Dataset Information

Genome-wide association study on detailed profiles of smoking behavior and nicotine dependence in a twin sample.

ABSTRACT: Smoking is a major risk factor for several somatic diseases and is also emerging as a causal factor for neuropsychiatric disorders. Genome-wide association (GWA) and candidate gene studies for smoking behavior and nicotine dependence (ND) have disclosed too few predisposing variants to account for the high estimated heritability. Previous large-scale GWA studies have had very limited phenotypic definitions of relevance to smoking-related behavior, which has likely impeded the discovery of genetic effects. We performed GWA analyses on 1114 adult twins ascertained for ever smoking from the population-based Finnish Twin Cohort study. The availability of 17 smoking-related phenotypes allowed us to comprehensively portray the dimensions of smoking behavior, clustered into the domains of smoking initiation, amount smoked and ND. Our results highlight a locus on 16p12.3, with several single-nucleotide polymorphisms (SNPs) in the vicinity of CLEC19A showing association (P<1 × 10(-6)) with smoking quantity. Interestingly, CLEC19A is located close to a previously reported attention-deficit hyperactivity disorder (ADHD) linkage locus and an evident link between ADHD and smoking has been established. Intriguing preliminary association (P<1 × 10(-5)) was detected between DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th edition) ND diagnosis and several SNPs in ERBB4, coding for a Neuregulin receptor, on 2q33. The association between ERBB4 and DSM-IV ND diagnosis was replicated in an independent Australian sample. Recently, a significant increase in ErbB4 and Neuregulin 3 (Nrg3) expression was revealed following chronic nicotine exposure and withdrawal in mice and an association between NRG3 SNPs and smoking cessation success was detected in a clinical trial. ERBB4 has previously been associated with schizophrenia; further, it is located within an established schizophrenia linkage locus and within a linkage locus for a smoker phenotype identified in this sample. In conclusion, we disclose novel tentative evidence for the involvement of ERBB4 in ND, suggesting the involvement of the Neuregulin/ErbB signalling pathway in addictions and providing a plausible link between the high co-morbidity of schizophrenia and ND.

SUBMITTER: Loukola A

PROVIDER: S-EPMC3883996 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

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Genome-wide association study on detailed profiles of smoking behavior and nicotine dependence in a twin sample.

Loukola A A Wedenoja J J Keskitalo-Vuokko K K Broms U U Korhonen T T Ripatti S S Sarin A-P AP Pitkäniemi J J He L L Häppölä A A Heikkilä K K Chou Y-L YL Pergadia M L ML Heath A C AC Montgomery G W GW Martin N G NG Madden P A F PA Kaprio J J

Molecular psychiatry 20130611 5

Smoking is a major risk factor for several somatic diseases and is also emerging as a causal factor for neuropsychiatric disorders. Genome-wide association (GWA) and candidate gene studies for smoking behavior and nicotine dependence (ND) have disclosed too few predisposing variants to account for the high estimated heritability. Previous large-scale GWA studies have had very limited phenotypic definitions of relevance to smoking-related behavior, which has likely impeded the discovery of geneti ...[more]

PMID: 23752247

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Project description:Twin and family studies have provided overwhelming evidence for the genetic basis of individual differences in tobacco initiation (TI), regular smoking (RS) and nicotine dependence (ND). However, only a few genes have been reliably associated with ND. We used a finite mixture distribution model to examine the significance and effect size of the association of previously identified and replicated specific variants in the CHRNA5 and CHRNA3 receptor genes with ND, against the background of genetic and environmental risk factors for ND. We hypothesize that additional phenotypic information in relatives who have not been genotyped can be used to increase the power of detecting the genetic variant. The nicotine measures were assessed by personal interview in female, male and opposite sex twin pairs (N = 4,153) from the population-based Virginia Twin Registry. Three SNPs in the CHRNA5 and CHRNA3 receptor genes, previously shown to be significantly associated with ND in this sample, were replicated in the augmented analyses; they accounted for less than one percent of the genetic variance in liability to ND, which is estimated to be over 50% of the phenotypic variance. The significance of these effects was increased by adding twins with phenotype but without genotype data, but gains are limited and variable. The SNPs associated with ND did not show a significant association with either TI or RS and appear to be specific to the addictive stage of ND, characterized by current smoking and smoking a large amount of cigarettes per day. Furthermore, these SNPs did not appear to be associated with the remaining items comprising the FTND scale. This study confirmed a significant contribution of the CHRNA receptor on different forms of tobacco dependence. However, the genetic variant only accounted for little of the total genetic variance for liability to ND. Including phenotypic data on ungenotyped relatives can improve the statistical power to detect the effects of genetic variants when they contribute to individual differences in the phenotype.

Project description:Tobacco cigarette smoking, with nicotine (NIC) as the addictive component, is a large risk factor for human mortality. In animals, repeated NIC exposure leads to sensitization (SST) and enhances self-administration (SA) of NIC. However, the molecular basis of SST and SA and their genetic relevance to smoking behavior are poorly understood. Using F1 progeny of inbred Envigo rats (F344/BN), we carried out a transcriptional profiling of NIC SST and SA in ventral tegmental area (VTA), nucleus accumbens core (Nac) and shell (Nash). We observed male-specific NIC SST and a parental effect of NIC with SA only present in paternal F344 crosses. Gene differential expression (DE) analysis revealed sex and brain region-specific transcriptomic signatures of SST and SA, with genes downregulated in male VTA associated with both SST and SA, while genes upregulated in male Nac were associated with SA. DE genes associated with SST and SA are enriched for those related to synaptic processes, myelin sheath, and tobacco use disorder or chemdependency. Interestingly, we found that for SST the downregulated genes in the male VTA tended to be upregulated in female VTA, and the overlapping genes were strongly enriched for smoking genome-wide association study (GWAS) risk variants, which may thus explain male-specific SST. To gain mechanistic insight on the observed parental effect of SA, we analyzed the allelic imbalance of expression (AIE) in reciprocally crossed F1 rats that exhibited differential tendency of SA and found widespread region-specific AIE. For the SA-inclined rats, the genes showing AIE bias towards paternal F344 alleles in Nac were strongly enriched for genes upregulated in Nac DE—the gene set most relevant to NIC SA—and also for GWAS risk variants of smoking initiation. These findings show a prominent role for sex and region-specific gene expression and imprinting in NIC SST and SA, and suggest a mechanistic link between genes underlying these processes and human NIC addiction. This study provides a resource for understanding the biology underlying the genetic findings on human smoking phenotypes.

Dataset Information

Genome-wide association study on detailed profiles of smoking behavior and nicotine dependence in a twin sample.

Publications

Genome-wide association study on detailed profiles of smoking behavior and nicotine dependence in a twin sample.

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