption identified by a genotype-stratified GWAS and impact on esophageal cancer risk in Japanese people

An East Asian-specific variant on aldehyde dehydrogenase 2 (ALDH2 rs671, G>A) is the major genetic determinant of alcohol consumption. We performed an rs671 genotype-stratified genome-wide association study meta-analysis of alcohol consumption in 175,672 Japanese individuals to explore gene-gene interactions with rs671 behind drinking behavior. The analysis identified three genome-wide significant loci (GCKR, KLB, and ADH1B) in wild-type homozygotes and six (GCKR, ADH1B, ALDH1B1, ALDH1A1, ALDH2, and GOT2) in heterozygotes, with five showing genome-wide significant interaction with rs671. Genetic correlation analyses revealed ancestry-specific genetic architecture in heterozygotes. Of the discovered loci, four (GCKR, ADH1B, ALDH1A1, and ALDH2) were suggested to interact with rs671 in the risk of esophageal cancer, a representative alcohol-related disease. Our results identify the genotype-specific genetic architecture of alcohol consumption and reveal its potential impact on alcohol-related disease risk.

Association of serum individual and mixed aldehydes with depressive symptoms in the general population: A machine learning study

BACKGROUND

Humans have many opportunities to be exposed to aldehydes which have potential mechanisms for causing depression. We aimed to explore the relationships between serum individual and mixed aldehydes with depressive symptoms in general population.

METHODS

The data was extracted from the National Health and Nutrition Examination Survey 2013-2014. Depressive symptoms were assessed by Patient Health Questionnaire-9. Weighted binomial logistic regression and Bayesian kernel machine regression (BKMR) model were used to explore the association of six individual aldehyde and mixed aldehydes with depressive symptoms, respectively. Sex stratification analysis and sensitivity analysis were conducted.

RESULTS

A total of 701 participants were included. We found a positive association between the highest (Q4) versus lowest quartile (Q1) of butyraldehyde with depressive symptoms (OR: 2.86, 95 % CI: 1.22-6.68), and a negative association between the Q3 versus Q1 of benzaldehyde (0.21, 0.07-0.60) and isopentanaldehyde (0.28, 0.08-0.90) with depressive symptoms in multivariate-adjusted model. The mixed aldehydes were positively associated with depressive symptoms using BKMR model, and butyraldehyde and heptanaldehyde were the dominant aldehydes. Several aldehydes, such as butyraldehyde and benzaldehyde, interacted with each other in their effects on depressive symptoms. The results of gender stratification analysis showed that butyraldehyde was the major contributor to the total effect of aldehydes on depressive symptoms in males, while heptanaldehyde was the dominant aldehyde in females.

LIMITATIONS

Causality cannot be inferred in this cross-sectional study.

CONCLUSIONS

Our study indicated that mixed aldehydes can increase the risk of depressive symptoms, of which butyraldehyde and heptanaldehyde were the major contributing aldehydes.

Increased epithelial mTORC1 activity in chronic rhinosinusitis with nasal polyps

Background

The airway epithelium plays a central role in the pathogenesis of chronic respiratory diseases such as asthma and chronic rhinosinusitis with nasal polyps (CRSwNP), but the mechanisms by which airway epithelial cells (EpCs) maintain inflammation are poorly understood.

Objective

We hypothesized that transcriptomic assessment of sorted airway EpCs across the spectrum of differentiation would allow us to define mechanisms by which EpCs perpetuate airway inflammation.

Methods

Ethmoid sinus EpCs from adult patients with CRS were sorted into 3 subsets, bulk RNA sequenced, and analyzed for differentially expressed genes and pathways. Single cell RNA-seq (scRNA-seq) datasets from eosinophilic and non-eosinophilic CRSwNP and bulk RNA-seq of EpCs from mild/moderate and severe asthma were assessed. Immunofluorescent staining and ex vivo functional analysis of sinus EpCs were used to validate our findings.

Results

Analysis within and across purified EpC subsets revealed an enrichment in glycolytic programming in CRSwNP vs CRSsNP. Correlation analysis identified mammalian target of rapamycin complex 1 (mTORC1) as a potential regulator of the glycolytic program and identified EpC expression of cytokines and wound healing genes as potential sequelae. mTORC1 activity was upregulated in CRSwNP, and ex vivo inhibition demonstrated that mTOR is critical for EpC generation of CXCL8, IL-33, and CXCL2. Across patient samples, the degree of glycolytic activity was associated with T2 inflammation in CRSwNP, and with both T2 and non-T2 inflammation in severe asthma.

Conclusions

Together, these findings highlight a metabolic axis required to support epithelial generation of cytokines critical to both chronic T2 and non-T2 inflammation in CRSwNP and asthma.

ADH1B, ADH1B/C and CYP2E1 Gene Polymorphism and the Risk of Fetal Alcohol Spectrum Disorder

Increasing alcohol consumption by women of childbearing age contributes to more frequent cases of fetal alcohol spectrum disorder. The cause of the syndrome is fetal alcohol exposure, particularly what is referred to as high prenatal alcohol exposure. Low metabolic activity of fetal enzymes shifts the burden of ethanol removal to maternal metabolism. One of the factors influencing the pathogenesis of FASD is the genetic background. It can determine the rate of elimination of ethanol, thus increasing or decreasing the time of fetal exposure to ethanol and also decreasing its concentration. Genetic polymorphisms could potentially play a significant role in these processes. In the present study, we considered three polymorphisms of genes implicated in the synthesis of enzymes involved in ethanol metabolism, i.e., ADH1b (rs1229984), ADH1b/c (rs1789891), and CYP2E1 (rs3813867). The studied group consisted of 303 children and 251 mothers. Both mothers' and children's genotypes were considered in our analysis. There were no statistically significant differences between the respective groups of genotypes of the studied polymorphisms. However, the genetic background of FASD is still elusive.

Predictive risk markers in alcoholism

The medical disorders of alcoholism rank among the leading public health problems worldwide and the need for predictive and prognostic risk markers for assessing alcohol use disorders (AUD) has been widely acknowledged. Early-phase detection of problem drinking and associated tissue toxicity are important prerequisites for timely initiations of appropriate treatments and improving patient's committing to the objective of reducing drinking. Recent advances in clinical chemistry have provided novel approaches for a specific detection of heavy drinking through assays of unique ethanol metabolites, phosphatidylethanol (PEth) or ethyl glucuronide (EtG). Carbohydrate-deficient transferrin (CDT) measurements can be used to indicate severe alcohol problems. Hazardous drinking frequently manifests as heavy episodic drinking or in combinations with other unfavorable lifestyle factors, such as smoking, physical inactivity, poor diet or adiposity, which aggravate the metabolic consequences of alcohol intake in a supra-additive manner. Such interactions are also reflected in multiple disease outcomes and distinct abnormalities in biomarkers of liver function, inflammation and oxidative stress. Use of predictive biomarkers either alone or as part of specifically designed biological algorithms helps to predict both hepatic and extrahepatic morbidity in individuals with such risk factors. Novel approaches for assessing progression of fibrosis, a major determinant of prognosis in AUD, have also been made available. Predictive algorithms based on the combined use of biomarkers and clinical observations may prove to have a major impact on clinical decisions to detect AUD in early pre-symptomatic stages, stratify patients according to their substantially different disease risks and predict individual responses to treatment.

Hazardous drinking and alcohol use disorders

Alcohol is one of the most widely consumed psychoactive drugs globally. Hazardous drinking, defined by quantity and frequency of consumption, is associated with acute and chronic morbidity. Alcohol use disorders (AUDs) are psychiatric syndromes characterized by impaired control over drinking and other symptoms. Contemporary aetiological perspectives on AUDs apply a biopsychosocial framework that emphasizes the interplay of genetics, neurobiology, psychology, and an individual's social and societal context. There is strong evidence that AUDs are genetically influenced, but with a complex polygenic architecture. Likewise, there is robust evidence for environmental influences, such as adverse childhood exposures and maladaptive developmental trajectories. Well-established biological and psychological determinants of AUDs include neuroadaptive changes following persistent use, differences in brain structure and function, and motivational determinants including overvaluation of alcohol reinforcement, acute effects of environmental triggers and stress, elevations in multiple facets of impulsivity, and lack of alternative reinforcers. Social factors include bidirectional roles of social networks and sociocultural influences, such as public health control strategies and social determinants of health. An array of evidence-based approaches for reducing alcohol harms are available, including screening, pharmacotherapies, psychological interventions and policy strategies, but are substantially underused. Priorities for the field include translating advances in basic biobehavioural research into novel clinical applications and, in turn, promoting widespread implementation of evidence-based clinical approaches in practice and health-care systems.

Longitudinal effects and environmental moderation of ALDH2 and ADH1B gene variants on substance use from age 14 to 40

Alcohol use and dependence are strongly affected by variation in aldehyde dehydrogenase (ALDH2) and, to a lesser extent, alcohol dehydrogenase (ADH1B) genes. We use this genetic variation with an adoption design to test the causal role of alcohol use on other drug use, as well as the moderating role of adoptive parent, sibling, and peer alcohol use. Longitudinal models were run on 412 genotyped adopted individuals of East Asian ancestry with multiple assessments between ages 14 and 40. We found robust associations between alcohol frequency, quantity, and maximum drinks and ALDH2, but not ADH1B, status. The magnitude of the ALDH2 protective effect increased with age, particularly for maximum drinks, though estimates were smaller than previously reported in ancestrally similar individuals in East/North-East Asian countries. These results suggest that sociocultural factors in Minnesota may reduce the protective effects of ALDH2. We found that peer alcohol use, but not parent or sibling use, predicted adopted offspring's use, and that these environmental influences did not vary by ALDH2 status. Finally, we did not find strong evidence of associations between ALDH2 status and tobacco, marijuana, or illegal drug use, contrary to expectation if alcohol serves as a gateway to use of other drugs.

Alcohol-Induced Oxidative Stress and the Role of Antioxidants in Alcohol Use Disorder: A Systematic Review

Alcohol use disorder (AUD) is a highly prevalent, comorbid, and disabling disorder. The underlying mechanism of ethanol neurotoxicity and the involvement of oxidative stress is still not fully elucidated. However, ethanol metabolism has been associated with increased oxidative stress through alcohol dehydrogenase, the microsomal ethanol oxidation system, and catalase metabolic pathways. We searched the PubMed and genome-wide association studies (GWAS) catalog databases to review the literature systematically and summarized the findings focusing on AUD and alcohol abstinence in relation to oxidative stress. In addition, we reviewed the ClinicalTrials.gov resource of the US National Library of Medicine to identify all ongoing and completed clinical trials that include therapeutic interventions based on antioxidants. The retrieved clinical and preclinical studies show that oxidative stress impacts AUD through genetics, alcohol metabolism, inflammation, and neurodegeneration.

Alcohol-Associated Tissue Injury: Current Views on Pathophysiological Mechanisms

At-risk alcohol use is a major contributor to the global health care burden and leads to preventable deaths and diseases including alcohol addiction, alcoholic liver disease, cardiovascular disease, diabetes, traumatic injuries, gastrointestinal diseases, cancers, and fetal alcohol syndrome. Excessive and frequent alcohol consumption has increasingly been linked to alcohol-associated tissue injury and pathophysiology, which have significant adverse effects on multiple organ systems. Extensive research in animal and in vitro models has elucidated the salient mechanisms involved in alcohol-induced tissue and organ injury. In some cases, these pathophysiological mechanisms are shared across organ systems. The major alcohol- and alcohol metabolite-mediated mechanisms include oxidative stress, inflammation and immunometabolic dysregulation, gut leak and dysbiosis, cell death, extracellular matrix remodeling, endoplasmic reticulum stress, mitochondrial dysfunction, and epigenomic modifications. These mechanisms are complex and interrelated, and determining the interplay among them will make it possible to identify how they synergistically or additively interact to cause alcohol-mediated multiorgan injury. In this article, we review the current understanding of pathophysiological mechanisms involved in alcohol-induced tissue injury.

Exploring the Role of Alcohol Metabolizing Genotypes in a 12-Week Clinical Trial of Naltrexone for Alcohol Use Disorder

Background: The efficacy of naltrexone in the treatment of alcohol use disorder (AUD) has been associated with a set of variables not directly related with the expression of opioid receptors. All the variables have been found to be highly associated with AUD itself or more severe clinical levels of AUD. Objectives: Given the high association between alcohol metabolizing enzymes (AME) and the outcome of AUD, the present study aims to investigate the role of AME genotype variants in the treatment of AUD with naltrexone. Methods: We carried out a 12-week longitudinal clinical trial based on the treatment of AUD patients with naltrexone (N = 101), stratified by different alcohol metabolization genotypes. Genotyping was performed after the inclusion of the patients in the study, based on the individual presence of single nucleotide polymorphisms (SNPs) in the ADH (alcohol dehydrogenase)1B (ADH1B*2 and ADH1B*3), ADH1C (ADHC*1) and ALDH (aldehyde dehydrogenase) 2 (ALDH2*2) genes. The outcome of alcohol use has been monitored employing the timeline follow-back during the treatment. Results: The ADH1C*1 (Ile350Val, rs698) and ALDH2*2 (Glu504Lys, rs671) polymorphisms were associated with a better response to naltrexone treatment, whereas the ADH1B*3 (Arg370Cys, rs2066702) allelic variant showed a negative outcome. Conclusions: The present study explores a genomic setting for the treatment of AUD with naltrexone. According to our findings, the association between ADH1C*1 and ALDH2*2 variants and better outcomes suggests a successful treatment, whereas the ADH1B*3 mutated allele might lead to an unsuccessful treatment. Further studies should be performed to investigate the relationship between alcohol metabolizing genotypes, the family history of alcohol use disorders and the effect of naltrexone on the outcomes. Genotyping may be a valuable tool for precision-medicine and individualized approach, especially in the context of alcohol use disorders. The small number of subjects was the main limitation of the present study.

Cortical thickness is differently associated with ALDH2 rs671 polymorphism according to level of amyloid deposition

Accumulating evidence indicates that amyloid-beta (Aβ) deposition and biogenic aldehyde accumulation contribute to the pathogenesis of neurodegenerative diseases. Human aldehyde dehydrogenase 2 (ALDH2) metabolizes biogenic aldehydes produced in the brain to prevent damage. However, r671G>A, a single nucleotide polymorphism of ALDH2, causes aldehyde accumulation and decreased ALDH2 activity. We aimed to investigate whether Aβ deposition and rs671 polymorphism have an interaction effect on cortical thickness (CTh). We grouped 179 participants in the Biobank Innovations for chronic Cerebrovascular disease With ALZheimer's disease Study as follows: amyloid (–) [A(–)] and amyloid (+) [A(+)] groups based on the Aβ deposition degree; A-carrier (AC) and GG (GG) groups based on the presence/absence of the rs671 A allele; and their combinations, i.e., A(–)AC, A(–)GG, A(+)AC, and A(+)GG groups. A multiple regression analysis identified nine regions of interest. Compared with the A(–)GG group, the A(–)AC group showed thinner CTh in all regions. There were no significant differences between the A(+)AC and A(+)GG groups. We observed an interaction effect of amyloid deposition and rs671 polymorphism on CTh. The CTh in the A(–) group appeared to be strongly influenced by rs671 polymorphism, which could have contributed to cortical thinning and biogenic aldehyde accumulation in the AC group. Additionally, CTh in the A(+) group appeared to be strongly influenced by amyloid deposition.

Ethanol-Induced Cell Damage Can Result in the Development of Oral Tumors

Simple Summary

Alcohol consumption is linked to 26.4% of all lip and oral cavity cancer cases worldwide. Despite this clear causal relationship, the exact molecular mechanisms by which ethanol damages cells are still under investigation. It is well-established that the metabolism of ethanol plays an important role. Ethanol metabolism yields reactive metabolites that can directly damage the DNA. If the damage is repaired incorrectly, mutations can be fixed in the DNA sequence. Whenever mutations affect key regulatory genes, for instance cell cycle regulating genes, uncontrolled cell growth can be the consequence. Recently, global patterns of mutations have been identified. These so-called mutational signatures represent a fingerprint of the different mutational processes over time. Interestingly, there were ethanol-related signatures discovered that did not associate with ethanol metabolism. This finding highlights there might be other molecular effects of ethanol that are yet to be discovered.

Abstract

Alcohol consumption is an underestimated risk factor for the development of precancerous lesions in the oral cavity. Although alcohol is a well-accepted recreational drug, 26.4% of all lip and oral cavity cancers worldwide are related to heavy drinking. Molecular mechanisms underlying this carcinogenic effect of ethanol are still under investigation. An important damaging effect comes from the first metabolite of ethanol, being acetaldehyde. Concentrations of acetaldehyde detected in the oral cavity are relatively high due to the metabolization of ethanol by oral microbes. Acetaldehyde can directly damage the DNA by the formation of mutagenic DNA adducts and interstrand crosslinks. Additionally, ethanol is known to affect epigenetic methylation and acetylation patterns, which are important regulators of gene expression. Ethanol-induced hypomethylation can activate the expression of oncogenes which subsequently can result in malignant transformation. The recent identification of ethanol-related mutational signatures emphasizes the role of acetaldehyde in alcohol-associated carcinogenesis. However, not all signatures associated with alcohol intake also relate to acetaldehyde. This finding highlights that there might be other effects of ethanol yet to be discovered.

Combinations of alcohol-induced flushing with genetic polymorphisms of alcohol and aldehyde dehydrogenases and the risk of alcohol dependence in Japanese men and women

OBJECTIVE

The risk of alcohol dependence (AD) in Japanese men and women was evaluated according to combinations of alcohol flushing and aldehyde dehydrogenase-2 (ALDH2, rs671) and alcohol dehydrogenase-1B (ADH1B, rs1229984) genotypes, all of which are known to determine AD susceptibility in Asians. Previous studies have focused on men, since women account for a smaller proportion of AD subjects.

METHODS

Case control studies were conducted between 3721 male and 335 female AD Japanese and 610 male and 406 female controls who were asked about their current or former tendency to experience facial flushing after drinking a glass of beer and underwent ALDH2 and ADH1B genotyping. The time at which alcohol-induced facial flushing tendencies had disappeared in former-flushing AD subjects was also evaluated.

RESULTS

Current alcohol flushing, the inactive ALDH2*1/*2 genotype, and the fast-metabolizing ADH1B*2 allele were less frequently found in the AD groups. Although alcohol flushing was strongly influenced by the ALDH2 and ADH1B genotypes, multiple logistic model showed that never or former flushing and the genotype combinations were independent strong risk factors of AD in men and women. Never or former flushing (vs. current flushing) markedly increased the odds ratios of AD in carriers of each of the ALDH2 and ADH1B genotype combinations. The temporal profiles for drinking and flushing in former-flushing AD subjects revealed that the flushing response disappeared soon after or before the start of habitual drinking during young adulthood, regardless of the ALDH2 genotype.

CONCLUSION

Although alcohol flushing is influenced by the ALDH2 and ADH1B genotypes, constitutional or acquired flushing tolerance is an independent susceptibility trait for AD. The combination of the alcohol flushing status and the ALDH2 and ADH1B genotypes can provide a better new strategy for AD risk assessment than the alcohol flushing status alone or the genotypes alone in Asian men and women.

The Burden of Adverse Neonatal Outcome among Antenatal Substance Users in Ethiopia: A Systematic Review and Meta-Analysis

Background. Substances mainly khat, alcohol and cigarette are used during pregnancy in Ethiopia. However, to this date, there is no pooled evidence about the burden of adverse neonatal outcomes among the substance users during pregnancy in the country. Methods. Eligible primary studies were accessed from 4 international data bases (Google Scholar, Science Direct, Scopus, and PubMed). The required data were extracted from these studies and then exported to stata version 14 for analysis. Subgroup analyses were conducted for evidence of heterogeneity. Results. A total of 2298 neonates were included from 7 studies. Among these neonates, 530(23.06%) were those whose mothers used substance during pregnancy (exposed group) whereas 1768 neonates were those whose mothers didn’t use substance during pregnancy (controls group). The pooled prevalence of adverse neonatal outcome among the exposed mothers was 38.32% (95% CI: 29.48%, 47.16%; I² = 76.3%) whereas it was 16.29% (95% CI: 9.45%, 23.13%) among the controls. Adverse neonatal outcome was most burdensome among cigarette smokers 45.20% (95% CI: 37.68%, 52.73%; I² = .00%) when compared with khat chewers 34.00% (95% CI: 20.87%, 47.13%) and alcohol drinkers 38.47% (95% CI: 17.96%, 58.98%). Low birth weight 42.00% (95% CI: 18.01%, 65.99%; I² = 91.8%) was the most common adverse birth outcome. Conclusion. It was found that adverse neonatal outcomes were much more burdensome among antenatal substance users than the controls. Therefore, mothers should be enabled to quit using substance before pregnancy. Besides, strict comprehensive screening of every pregnant mother should be made at antenatal care clinics for early identification and management of antenatal substance use.

Alcohol in Psoriasis-From Bench to Bedside

Alcohol affects the symptoms, compliance and comorbidities as well as the safety and efficacy of treatments in psoriatic patients. In this review, we aim to summarize and link clinical observations with a molecular background, such as signaling pathways at the cellular level and genetic variations, and to provide an overview of how this knowledge could influence our treatment selection and patient management.

Primum Non Nocere: Should Gene Therapy Be Used to Prevent Potentially Fatal Disease but Enable Potentially Destructive Behavior?

Aldehyde dehydrogenase 2 (ALDH2) deficiency constitutes one of the most common hereditary enzyme deficiencies, affecting 35% to 40% of East Asians and 8% of the world population. It causes the well-known Asian Alcohol Flush Syndrome, characterized by facial flushing, palpitation, tachycardia, nausea, and other unpleasant feelings when alcohol is consumed. It is also associated with a marked increase in the risk of a variety of serious disorders, including esophageal cancer and osteoporosis. Our recent studies with murine models have demonstrated that a one-time administration of an adeno-associated virus (AAV) gene transfer vector expressing the human ALDH2 coding sequence (AAVrh.10hALDH2) will correct the deficiency state and prevent alcohol-induced abnormalities of the esophagus and bone. If successful in humans, such strategy would reduce the increased risk-associated disorders such as esophageal cancer and osteoporosis, but also prevent the Asian Alcohol Flush Syndrome. This treatment thus raises ethical concerns: although it would potentially prevent fatal disease, it could also allow affected individuals to drink alcohol without suffering the Asian Alcohol Flush Syndrome and, hence, potentially enable personal destructive behavior. Here we explore the ethical arguments against the development of a gene therapy for ALDH2 deficiency and we find them wanting. We contend that development of such treatments is ethically appropriate and should be part and parcel of the solutions offered against the condition.

The effect of substance use during pregnancy on neonatal outcomes in Ethiopia: A systematic review and meta-analysis

Background

Substance use during pregnancy mainly khat chewing (20%) and alcohol drinking (18.1%) are commonly practiced in Ethiopia. However, the effect of using these substances has not been studied nationally yet. Thus, this study was aimed to examine national evidence about the effect of substance use during pregnancy on birth outcome in the country, 2020.

Methods

Primary studies were accessed through Google scholar, HINARI, SCOPUS and PubMed databases. The methodological and evidence quality of the included studies were critically appraised by the modified Newcastle-Ottawa quality assessment tool scale adapted for observational studies. From eligible studies, two authors extracted author/year, study region, study design, sample size and reported effect of antenatal substance use on birth outcome on an excel spreadsheet. During critical appraisal and data extraction, disagreements between the two authors were resolved by the involvement of a third author. The extracted data were then exported to stata version 14. Effect sizes were pooled using the fixed-effects model due to homogenous primary studies (I² = 0.0%). Presence of publication bias was detected from asymmetry of funnel plot and statistically significant Egger's test (p = 0.000).

Results

In this systematic review and meta-analysis, a total of 5,343 mother-neonate pairs were included from 15 studies. Alcohol, khat, cigarette and narghile were used during pregnancy, and significant adverse birth outcomes attributable to these substances were reported. From the pooled effect of alcohol use, drinking mothers were twice (95%CI: AOR = 2.16; 1.16, 3.17) likely to have newborns with birth defect; 9 times (95% CI: AOR = 9.39; 2.84, 15.94) more prone to own low birth weight neonates; and 1.9 times more prone to deliver preterm neonates (95% CI: AOR = 1.93; 0.52, 3.33) than the nondrinkers. Khat users were 2.4 times (95%CI: AOR = 2.4; 1.11, 5.19) more likely to have congenitally defected neonates; and 3.1 times (95%CI: AOR = 3.19; 1.01, 5.37) more risked to possess low birth weight neonates. Furthermore, antenatal cigarette smokers (95% CI: AOR = 4.36 (1.75, 6.98)) and narghile users (95% CI: AOR = 20.1; 3.94, 103) were at 4 and 20 times more likelihood of having low birth weight neonates as compared to their counterparts.

Conclusion

Prematurity, low birth weight and congenital malformation were the investigated adverse effects of antenatal substance use in Ethiopia. Therefore, the existing public health efforts should be encouraged to help women stop using these substances completely before pregnancy. Moreover, increasing public awareness about the potential negative impacts of substance use during pregnancy on birth outcome would be of greatest importance for comprehensive prevention of the problem.

Behavioral predictors of individual differences in opioid addiction vulnerability as measured using i.v. self-administration in rats

BACKGROUND

Like other forms of psychopathology, vulnerability to opioid addiction is subject to wide individual differences. Animal behavioral models are valuable in advancing our understanding of mechanisms underlying vulnerability to the disorder's development and amenability to treatment.

METHODS

This review provides an overview of preclinical work on behavioral predictors of opioid addiction vulnerability as measured using the intravenous (i.v.) self-administration (SA) model in rats. We also highlight several new approaches to studying individual differences in opioid addiction vulnerability in preclinical models that could have greater sensitivity and lead to more clinically relevant findings.

RESULTS AND CONCLUSIONS

Evidence for the relationship between various behavioral traits and opioid SA in the preclinical literature is limited. With the possible exceptions of sensitivity to opioid agonist/withdrawal effects and stress reactivity, predictors of individual differences in SA of other drugs of abuse (e.g. sensation-seeking, impulsivity) do not predict vulnerability to opioid SA in rats. Refinement of SA measures and the use of multivariate designs and statistics could help identify predictors of opioid SA and lead to more clinically relevant studies on opioid addiction vulnerability.

ALDH1A1 Genetic Variations May Modulate Risk of Parkinson's Disease in Han Chinese Population

Background: Studies in animal models have suggested that aldehyde dehydrogenase 1 (encoded by ALDH1A1) protects against Parkinson’s disease (PD) by reducing toxic metabolites of dopamine. Herein we aimed to investigate whether ALDH1A1 was genetically associated with PD susceptibility in humans.

Methods: A Han Chinese population of 1,039 subjects was recruited to analyze six tag-single nucleotide polymorphisms (SNPs), followed by haplotype analyses and variants interaction analyses. Real-time PCR was used to analyze mRNA levels of ALDH1A1 in peripheral blood of 42 subjects.

Results: The tag-SNP rs7043217 of ALDH1A1 was significantly associated with PD susceptibility with the T serving as a risk allele (genotype frequency, P = 0.030; allele frequency, P = 0.013, OR = 1.258, 95% CI = 1.050–1.508). Multiple haplotypes were linked to abnormalities of PD risk, topped by a 4-SNP GGTA module in the order of rs4646547, rs1888202, rs7043217, and rs647880 (P = 9.610 × 10^–8, OR = 6.420, 95% CI = 2.944–13.998). Interaction analyses showed that a simultaneous presence of the CC genotype of rs7043217 and the TT genotype of ALDH2 variant rs4767944 conferred an elevated protection against PD (P = 4.68 × 10^–4, OR = 0.378, 95% CI = 0.219–0.652). The mRNA expression of ALDH1A1 showed a trend of reduction (P = 0.084) in PD patients compared to the controls.

Conclusion: Our results provide novel genetic insights into the role of ALDH1 in PD pathogenesis.

The influence of regression models on genome-wide association studies of alcohol dependence: a comparison of binary and quantitative analyses

INTRODUCTION

Genome-wide association studies (GWAS) of alcohol dependence syndrome (ADS) offer a platform to detect genetic risk loci. However, the majority of the ADS GWAS undertaken, to date, have utilized a case-control design and have failed to identify consistently replicable loci with the exception of protective variants within the alcohol metabolizing genes, notably ADH1B. The ADS phenotype shows considerable variability which means that the use of quantitative variables as a proxy for the severity of ADS has the potential to facilitate identification of risk loci by increasing statistical power. The current study aims to examine the influences of using binary and adjusted quantitative measures of ADS on GWAS outcomes and on calculated polygenic risk scores (PRS).

METHODS

A GWAS was performed in 1251 healthy controls with no history of excess alcohol use and 739 patients with ADS classified using binary DMS-IV criteria. Two additional GWAS were undertaken using a quantitative score based on DSM-IV criteria, which were applied assuming both normal and non-normal distributions of the phenotypic variables. PRS analyses were performed utilizing the data from the binary and the quantitative trait analyses.

RESULTS

No associations were identified at genome-wide significance in any of the individual GWAS; results were comparable in all three. The top associated single nucleotide polymorphism was located on the alcohol dehydrogenase gene cluster on chromosome 4, consistent with previous ADS GWAS. The quantitative trait analysis adjusted for the distribution of the criterion score and the associated PRS had the smallest standard errors and thus the greatest precision.

CONCLUSION

Further exploitation of the use of qualitative trait analysis in GWAS in ADS is warranted.

Alcohol Consumption, Cardiovascular-Related Conditions, and ALDH2*2 Ethnic Group Prevalence in Asian Americans

BACKGROUND

Little is known about the relationships between alcohol consumption and cardiovascular disease (CVD) and related chronic conditions in Asian Americans and how such risk relationships vary among their subgroups. We examine these relationships in Asian Americans and their moderation by ethnic prevalence of a variant the aldehyde dehydrogenase gene: ALDH2*2.

METHODS

Multiple logistic regression modeling was performed using a nationally representative sample of Asian-American adults aged 30 to 70 (n = 1,720) from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) Waves 2 (2004 to 2005) and 3 (2012 to 2013). Outcomes considered were diabetes, hypertension, high cholesterol, CVD, any of the 3 conditions (i.e., diabetes, high cholesterol, and CVD) documented to have a J-shaped relationship with drinking (CVDRC3), and any of the CVD-related conditions (ANYCVD). Demographic and socioeconomic characteristics, health insurance coverage, and other lifestyle risk factors (smoking and obesity/overweight) were adjusted. Analyses were stratified by gender.

RESULTS

Alcohol consumption level was positively associated only with hypertension in Asian males, with consuming 7 to 14 drinks per week associated with more than double the risk of lifetime abstinence. For females, alcohol consumption had a dose-response relationship with high cholesterol and CVDRC3. Membership in the higher ALDH2*2 ethnic group overall was associated with lower risk of CVD-related conditions. However, compared to abstainers in lower ALDH2*2 group, females in the higher ALDH2*2 group who consumed more than 7 drinks per week had a higher risk of diabetes, hypertension, CVDRC3, and ANYCVD.

CONCLUSIONS

Asian Americans may have increased risk of CVD-related conditions at relatively low alcohol consumption levels. Among Asian-American females, in particular, any amount of drinking may increase risk for high cholesterol or any of the CVD-related conditions previously documented to have a curvilinear relationship with drinking. These risks may be particularly elevated for those in ethnic groups with a high prevalence of ALDH2*2.

Impacts of interactions between ADH1B and ALDH2 genotypes on alcohol flushing, alcohol reeking on the day after drinking, and age distribution in Japanese alcohol-dependent men

OBJECTIVE

This study sought to evaluate the impacts of interactions between the alcohol dehydrogenase-1B (rs1229984) genotype and the aldehyde dehydrogenase-2 (rs671) genotype on alcohol flushing, alcohol reeking on the day after drinking, and the age distribution in alcohol-dependent patients.

METHODS

The study subjects were 4107 Japanese alcohol-dependent men who underwent alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 genotyping: 4051 patients were asked about their current or former tendency to experience facial flushing after drinking a glass of beer, and 969 patients were asked about whether they had ever been told that they reeked of alcohol more than 12 hours after they had stopped drinking.

RESULTS

Current, former, and never flushing were reported in 3.5, 14.9, and 81.5%, respectively, of the subject, and alcohol reeking after more than 12 hours in 36.1% of the subjects. The fast-metabolizing ADH1B*2(+) genotype (*1/*2 or *2/*2) and the inactive ALDH2*2(+) genotype (*1/*2 or *2/*2) affected the multivariate odds ratios for current or former flushing [odds ratio, 95% confidence interval = 2.27 (1.79-2.86) and 23.0 (18.6-28.5), respectively, vs. *2(-) genotype] and for alcohol reeking [0.39 (0.29-0.52) and 1.56 (1.09-2.25), respectively, vs. *2(-) genotype]. An age-dependent decrease in the ADH1B*2(-) and ALDH2*2(-) combination from 32.3% in the 30-39-year age group to 12.5% in the 70-79-year age group and an age-dependent increase in the ADH1B*2(+) and ALDH2*2(-) combination from 52.5% in the 30-39-year age group to 70.5% in the 70-79-year age group were observed (P < 0.0001 for trend). The frequencies of the ADH1B*2(-) and ALDH2*2(+) combination (4.7-6.2%) and the ADH1B*2(+) and ALDH2*2(+) combination (8.9-12.0%) did not change markedly with increasing age.

CONCLUSION

Interactions between the alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 genotypes modified alcohol flushing, alcohol reeking on the day after drinking, and the age distribution. These findings support the protective roles of the ADH1B*2(+) and ALDH2*2(+) genotypes against the development of alcohol dependence.

Alcohol consumption is associated with glaucoma severity regardless of ALDH2 polymorphism

The present study investigated the effect of aldehyde dehydrogenase2 (ALDH2) rs671 polymorphism and alcohol consumption on the severity of primary open-angle glaucoma (POAG). The questionnaire for alcohol consumption pattern and targeted genotyping for ALDH2 rs671 polymorphism was performed from 445 Korean POAG patients. Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thicknesses were measured and compared according to alcohol consumption and ALDH2 rs671 genotype. Heavy drinking group eyes had thinner RNFL thickness than did abstinence group eyes (65.0 ± 10.9 vs. 70.9 ± 11.5 µm, P = 0.023). Both mild (65.8 ± 9.6 µm) and heavy (63.8 ± 8.4 µm) drinking group eyes had significantly thinner macular GCIPL thickness than did abstinence group eyes (68.1 ± 8.2 µm, P = 0.003). However, ALDH2 rs671 polymorphism did not show any significant association with RNFL or GCIPL thickness. Alcohol consumption was significantly associated with GCIPL thinning (β = –0.446, P = 0.035) after adjustment for multiple confounding factors. As excessive alcohol consumption was significantly associated with thinner GCIPL thickness while ALDH2 polymorphism had no significant effect on RNFL or GCIPL thickness, glaucoma patients should avoid excessive alcohol consumption regardless of ALDH2 polymorphism.

Influence of Comorbid Psychiatric Disorders on the Risk of Development of Alcohol Dependence by Genetic Variations of ALDH2 and ADH1B

BACKGROUND

Inactive aldehyde dehydrogenase-2 (ALDH2) is a well-known deterrent to the development of alcohol use disorder (AUD), and however, some individuals with inactive ALDH2 do go on to develop AUD. These alcoholics are likely to have strong risk factors for the development of this disorder. Using a model of alcoholics with inactive ALDH2 (the AIA model), we investigated the unique characteristics of alcoholics with inactive ALDH2 in an attempt to identify the risk factors for AUD. In this study, we focused on comorbid psychiatric and personality disorders as potential risk factors for AUD.

METHODS

The subjects were 103 male alcoholics with inactive ALDH2 (AIAs), 87 age- and ADH1B genotype-matched alcoholics with active ALDH2 (AAAs) and 200 age-matched healthy men. The alcoholics were divided into 4 subgroups according to their ALDH2 and ADH1B genotypes (inactive ALDH2 vs. active ALDH2, usual ADH1B vs. superactive ADH1B). To assess the participants' comorbid psychiatric disorders, we conducted semi-structured interviews using the Japanese translation of SSAGA version 2. We compared the prevalence of comorbid psychiatric and personality disorders among groups with different combinations of the ALDH2 and ADH1B genotypes.

RESULTS

The prevalence of attention-deficit/hyperactivity disorder (ADHD) was significantly higher in the AIAs with usual ADH1B than in the other 3 subgroups of alcoholics. In contrast, the prevalence rates of agoraphobia and panic disorder were significantly lower in the AIAs with superactive ADH1B than in the other 3 subgroups of alcoholics.

CONCLUSIONS

This study suggested that (i) ADHD is a risk factor for AUD, consistent with previous reports; (ii) agoraphobia and panic disorder may have deterrent effects against the development of AUD in individuals with inactive ALDH2, probably attributable to the similarity between the symptoms of agoraphobia and panic disorder and the adverse reactions to consumption of alcohol in subjects with inactive ALDH2.

Genetic variants associated with alcohol dependence co-ordinate regulation of ADH genes in gastrointestinal and adipose tissues

GWAS studies have identified genetic variants associated with Alcohol Dependence (AD), but how they link to genes, their regulation and disease traits, remains largely unexplored. Here we integrated information on the 3D genome organization with expression quantitative loci (eQTLs) analysis, using CoDeS3D, to identify the functional impacts of single nucleotide polymorphisms associated with AD (p < 1 × 10-6). We report that 42% of the 285 significant tissue-specific regulatory interactions we identify were associated with four genes encoding Alcohol Dehydrogenase - ADH1A, ADH1B, ADH1C and ADH4. Identified eQTLs produced a co-ordinated regulatory action between ADH genes, especially between ADH1A and ADH1C within the subcutaneous adipose and gastrointestinal tissues. Five eQTLs were associated with regulatory motif alterations and tissue-specific histone marks consistent with these variants falling in enhancer and promoter regions. By contrast, few regulatory connections were identified in the stomach and liver. This suggests that changes in gene regulation associated with AD are linked to changes in tissues other than the primary sites of alcohol absorption and metabolism. Future work to functionally characterise the putative regulatory regions we have identified and their links to metabolic and regulatory changes in genes will improve our mechanistic understanding of AD disease development and progression.

Recent advances in genetic studies of alcohol use disorders

PURPOSE OF REVIEW

Alcohol use disorder (AUD) is a complex genetic disorder with very high heritability. This polygenic disorder not only results in increased morbidity and mortality, it is also a substantial social and economic burden on families and the nation. For past three decades, several genetic studies were conducted to identify genes and pathways associated with AUD. This review aims to summarize past efforts and recent advances in genetic association studies of AUD and related traits.

RECENT FINDINGS

Initial genetic association studies achieved a limted success and suffered from low power due to small sample sizes. AUD is a polygenic trait and data from several thousands individuals was required to identify the genetic factors of small effect sizes. The scenario changed recently with technological advances and significant reduction in cost of the genome wide association analyses (GWAS). This enabled researchers to generate genomic data on mega biobanks and cohorts with access to extensive clinical and non-clinical phenotypes. Public access to data from biobanks and collaborative efforts of researchers lead to identification of several novel loci associated with AUDs and related traits. Efforts are now underway to identify the causal variants under the GWAS loci to identify target genes and biological mechanisms underpining AUDs. Many GWAS variants occur in promoter or enhancer regions of the genes and are involved in regulation of gene expression of causal genes. This, large amounts of "omics" data from projects such as "ENCODE", RoadMap and GTEx is also helping researchers to integrate "multi-omics" data to interpret functional significance of GWAS variants.

SUMMARY

With current review, we aim to present the recent advances in genetic and molecular studies of AUDs. Recent successes in genetic studies of AUDs will definetely motivate researchers and lead to better therapeutic interventions for this complex disorder.

Aggressive-Depressive Trajectories in Childhood and Their Associations with Drinking Behaviors and Problems in Adolescence and Emerging Adulthood

Research indicates that externalizing and internalizing pathways emanated in childhood are connected to later drinking behaviors; however, no study has investigated the contemporaneous effects of the two pathways using a person-centered approach that categorizes individuals based on their various developmental patterns. This study examined the distinct patterns of concurrent development of aggression and depressive symptoms in childhood and their associations with later drinking behaviors using data from a 15-year Taiwanese cohort since age 8 (N = 2854, 49% females). Group-based multi-trajectory modeling identified four aggressive-depressive trajectory groups: Moderate, Aggressive, Depressive, and Comorbid, which manifested a sequential risk gradient in alcohol use. Comorbid group, characterized by persistently high levels of aggression and depressive symptoms, has the highest levels of alcohol use and drinking problems and the earliest onset of drinking. Aggressive and Depressive groups have higher levels of alcohol use and earlier onset of drinking than Moderate group. These findings imply the importance of monitoring aggression and depressive symptoms simultaneously and continually in childhood to prevent later drinking.

How Natural Genetic Variation Shapes Behavior

Nervous systems allow animals to acutely respond and behaviorally adapt to changes and recurring patterns in their environment at multiple timescales-from milliseconds to years. Behavior is further shaped at intergenerational timescales by genetic variation, drift, and selection. This sophistication and flexibility of behavior makes it challenging to measure behavior consistently in individual subjects and to compare it across individuals. In spite of these challenges, careful behavioral observations in nature and controlled measurements in the laboratory, combined with modern technologies and powerful genetic approaches, have led to important discoveries about the way genetic variation shapes behavior. A critical mass of genes whose variation is known to modulate behavior in nature is finally accumulating, allowing us to recognize emerging patterns. In this review, we first discuss genetic mapping approaches useful for studying behavior. We then survey how variation acts at different levels-in environmental sensation, in internal neuronal circuits, and outside the nervous system altogether-and then discuss the sources and types of molecular variation linked to behavior and the mechanisms that shape such variation. We end by discussing remaining questions in the field.

Meta-Analysis on Associations of Alcohol Metabolism Genes With Alcohol Use Disorder in East Asians

AIMS

The current meta-analysis tested independent and composite associations of three commonly studied alcohol metabolism alleles with alcohol use disorder (AUD) within East Asians as well as characterized potential moderating factors in these associations.

METHODS

For meta-analysis, 32 articles were selected that investigated ALDH2 (n = 17,755), ADH1B (n = 13,591) and ADH1C (n = 4,093) associations with AUD in East Asians.

RESULTS AND CONCLUSIONS

All three variants were associated with AUD across allelic and genotypic models: ALDH2, ORs = 0.25, P < 0.001; ADH1B, ORs = 0.22-0.49, P < 0.001; ADH1C, ORs = 0.26-0.46, P < 0.001. Composite analyses suggested genetic associations did not differ across ALDH2*2 and ADH1B*2, correcting for multiple comparisons. Moderation analyses suggested ADH1B was more strongly associated with AUD among samples with cases recruited from treatment than the community. Also, strength of ALDH2 and/or ADH1B associations varied with mean age and proportion of men in cases and controls. Findings support medium to large and unique associations of ALDH2, ADH1B, and ADH1C with AUD in East Asians. Results also identified novel methodological and sample characteristics that may modulate strength of these associations.

Genetic evidence for assortative mating on alcohol consumption in the UK Biobank

Alcohol use is correlated within spouse-pairs, but it is difficult to disentangle effects of alcohol consumption on mate-selection from social factors or the shared spousal environment. We hypothesised that genetic variants related to alcohol consumption may, via their effect on alcohol behaviour, influence mate selection. Here, we find strong evidence that an individual's self-reported alcohol consumption and their genotype at rs1229984, a missense variant in ADH1B, are associated with their partner's self-reported alcohol use. Applying Mendelian randomization, we estimate that a unit increase in an individual's weekly alcohol consumption increases partner's alcohol consumption by 0.26 units (95% C.I. 0.15, 0.38; P = 8.20 × 10^-6). Furthermore, we find evidence of spousal genotypic concordance for rs1229984, suggesting that spousal concordance for alcohol consumption existed prior to cohabitation. Although the SNP is strongly associated with ancestry, our results suggest some concordance independent of population stratification. Our findings suggest that alcohol behaviour directly influences mate selection.

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.

Performance of the Self-Report of the Effects of Alcohol Questionnaire Across Sexes and Generations

BACKGROUND

Low level of responses (low LRs) to alcohol established using the Self-Report of the Effects of Alcohol (SRE) questionnaire are genetically influenced phenotypes related to heavy drinking and alcohol problems. To date, most studies using SREs focused on scores for the number of drinks needed for effects across the first 5 times of drinking (SRE-5), and few evaluated scores that also included the prior 3 months and heaviest drinking periods (SRE-T). This paper evaluates characteristics of SRE-5 and SRE-T within and across generations.

METHODS

Data were extracted from 407 participants across 2 generations of 107 families in the San Diego Prospective Study (SDPS). Pearson's product-moment correlations for SRE-5 and SRE-T were determined across first-degree relatives both within and across generations and sexes, as well as correlations of each measure to maximum drinking quantities and alcohol problems.

RESULTS

Responding to 4 hypotheses, first the analyses demonstrated significant within-generation positive correlations for both SRE measures across brother-brother and sister-sister pairs as well as cross-generation correlations for fathers and sons, although correlations for mothers and daughters were not robust. Second, both SRE-5 and SRE-T correlated with maximum drinks and alcohol problems for both sexes and both generations. Third, within parental and offspring generations SRE-T correlated more robustly than SRE-5 to maximum drinks and alcohol problems. Fourth, across generations SRE values for sons were more closely related to drinking quantities and problems than for their fathers, but the mother-daughter SRE relationships to adverse alcohol characteristics were not different.

CONCLUSIONS

Both the SRE-5 and SRE-T offered useful information about propensities toward heavier drinking and alcohol problems in SDPS families. Correlations with adverse alcohol outcomes were greater for the more broad-based SRE-T, but both scores appeared to be genetically influenced and continue to operate in a robust manner in both generations of these families.

The Genetic Relationship Between Alcohol Consumption and Aspects of Problem Drinking in an Ascertained Sample

BACKGROUND

Genomewide association studies (GWAS) have begun to identify loci related to alcohol consumption, but little is known about whether this genetic propensity overlaps with specific indices of problem drinking in ascertained samples.

METHODS

In 6,731 European Americans who had been exposed to alcohol, we examined whether polygenic risk scores (PRS) from a GWAS of weekly alcohol consumption in the UK Biobank predicted variance in 6 alcohol-related phenotypes: alcohol use, maximum drinks within 24 hours (MAXD), total score on the Self-Rating of the Effects of Ethanol Questionnaire (SRE-T), DSM-IV alcohol dependence (DSM4AD), DSM-5 alcohol use disorder symptom counts (DSM5AUDSX), and reduction/cessation of problematic drinking. We also examined the extent to which an single nucleotide polymorphism (rs1229984) in ADH1B, which is strongly associated with both alcohol consumption and dependence, contributed to the polygenic association with these phenotypes and whether PRS interacted with sex, age, or family history of alcoholism to predict alcohol-related outcomes. We performed mixed-effect regression analyses, with family membership and recruitment site included as random effects, as well as survival modeling of age of onset of DSM4AD.

RESULTS

PRS for alcohol consumption significantly predicted variance in 5 of the 6 outcomes: alcohol use (Δmarginal R2  = 1.39%, Δ area under the curve [AUC] = 0.011), DSM4AD (Δmarginal R2  = 0.56%; ΔAUC = 0.003), DSM5AUDSX (Δmarginal R2  = 0.49%), MAXD (Δmarginal R2  = 0.31%), and SRE-T (Δmarginal R2  = 0.22%). PRS were also associated with onset of DSM4AD (hazard ratio = 1.11, p = 2.08e-5). The inclusion of rs1229984 attenuated the effects of the alcohol consumption PRS, particularly for DSM4AD and DSM5AUDSX, but the PRS continued to exert an independent effect for all 5 alcohol measures (Δmarginal R2 after controlling for ADH1B = 0.14 to 1.22%). Interactions between PRS and sex, age, or family history were nonsignificant.

CONCLUSIONS

Genetic propensity for typical alcohol consumption was associated with alcohol use and was also associated with 4 of the additional 5 outcomes, though the variance explained in this sample was modest. Future GWAS that focus on the multifaceted nature of AUD, which goes beyond consumption, might reveal additional information regarding the polygenic underpinnings of problem drinking.

Exome Chip Meta-analysis Fine Maps Causal Variants and Elucidates the Genetic Architecture of Rare Coding Variants in Smoking and Alcohol Use

BACKGROUND

Smoking and alcohol use have been associated with common genetic variants in multiple loci. Rare variants within these loci hold promise in the identification of biological mechanisms in substance use. Exome arrays and genotype imputation can now efficiently genotype rare nonsynonymous and loss of function variants. Such variants are expected to have deleterious functional consequences and to contribute to disease risk.

METHODS

We analyzed ∼250,000 rare variants from 16 independent studies genotyped with exome arrays and augmented this dataset with imputed data from the UK Biobank. Associations were tested for five phenotypes: cigarettes per day, pack-years, smoking initiation, age of smoking initiation, and alcoholic drinks per week. We conducted stratified heritability analyses, single-variant tests, and gene-based burden tests of nonsynonymous/loss-of-function coding variants. We performed a novel fine-mapping analysis to winnow the number of putative causal variants within associated loci.

RESULTS

Meta-analytic sample sizes ranged from 152,348 to 433,216, depending on the phenotype. Rare coding variation explained 1.1% to 2.2% of phenotypic variance, reflecting 11% to 18% of the total single nucleotide polymorphism heritability of these phenotypes. We identified 171 genome-wide associated loci across all phenotypes. Fine mapping identified putative causal variants with double base-pair resolution at 24 of these loci, and between three and 10 variants for 65 loci. Twenty loci contained rare coding variants in the 95% credible intervals.

CONCLUSIONS

Rare coding variation significantly contributes to the heritability of smoking and alcohol use. Fine-mapping genome-wide association study loci identifies specific variants contributing to the biological etiology of substance use behavior.

Prenatal alcohol exposure and facial morphology in a UK cohort

BACKGROUND

High levels of prenatal alcohol exposure are known to cause an array of adverse outcomes including fetal alcohol syndrome (FAS); however, the effects of low to moderate exposure are less-well characterized. Previous findings suggest that differences in normal-range facial morphology may be a marker for alcohol exposure and related adverse effects.

METHODS

In the Avon Longitudinal Study of Parents and Children, we tested for an association between maternal alcohol consumption and six FAS-related facial phenotypes in their offspring, using both self-report questionnaires and the maternal genotype at rs1229984 in ADH1B as measures of maternal alcohol consumption.

RESULTS

In both self-reported alcohol consumption (N = 4233) and rs1229984 genotype (N = 3139) analyses, we found no strong statistical evidence for an association between maternal alcohol consumption and facial phenotypes tested. The directions of effect estimates were compatible with the known effects of heavy alcohol exposure, but confidence intervals were largely centered around zero.

CONCLUSIONS

There is no strong evidence, in a sample representative of the general population, for an effect of prenatal alcohol exposure on normal-range variation in facial morphology.

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.

Transancestral GWAS of alcohol dependence reveals common genetic underpinnings with psychiatric disorders

Liability to alcohol dependence (AD) is heritable, but little is known about its complex polygenic architecture or its genetic relationship with other disorders. To discover loci associated with AD and characterize the relationship between AD and other psychiatric and behavioral outcomes, we carried out the largest genome-wide association study to date of DSM-IV-diagnosed AD. Genome-wide data on 14,904 individuals with AD and 37,944 controls from 28 case-control and family-based studies were meta-analyzed, stratified by genetic ancestry (European, n = 46,568; African, n = 6,280). Independent, genome-wide significant effects of different ADH1B variants were identified in European (rs1229984; P = 9.8 × 10-13) and African ancestries (rs2066702; P = 2.2 × 10-9). Significant genetic correlations were observed with 17 phenotypes, including schizophrenia, attention deficit-hyperactivity disorder, depression, and use of cigarettes and cannabis. The genetic underpinnings of AD only partially overlap with those for alcohol consumption, underscoring the genetic distinction between pathological and nonpathological drinking behaviors.

Conflict-related medial frontal theta as an endophenotype for alcohol use disorder

Diminished cognitive control in alcohol use disorder (AUD) is thought to be mediated by prefrontal cortex circuitry dysregulation. Research testing the relationship between AUD and specific cognitive control psychophysiological correlates, such as medial frontal (MF) theta-band EEG power, is scarce, and the etiology of this relationship is largely unknown. The current report tested relationship between pathological alcohol use through young adulthood and reduced conflict-related theta at age 29 in a large prospective population-based twin sample. Greater lifetime AUD symptomatology was associated with reduced MF theta power during response conflict, but not alpha-band visual attention processing. Follow-up analyses using cotwin control analysis and biometric modeling suggested that genetic influences, and not the consequences of sustained AUD symptomatology, explained the theta-AUD association. Results provide strong evidence that AUD is genetically related to diminished conflict-related MF theta, and advance MF theta as a promising electrophysiological correlate of AUD-related dysfunctional frontal circuitry.

Comparison of subjective response to alcohol in Caucasian and Hispanic/Latino samples

Individual differences in subjective response (SR) to alcohol (e.g., stimulation, sedation) are a significant predictor of negative alcohol outcomes. Previous studies have reported ethnic differences in SR (e.g., between some Asian populations and Caucasians), but very few studies have examined SR among Hispanic/Latino individuals. To address this gap in the literature, the present study utilized data from a large-scale, placebo-controlled alcohol administration study to examine differences in SR between Hispanic/Latino and Caucasian individuals. Social drinkers (N = 447) aged 21 to 25 years were randomized to receive either a dose of alcohol targeting a blood alcohol concentration (BAC) of .08 g% or placebo. Only non-Hispanic Caucasian participants (n = 234) and Hispanic/Latino participants (n = 87) were utilized in analyses. SR was assessed at baseline, on the ascending limb of the blood alcohol curve, at peak BAC, and on the descending limb. Repeated measures ANCOVA was utilized to examine interactions between beverage condition, ethnicity, and time predicting SR. The interaction between beverage condition, ethnicity, and time was significant only for low-arousal negative SR (negative sedative effects), such that Hispanic/Latino individuals experienced stronger sedative effects under alcohol (vs. placebo) compared with Caucasian individuals. Caucasians and Hispanic/Latinos showed a similar profile of response with respect to positive aspects of SR (e.g., stimulation). In summary, Hispanic/Latino individuals reported stronger negative SR to alcohol compared with Caucasian individuals, which may be protective against alcohol-related problems. However, future studies are needed to investigate why Hispanic/Latino males remain at relatively high risk for alcohol problems despite stronger negative SR relative to Caucasians. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The Role of Sex-Related Alcohol Expectancies in Alcohol-Involved Consensual and Nonconsensual Sex Among Women of Asian/Pacific Islander and Women of European Race/Ethnicity

Alcohol-involved sexual experiences, including incapacitated sexual assault and alcohol-involved sex, are major public health concerns among college women. Further, racial/ethnic diversity among college students is increasing, particularly with regard to increases in college students of Asian/Pacific Islander (API) race/ethnicity. Of relevance, evidence suggests differences in sexual assault rates across ethnicities and cultures; however, no known study to date has examined differences by ethnicity and first language in expectancies and experiences specifically surrounding alcohol and sex. The current study sought to examine differences in incapacitated sexual assault, alcohol-involved sex, and heavy episodic drinking, as well as differences in sex-related alcohol expectancies among native English-speaking college women of European (EU) race/ethnicity, native English-speaking women of API race/ethnicity, and non-native English-speaking women of API race/ethnicity (NNES-API). EU reported higher frequency of heavy episodic drinking, alcohol-involved sex, and incapacitated sexual assault compared to API and NNES-API. In addition, API reported more frequent alcohol-involved sex and incapacitated sexual assault compared to NNES-API, in part due to API's stronger endorsement of sexual disinhibition-related alcohol expectancies (indirect effects: β = -.04, p = .04, and β = -.07, p = .04, respectively). Findings highlight the important role of expectancies in acculturation and influence on actual alcohol-involved sex and sexual assault.

Component Model of Addiction Treatment: A Pragmatic Transdiagnostic Treatment Model of Behavioral and Substance Addictions

Behavioral addictions such as gambling, video games, sex, and shopping share many clinical features with substance use addictions including etiology, course, and neurobiology. Yet, the treatment of behavioral and substance use addictions tends to be separated. However, we argue that a more effective and efficient treatment approach is to conceptualize behavioral and substance use addictions as different expressions of a common underlying disorder and, in treatment, to address the underlying mechanisms common to both. To this end, the article presents a developing transdiagnostic treatment model of addictions that targets underlying similarities between behavioral and substance use addictions, called the component model of addiction treatment (CMAT). The CMAT is transdiagnostic in that it can be used in the treatment of both behavioral and substance use addictions. It is pragmatic in that it targets component vulnerabilities, which are enduring, yet malleable, individual psychological, cognitive, and neurobiological characteristics that are common to all addictive disorders and have been demonstrated to be modifiable. A working model of CMAT is presented, including proposed component vulnerabilities: lack of motivation, urgency, maladaptive expectancies, deficits in self-control, deficits in social support, and compulsivity, as well as their potential intervention possibilities. Future directions and potential implications of the CMAT are discussed.

Genetics of alcohol use disorder: a review

Alcohol use disorder (AUD) represents a significant and ongoing public health concern with 12-month prevalence estimates of ∼5.6%. Quantitative genetic studies suggest a heritability of approximately 50% for AUD, and as a result, significant efforts have been made to identify specific variation within the genome related to the etiology of AUD. Given the limited number of replicable findings that have emerged from genome-wide linkage and candidate gene association studies, more recent efforts have focused on the use of genome-wide association studies (GWAS). These studies have suggested that hundreds of variants across the genome, most of small effect (R² < 0.002), contribute to the genetic etiology of AUD. The present review describes the initial, though limited, successes of GWAS to identify loci related to risk for AUD as well as other etiologically relevant traits (e.g. alcohol consumption). In addition, 'Post-GWAS' approaches that rely on GWAS data to estimate the heritability and co-heritability of traits, test causal relations between traits, and aid in gene discovery are described. Together, the described research findings illustrate the importance of molecular genetic research on AUD as we seek to better understand the mechanisms through which genetic variation leads to increased risk for AUD.

Pharmacogenetic Effects of Naltrexone in Individuals of East Asian Descent: Human Laboratory Findings from a Randomized Trial

BACKGROUND

Genetic variation in the endogenous opioid system has been identified as 1 potential source of individual variability in naltrexone treatment outcomes. The majority of naltrexone pharmacogenetic studies have focused on a particular single nucleotide polymorphism (SNP) of the mu-opioid receptor gene (OPRM1; rs1799971; commonly known as the Asn40Asp SNP) in Caucasian samples with decidedly mixed results. The goal of this study was to test the pharmacogenetic effects of naltrexone on subjective response to alcohol and self-administration of alcohol in individuals of East Asian descent. We hypothesized that naltrexone, compared with placebo, would potentiate the aversive and sedative effects of alcohol and reduce alcohol self-administration to a greater extent in Asp40 carriers.

METHODS

Participants (N = 77; Asn40Asn, n = 29; Asn40Asp, n = 34, and Asp40Asp, n = 14) completed 2 double-blinded and counterbalanced experimental sessions: one after taking naltrexone (50 mg/d) for 5 days and one after taking matched placebo for 5 days. In each experimental session, participants received a priming dose of intravenous alcohol up to the breath alcohol concentration target of 0.06 g/dl which was immediately followed by an alcohol self-administration period (1 hour).

RESULTS

There were no pharmacogenetic effects observed for alcohol-induced stimulation, sedation, craving for alcohol, or alcohol self-administration in the laboratory. During the self-administration period, Asp40 carriers consumed fewer drinks and had a longer latency to first drink as compared to Asn40 homozygotes.

CONCLUSIONS

These findings in East Asians add to the mixed literature on naltrexone pharmacogenetics from predominantly Caucasian samples and highlight the complexity of these effects and their overall limited replicability. It is plausible that a consistent pharmacogenetic effect in tightly controlled preclinical and experimental medicine models "fades" in more complex and heterogeneous settings and samples.

Informing Prevention and Intervention Policy Using Genetic Studies of Resistance

The common paradigm for conceptualizing the influence of genetic and environmental factors on a particular disease relies on the concept of risk. Consequently, the bulk of etiologic, including genetic, work focuses on "risk" factors. These factors are aggregated at the high end of the distribution of liability to disease, the latent variable underlying the distribution of probability and severity of a disorder. However, liability has a symmetric but distinct aspect to risk, resistance to disorder. Resistance factors, aggregated at the low end of the liability distribution and supporting health and recovery, appear to be more promising for effective prevention and intervention. Herein, we discuss existing work on resistance factors, highlighting those with known genetic influences. We examine the utility of incorporating resistance genetics in prevention and intervention trials and compare the statistical power of a series of ascertainment schemes to develop a general framework for examining resistance outcomes in genetically informative designs. We find that an approach that samples individuals discordant on measured liability, a low-risk design, is the most feasible design and yields power equivalent to or higher than commonly used designs for detecting resistance genetic and environmental effects.

ALDH2*2 and peer drinking in East Asian college students

BACKGROUND

The ALDH2*2 allele (A-allele) at rs671 is more commonly carried by Asians and is associated with alcohol-related flushing, a strong adverse reaction to alcohol that is protective against drinking. Social factors, such as having friends who binge drink, also contribute to drinking in Asian youth.

OBJECTIVES

This study examined the interplay between ALDH2*2, peer drinking, and alcohol consumption in college students. We hypothesized that the relationship between ALDH2*2 and standard grams of ethanol per month would vary based on the level of peer drinking.

METHODS

Subjects (N = 318, 63.25% female) were East Asian college students in the United States who reported drinking alcohol. Data were from the freshman year of a university survey that included a saliva DNA sample. ALDH2*2 status was coded ALDH2*2(+) (A/G and A/A genotypes) and ALDH2*2(-) (G/G genotype). Peer drinking was students' perception of how many of their friends "got drunk".

RESULTS

Main effects of ALDH2*2(-) and having more friends who got drunk were associated with greater alcohol consumption. The ALDH2*2 × peer drunkenness interaction showed a stronger positive association with alcohol consumption for ALDH2*2(-) versus ALDH2*2(+) at increasing levels of peer drunkenness. Follow-up comparisons within each peer drunkenness level identified significantly higher alcohol consumption for ALDH2*2(-) compared to ALDH2*2(+) at the all friends got drunk level.

CONCLUSION

There was evidence of a stronger effect for ALDH2*2(-) compared to ALDH2*2(+) with greater alcohol use when students were more exposed to peer drinking. Findings contribute to a growing literature on the interrelationships between genetic influences and more permissive environments for alcohol consumption.

The Causal Role of Alcohol Use in Adolescent Externalizing and Internalizing Problems: A Mendelian Randomization Study

BACKGROUND

The co-occurrence of alcohol use and externalizing/internalizing problems threatens adolescents' mental health. Research on whether alcohol use and these problems are causal and the direction of the potential causal relationships is needed to understand the mechanisms of the co-occurrence.

METHODS

A Mendelian randomization analysis was conducted in which the aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphism was used as an instrumental variable for alcohol use phenotypes. In total, 1,608 Chinese adolescents (mean age 14.11 ± 1.83 years) were genotyped for the ALDH2 rs671 polymorphism. Three externalizing problems (aggression, delinquency, and attention problems) were measured with the Youth Self-Report inventory, and 2 internalizing problems (depression and anxiety) were measured with the self-reported Children's Depression Inventory and the Trait subscale of the State-Trait Anxiety Inventory.

RESULTS

Alcohol use was positively associated with all 3 externalizing and 2 internalizing problems, and the ALDH2 polymorphism had a significant effect on alcohol use. Aggression and attention problems were also significantly affected by the ALDH2 polymorphism, whereas no significant association was observed between the ALDH2 polymorphism and delinquency, anxiety, or depression.

CONCLUSIONS

The results suggest that alcohol use is a cause of adolescent aggression and attention problems but not adolescent delinquency, anxiety, or depression.

Age of Drinking Initiation as a Risk Factor for Alcohol Use Disorder Symptoms is Moderated by ALDH2*2 and Ethnicity

BACKGROUND

An early age of drinking initiation (ADI) has been associated with increased risk for alcohol use disorders (AUDs), but the consistency of this risk across diverse samples has not been well studied. The purpose of this study was to examine whether the pathway from ADI to AUD symptoms by early adulthood is moderated by ethnicity and possessing an alcohol-metabolizing gene ALDH2*2 variant allele.

METHODS

We used multigroup structural equation modeling, including 5 groups split by ethnicity and ALDH2*2, to examine the consistency of the path from ADI to AUD symptoms in 604 Chinese-, Korean-, and White-American college students. We further examined the effects of ALDH2*2, ethnicity, and their interaction in Asians to better understand their unique contributions to the moderation.

RESULTS

The association between ADI and AUD symptoms was moderated, with ADI negatively associated with AUD symptoms among Koreans without ALDH2*2 and Whites, but not among Koreans with ALDH2*2 or Chinese regardless of ALDH2*2. Both ALDH2*2 and ethnicity within Asians contributed unique variability in the effect.

CONCLUSIONS

Ethnicity and ALDH2*2 altered the relationship of ADI as a risk factor for AUD symptoms. Being Chinese and possessing an ALDH2*2 allele within Koreans both buffered against the risk for AUD symptoms associated with earlier ADI, indicating that this relationship can be attenuated by protective factors.