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The importance of Vesicular Glutamate Transporter 2 (VGLUT2)-mediated neurotransmission has been highlighted in studies on addiction-related phenotypes. The single nucleotide polymorphism rs2290045 in VGLUT2 has been associated with alcohol dependence, but it is unknown whether or how this association is affected by environmental factors. The present study determined whether the association of alcohol-related problems with the rs2290045 in the VGLUT2 gene was modified by negative and positive environmental factors. Three samples were included: a clinical sample of 131 adolescents followed from age 17 to 22; a general population sample of 1794 young adults; and a general population sample of 1687 adolescents followed from age 14 to 17. DNA was extracted from saliva and the rs2290045 (T/C) was genotyped. Alcohol-related problems were assessed using the Alcohol Use Disorders Identification Test. Stressful life events (SLE) and parenting were assessed by questionnaires. Gene-environment interactions were investigated using a dual statistical approach. In all samples (effect sizes 0.6-6.2%), and consistent with the differential susceptibility framework, T carriers exposed to SLE reported more alcohol-related problems if they had experienced poor parenting, and lower alcohol-related problems if they had received supportive parenting. T carriers not exposed to SLE reported higher alcohol-related problems if they had received supportive parenting and lower alcohol-related problems if they had received poor parenting. Among CC carriers, alcohol-related problems did not vary as a function of negative and positive environmental factors. In conclusion, in three samples of youths, alcohol-related problems were associated with an interaction of VGLUT2 rs2290045, SLE, and parenting.

Background: Epigenetic mechanisms are candidate moderators of the effect of maltreatment on brain and behavior. Interactions between maltreatment and the monoamine oxidase A upstream variable number tandem repeat genotype (MAOA-uVNTR) are associated with alcohol-related problems. However, presently it is not known whether DNA methylation moderates this association. The study focused on 53 young adult males and aimed to determine whether MAOA methylation moderated the association of alcohol-related problems with the interaction of MAOA-uVNTR and maltreatment, and whether alcohol consumption moderated the association of MAOA methylation with the interaction of MAOA-uVNTR and maltreatment., Methods: MAOA-uVNTR genotypes with ≤ 3 and > 3 repeats were categorized as short (S) and long (L), respectively. Data on maltreatment were obtained retrospectively, using self-reported questionnaires. DNA methylation of 16 candidate CpGs within part of the MAOA first exon and intron was assessed and grouped based on principal component analyses. Alcohol-related problems were assessed using the Alcohol Use Disorders Identification Test (AUDIT). Alcohol consumption was measured using AUDIT-C. Moderation effects were assessed and probed using the moderated moderation model and Johnson-Neyman's method, respectively., Results: Carriers of the S allele, who experienced maltreatment and displayed lower Component 1 (mean of CpGs 13-16 in the first intron) MAOA methylation levels, reported higher AUDIT score in contrast to L-allele carriers. Carriers of the S allele, who reported higher AUDIT-C score and experienced maltreatment, displayed lower Component 3 (mean of CpGs 2-6 in the first exon) MAOA methylation levels than L-allele carriers., Conclusions: Intronic methylation moderated the association of alcohol-related problems with the interaction of MAOA-uVNTR and maltreatment. Alcohol consumption moderated the association of exonic methylation with the interaction of MAOA-uVNTR and maltreatment. These results suggest that epigenetic factors as well as genotype and maltreatment play a role in the development of alcohol misuse among young adult males., (Copyright © 2017 by the Research Society on Alcoholism.)

Genetic and environmental interactive influences on predisposition to develop alcohol use disorder (AUD) account for the high heterogeneity among AUD patients and make research on the risk and resiliency factors complicated. Several attempts have been made to identify the genetic basis of AUD; however, only few genetic polymorphisms have consistently been associated with AUD. Intermediate phenotypes are expected to be in-between proxies of basic neuronal biological processes and nosological symptoms of AUD. Personality is likely to be a top candidate intermediate phenotype for the dissection of the genetic underpinnings of different subtypes of AUD. To date, 38 studies have investigated personality traits, commonly assessed by the Cloninger's Tridimensional Personality Questionnaire (TPQ) or Temperament and Character Inventory (TCI), in relation to polymorphisms of candidate genes of neurotransmitter systems in alcohol-dependent patients. Particular attention has been given to the functional polymorphism of the serotonin transporter gene (5-HTTLPR), however, leading to contradictory results, whereas results with polymorphisms in other candidate monoaminergic genes (e.g., tryptophan hydroxylase, serotonin receptors, monoamine oxidases, dopamine receptors and transporter) are sparse. Only one genome-wide association study has been performed so far and identified the ABLIM1 gene of relevance for novelty seeking, harm avoidance and reward dependence in alcohol-dependent patients. Studies investigating genetic factors together with personality could help to define more homogenous subgroups of AUD patients and facilitate treatment strategies. This review also urges the scientific community to combine genetic data with psychobiological and environmental data to further dissect the link between personality and AUD.

The young brain is highly sensitive to environmental influences that can cause long-term changes in neuronal function, possibly through altered gene expression. The endogenous opioid system continues to mature after birth and because of its involvement in reward, an inadequate maturation of this system could lead to enhanced susceptibility for alcohol use disorder. Recent studies show that the classical reward areas nucleus accumbens and ventral tegmental area are less affected by early life stress whereas endogenous opioids in non-classical areas, e.g. dorsal striatum and amygdala, are highly responsive. The aim was to investigate the interaction between early life conditions and adult voluntary ethanol intake on opioid gene expression. Male Wistar rats were exposed to conventional rearing, 15, or 360min of daily maternal separation (MS) postnatal day 1-21, and randomly assigned to ethanol or water drinking postnatal week 10-16. Rats exposed to early life stress (MS360) had increased opioid receptor gene (Oprm1, Oprd1 and Oprk1) expression in the dorsal striatum. Ethanol drinking was associated with lower striatal Oprd1 and Oprk1 expression solely in rats exposed to early life stress. Furthermore, rats exposed to early life stress had high inherent Pomc expression in the amygdala but low expression after ethanol intake. Thus, adverse events early in life induced changes in opioid gene expression and also influenced the central molecular response to ethanol intake. These long-term consequences of early life stress can contribute to the enhanced risk for excessive ethanol intake and alcohol use disorder seen after exposure to childhood adversity., (Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.)

The aim of the present study was to investigate MAOA gene-environment (G*E) interactions in relation to adolescent alcohol consumption. In the county of Västmanland, Sweden, all 17-18-year-old students were asked to complete an anonymous questionnaire and provide a saliva sample during class hours. A total of 2263 students completed the questionnaire (77.4%) and a saliva sample was provided by 2131 participants. Failed MAOA u-variable number of tandem repeats (VNTR) genotype analyses and internal non-responses left 851 boys and 735 girls (total n=1586) to be investigated. Alcohol use disorder identification test was used to measure hazardous alcohol consumption. MAOA u-VNTR was used to measure biological risk in interaction with poor family relations and experience of sexual abuse. The model was also adjusted for non-independent socioeconomic variables, separated parents, type of housing and parental unemployment. Results showed that the MAOA u-VNTR, in interaction with psychosocial risk factors, such as the quality of family relations and sexual abuse, was related to high alcohol consumption among adolescents. Girls, carrying the long MAOA u-VNTR variant showed a higher risk of being high alcohol consumers, whereas among boys, the short allele was related to higher alcohol consumption. The present study supports the hypothesis that there is a relation between MAOA u-VNTR and alcohol consumption and that this relation is modulated by environmental factors. Furthermore, the present study also supports the hypothesis that there is a sex difference in the G*E interaction., (© 2010 The Authors, Addiction Biology © 2010 Society for the Study of Addiction.)

Background: Alcohol abuse is associated with sleep problems, which are often linked to circadian rhythm disturbances. Previous studies have separately examined the effects of mutations in the clock gene PER2 on alcohol consumption and sleep problems. Here we hypothesized that an allelic variation in the PER2 gene is associated with alcohol consumption in interaction with sleep problems among adolescents., Methods: The Survey of Adolescent Life and Health in Västmanland 2006, a Swedish county, including 1254 students 17-18 years old, was used as a population-representative sample of adolescents. We investigated the PER2 Single Nucleotide polymorphism (SNP) 10870 (A/G) in the cohort together with an assessment of alcohol consumption according to the AUDIT-C questionnaire, and sleep problems using a survey consisting of 18 items. Furthermore, we carried out an exploratory analysis on the PER2 Single Nucleotide Polymorphism 10870 polymorphism in a group of severely alcoholic females., Results: We found a significant association of the SNP 10870 in adolescent boys, where the genotype AA, in the presence of several and frequent sleep problems, was associated with increased alcohol consumption. Among adolescent girls, only sleep problems were related to alcohol consumption. A non-significant trend was observed among the severely alcoholic females, with the G allele being over-represented in the severely alcoholic females group in comparision to the control females., Conclusion: These results indicate that PER2 gene variation is associated with alcohol consumption in interaction with sleep problems among Swedish adolescent boys.

Susceptibility to alcoholism and antisocial behavior exhibits an evident link to monoaminergic neurotransmission. The serotonin system in particular, which is associated with regulation of mood and behavior, has an influence on personality characters that are firmly connected to risk of developing alcoholism and antisocial behavior, such as impulsiveness, and aggression. The transcription factor TFAP2b has repeatedly been shown to be involved in monoaminergic transmission, likely due to a regulatory effect on genes that are fundamental to this system, e.g. monoamine oxidase type A, and the serotonin transporter. Recent research has identified a functional polymorphism in the gene encoding TFAP2B that regulates its level of expression. In the present study we have compared a sample of female alcoholics (n=107), sentenced to institutional care for their severe addiction, contrasted against a control sample of adolescent females (n=875). The results showed that parental alcohol misuse was significantly more common among the alcoholic females, and also that parental alcohol misuse was associated with a reduction in age of alcohol debut. We also addressed the question of whether a functional TFAP2b polymorphism was associated with alcoholism. Results showed that the high-functioning allele was significantly more common among the female alcoholics, compared to the non-alcoholic controls. Furthermore, the results also indicated that psychosocial factors, in terms of parental alcohol misuse, depression or psychiatric disorder, had an influence on the association. It was observed that the genetic association was restricted to the subset of cases that had not experienced these negative psychosocial factors.