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An Exploratory Association Study of Alcohol Use Disorder and DNA Methylation.

ABSTRACT: BACKGROUND:Epigenetic factors, including DNA methylation, play an important role in the etiology of alcohol use disorders (AUDs). Noncandidate-based methylome-wide studies leveraging multiple tissue types are needed in order to identify a set of CpG targets that reliably differentiate AUD patients from controls and strongly correlate across brain tissue and more commonly collected tissue types (e.g., buccal cells). METHODS:Postmortem precuneus brain tissue samples were collected from 49 alcohol-dependent (AD) cases and 47 controls (sample I), and DNA was extracted from precuneus and putamen brain tissue and buccal cells in 24 postmortem subjects (sample II). Methylation levels were analyzed at over 450,000 CpG sites in both samples. CpGs that demonstrated significant methylation differences between cases and controls were advanced for further analysis with the goal of identifying CpGs that also demonstrated consistent methylation correlations across tissue type. RESULTS:In the primary analysis, 244 hypomethylated and 188 hypermethylated CpGs met a priori criteria for both significant methylation differences between cases and controls as well as significant correlation across brain and buccal cell tissue types, employing stringent Bonferroni p-value correction. Many of these CpGs were involved in gene networks related to lipid metabolism, immune response, inflammatory response/disease, and gastro-intestinal disease. CONCLUSIONS:More than 400 CpGs demonstrated differences in methylation between AD cases and controls and showed significant correlation across tissue types. Several genes and pathways (e.g., inflammation and immune functioning) that have been previously associated with AUD were identified in the current analyses.

SUBMITTER: Hagerty SL

PROVIDER: S-EPMC5108727 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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An Exploratory Association Study of Alcohol Use Disorder and DNA Methylation.

Hagerty Sarah L SL Bidwell L Cinnamon LC Harlaar Nicole N Hutchison Kent E KE

Alcoholism, clinical and experimental research 20160708 8

<h4>Background</h4>Epigenetic factors, including DNA methylation, play an important role in the etiology of alcohol use disorders (AUDs). Noncandidate-based methylome-wide studies leveraging multiple tissue types are needed in order to identify a set of CpG targets that reliably differentiate AUD patients from controls and strongly correlate across brain tissue and more commonly collected tissue types (e.g., buccal cells).<h4>Methods</h4>Postmortem precuneus brain tissue samples were collected f ...[more]

PMID: 27388583

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Project description:<p>The Australian twin-family study of alcohol use disorder (OZALC study) derives from telephone diagnostic interview studies of two general population volunteer cohorts of Australian twins (cohort 1, mostly born 1940-1964; cohort 2, born 1964-71) and the spouses of the former cohort - a total of over 11,000 families. Three coordinated studies, using a shared assessment protocol and with a shared goal of gene-discovery, were conducted - one funded by the National Institute on Drug Abuse, the others by the National Institute on Alcoholism and Alcohol Abuse - by investigators associated with the Midwest Alcoholism Research Center at Washington University in St. Louis, and investigators at Queensland Institute of Medical Research, Brisbane, Australia (led by Professor Nicholas Martin), using informative families identified from these cohorts. The first of these (NIDA Nicotine Addiction Genetics [NAG] project, PI Pamela Madden) identified index cases from the 3 cohorts with a history of heavy smoking (smoked 20 or more cigarettes daily, or 40 or more cigarettes on 1 or more occasions) and with additional available full siblings who were smokers, and interviewed and obtained blood samples from twins, and cooperative full siblings and parents, in order to identify families that would be informative for linkage analysis of a quantitative heaviness of smoking trait. The second identified additional families with an index case who either reported a history of alcohol dependence (DSM-IV), or scored above the 85th percentile on a quantitative measure of heaviness of alcohol use (alcohol factor score), derived from measures of frequency of heavy drinking, frequency of drinking to intoxication, and typical weekly consumption in standard drinks (all referenced to the respondent's heaviest drinking period) and of lifetime maximum 1-day alcohol consumption and maximum tolerance to alcohol (drinks before getting drunk or before feeling effects of alcohol). Interview and DNA were obtained from index cases and siblings, and DNA only from available parents. The goal of this second study (NIAAA OZ-ALCOHOL EDAC study, PI Andrew Heath) was to identify sibships including pairs who were either extreme concordant for the quantitative consumption measure (both scoring above the 85th percentile) or extreme discordant (one scoring above the 85th percentile and one scoring below the 30th percentile) that would be informative for linkage analysis. The third identified additional sibships solely on the basis of large sibship size, regardless of alcohol or tobacco use phenotypes (NIAAA OZ-BIGSIB study, PIs the late Richard Todd, Andrew Heath). From these coordinated studies a case-control series of alcohol dependent individuals and unaffected controls were constructed for a family-based Genomewide Association Study (OZALC-GWAS) of heaviness of alcohol use and alcohol dependence, funded by the National Institute of Alcoholism and Alcohol Abuse. These data are made available here for all investigators studying outcomes related to alcohol or tobacco use (including major depressive disorder).</p>

Project description:BackgroundPanic disorder (PD) is considered to be a multifactorial disorder emerging from interactions among multiple genetic and environmental factors. To date, although genetic studies reported several susceptibility genes with PD, few of them were replicated and the pathogenesis of PD remains to be clarified. Epigenetics is considered to play an important role in etiology of complex traits and diseases, and DNA methylation is one of the major forms of epigenetic modifications. In this study, we performed an epigenome-wide association study of PD using DNA methylation arrays so as to investigate the possibility that different levels of DNA methylation might be associated with PD.MethodsThe DNA methylation levels of CpG sites across the genome were examined with genomic DNA samples (PD, N = 48, control, N = 48) extracted from peripheral blood. Methylation arrays were used for the analysis. β values, which represent the levels of DNA methylation, were normalized via an appropriate pipeline. Then, β values were converted to M values via the logit transformation for epigenome-wide association study. The relationship between each DNA methylation site and PD was assessed by linear regression analysis with adjustments for the effects of leukocyte subsets.ResultsForty CpG sites showed significant association with PD at 5% FDR correction, though the differences of the DNA methylation levels were relatively small. Most of the significant CpG sites (37/40 CpG sites) were located in or around CpG islands. Many of the significant CpG sites (27/40 CpG sites) were located upstream of genes, and all such CpG sites with the exception of two were hypomethylated in PD subjects. A pathway analysis on the genes annotated to the significant CpG sites identified several pathways, including "positive regulation of lymphocyte activation."ConclusionsAlthough future studies with larger number of samples are necessary to confirm the small DNA methylation abnormalities associated with PD, there is a possibility that several CpG sites might be associated, together as a group, with PD.

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An Exploratory Association Study of Alcohol Use Disorder and DNA Methylation.

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An Exploratory Association Study of Alcohol Use Disorder and DNA Methylation.

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