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

Alcohol consumption and risk of psoriasis: Results from observational and genetic analyses in more than 100,000 individuals from the Danish general population

Background

Psoriasis is associated with high alcohol consumption, but the causality of this relationship is unclear.

Objective

We aimed to use a Mendelian randomization approach to investigate the causal effects of alcohol on incident psoriasis.

Methods

We included 102,655 adults from the prospective Copenhagen studies. All participants filled out a questionnaire on alcohol consumption, were physically examined, and had blood drawn for biochemical and genetic analyses. We created a genetic instrument based on the number of fast-metabolizing alleles in alcohol dehydrogenase 1B and alcohol dehydrogenase 1C, known to be associated with alcohol consumption, to test whether alcohol consumption was causally associated with psoriasis.

Results

Observationally, we found an increased risk of incident psoriasis among individuals with high alcohol consumption compared to those with low alcohol consumption with a hazard ratio of 1.30 (95% confidence interval 1.05-1.60) in the fully adjusted model. Using genetic data to predict alcohol consumption to avoid confounding and reverse causation, we found no association between number of fast-metabolizing alleles and risk of psoriasis.

Limitations

Alcohol consumption was self-reported and psoriasis was defined using the International Classification of Diseases 10th revision and 8th revision codes.

Conclusion

Alcohol consumption is observationally but not causally associated with incident psoriasis.

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.

Alcohol Intake and Risk of Ischemic and Haemorrhagic Stroke: Results from a Mendelian Randomisation Study

BACKGROUND AND PURPOSE

To test whether alcohol intake, both observational and estimated by genetic instruments, is associated with risk of ischemic and haemorrhagic stroke.

METHODS

We used data from the Copenhagen City Heart Study 1991 to 1994 and 2001 to 2003, and the Copenhagen General Population Study 2003 to 2012 (n=78,546). As measure of alcohol exposure, self-reported consumption and genetic variation in alcohol metabolizing genes (alcohol dehydrogenase ADH1B and ADH1C) as instrumental variables were used. Stroke diagnoses were obtained from a validated hospital register.

RESULTS

During follow-up 2,535 cases of ischemic and haemorrhagic stroke occurred. Low and moderate alcohol intake (1 to 20 drinks/week) was associated with reduced risk of stroke. The hazard ratios associated with drinking 1 to 6, 7 to 13, and 14 to 20 drinks/week were 0.84 (95% confidence interval [CI], 0.76 to 0.92), 0.83 (95% CI, 0.73 to 0.94), and 0.84 (95% CI, 0.73 to 0.97), respectively, compared with drinking <1 drink/day. ADH1B and ADH1C genotypes were not associated with risk of stroke. Further analysis to test the included measures revealed that increasing alcohol intake (per 1 drink/day) was positively associated with risk of alcoholic liver cirrhosis, but not associated with risk of stroke, and that increasing blood pressure (per systolic 10 mm Hg) was not associated with risk of alcoholic liver cirrhosis, but positively associated with risk of stroke.

CONCLUSIONS

Low and moderate self-reported alcohol intake was associated with reduced risk of stroke. The result was not supported by the result from the causal genetic analysis.

The BDNF Valine 68 to Methionine Polymorphism Increases Compulsive Alcohol Drinking in Mice That Is Reversed by Tropomyosin Receptor Kinase B Activation

BACKGROUND

The valine 66 to methionine (Met) polymorphism within the brain-derived neurotrophic factor (BDNF) sequence reduces activity-dependent BDNF release and is associated with psychiatric disorders in humans. Alcoholism is one of the most prevalent psychiatric diseases. Here, we tested the hypothesis that this polymorphism increases the severity of alcohol abuse disorders.

METHODS

We generated transgenic mice carrying the mouse homolog of the human Met66BDNF allele (Met68BDNF) and used alcohol-drinking paradigms in combination with viral-mediated gene delivery and pharmacology.

RESULTS

We found that Met68BDNF mice consumed excessive amounts of alcohol and continued to drink despite negative consequences, a hallmark of addiction. Importantly, compulsive alcohol intake was reversed by overexpression of the wild-type valine68BDNF allele in the ventromedial prefrontal cortex of the Met68BDNF mice or by systemic administration of the tropomyosin receptor kinase B agonist, LM22A-4.

CONCLUSIONS

Our findings suggest that carrying this BDNF allele increases the risk of developing uncontrolled and excessive alcohol drinking that can be reversed by directly activating the BDNF receptor, tropomyosin receptor kinase B. Importantly, this work identifies a potential therapeutic strategy for the treatment of compulsive alcohol drinking in humans carrying the Met66BDNF allele.

Influence of Dopaminergic System Genetic Variation and Lifestyle Factors on Excessive Alcohol Consumption

AIMS

To examine the role of genetic and environmental factors in the pathogenesis of alcohol dependence in a Spanish cohort of women and men.

METHODS

We analyzed the relationship between 56 genetic variants in 7 genes associated with the dopaminergic reward pathway and excessive alcohol consumption. The study sample (N = 1533, of which 746 were women) consisted of 653 heavy consumers and 880 very low consumers from the Spanish subcohort of the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Single nucleotide polymorphisms (SNPs) were genotyped using a customized array. Lifestyle variables were also examined to assess associations between genetic and environmental factors.

RESULTS

No statistically significant differences were found between cases and controls for the allele frequencies in five genes: TH, SLC18A2, DRD1, DRD3 and COMT. Conversely, some alleles of the 12 SNPs from the DRD2 locus and the 5 from the MAOA locus showed significant associations with excessive alcohol consumption. Namely, rs10891556 (DRD2) proved to be the only SNP positively correlated with excessive alcohol consumption in both sexes. DRD2 rs1800497 and rs877138 were significantly associated in men, whereas DRD2 rs17601612 and rs4936271 and MAOA rs5906898 were associated with excessive alcohol consumption in women. A correspondence analysis provided an overall lifestyle profile of excessive drinkers, who were predominantly men who smoked, had large intakes of meat, small intakes of fruit and vegetables, whose jobs did not require high education levels and who engaged in little physical activity.

CONCLUSIONS

It has shown the influence of dopaminergic pathway in the genetics of alcohol dependence with differences between men and women and providing a lifestyle profile of excessive drinkers.

Genetic susceptibility factors for alcohol-induced chronic pancreatitis

Chronic pancreatitis is a progressive inflammatory disease of the pancreas and frequently associated with immoderate alcohol consumption. Since only a small proportion of alcoholics eventually develop chronic pancreatitis genetic susceptibility factors have long been suspected to contribute to the pathogenesis of the disease. Smaller studies in ethnically defined populations have found that not only polymorphism in proteins involved in the metabolism of ethanol, such as Alcohol Dehydrogenase and Aldehyde Dehydrogenase, can confer a risk for developing chronic pancreatitis but also mutations that had previously been reported in association with idiopathic pancreatitis, such as SPINK1 mutations. In a much broader approach employing genome wide search strategies the NAPS study found that polymorphisms in the Trypsin locus (PRSS1 rs10273639), and the Claudin 2 locus (CLDN2-RIPPLY1-MORC4 locus rs7057398 and rs12688220) confer an increased risk of developing alcohol-induced pancreatitis. These results from North America have now been confirmed by a European consortium. In another genome wide approach polymorphisms in the genes encoding Fucosyltransferase 2 (FUT2) non-secretor status and blood group B were not only found in association with higher serum lipase levels in healthy volunteers but also to more than double the risk for developing alcohol-associated chronic pancreatitis. These novel genetic associations will allow to investigate the pathophysiological and biochemical basis of alcohol-induced chronic pancreatitis on a cellular level and in much more detail than previously possible.

Gene network analysis shows immune-signaling and ERK1/2 as novel genetic markers for multiple addiction phenotypes: alcohol, smoking and opioid addiction

Background

Addictions to alcohol and tobacco, known risk factors for cancer, are complex heritable disorders. Addictive behaviors have a bidirectional relationship with pain. We hypothesize that the associations between alcohol, smoking, and opioid addiction observed in cancer patients have a genetic basis. Therefore, using bioinformatics tools, we explored the underlying genetic basis and identified new candidate genes and common biological pathways for smoking, alcohol, and opioid addiction.

Results

Literature search showed 56 genes associated with alcohol, smoking and opioid addiction. Using Core Analysis function in Ingenuity Pathway Analysis software, we found that ERK1/2 was strongly interconnected across all three addiction networks. Genes involved in immune signaling pathways were shown across all three networks. Connect function from IPA My Pathway toolbox showed that DRD2 is the gene common to both the list of genetic variations associated with all three addiction phenotypes and the components of the brain neuronal signaling network involved in substance addiction. The top canonical pathways associated with the 56 genes were: 1) calcium signaling, 2) GPCR signaling, 3) cAMP-mediated signaling, 4) GABA receptor signaling, and 5) G-alpha i signaling.

Conlusions

Cancer patients are often prescribed opioids for cancer pain thus increasing their risk for opioid abuse and addiction. Our findings provide candidate genes and biological pathways underlying addiction phenotypes, which may be future targets for treatment of addiction. Further study of the variations of the candidate genes could allow physicians to make more informed decisions when treating cancer pain with opioid analgesics.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-015-0167-x) contains supplementary material, which is available to authorized users.

Predictors of subgroups based on maximum drinks per occasion over six years for 833 adolescents and young adults in COGA

OBJECTIVE

A person's pattern of heavier drinking often changes over time, especially during the early drinking years, and reflects complex relationships among a wide range of characteristics. Optimal understanding of the predictors of drinking during times of change might come from studies of trajectories of alcohol intake rather than cross-sectional evaluations.

METHOD

The patterns of maximum drinks per occasion were evaluated every 2 years between the average ages of 18 and 24 years for 833 subjects from the Collaborative Study on the Genetics of Alcoholism. Latent class growth analysis identified latent classes for the trajectories of maximum drinks, and then logistic regression analyses highlighted variables that best predicted class membership.

RESULTS

Four latent classes were found, including Class 1 (69%), with about 5 maximum drinks per occasion across time; Class 2 (15%), with about 9 drinks at baseline that increased to 18 across time; Class 3 (10%), who began with a maximum of 18 drinks per occasion but decreased to 9 over time; and Class 4 (6%), with a maximum of about 22 drinks across time. The most consistent predictors of higher drinking classes were female sex, a low baseline level of response to alcohol, externalizing characteristics, prior alcohol and tobacco use, and heavier drinking peers.

CONCLUSIONS

Four trajectory classes were observed and were best predicted by a combination of items that reflected demography, substance use, level of response and externalizing phenotypes, and baseline environment and attitudes.