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The CHRNA5-A3 region on chromosome 15q24-25.1 is a risk factor both for nicotine dependence and for lung cancer.

ABSTRACT: Common variants in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24-25.1 were associated with lung cancer risk in three recently published independently conducted genome-wide association studies, with no consensus as to the relative impact of the variants on the propensity to smoke vs a direct carcinogenic effect. To further explore our hypothesis that these variants are indeed associated with both cancer causation and nicotine dependence, we performed a more detailed analysis of the association of these putative risk genotypes with smoking phenotype, as well as in lifetime never smokers, and in other smoking-related cancers. We demonstrate a statistically significant association of the variants with both nicotine dependence, as well as lung cancer phenotypes, including earlier age at lung cancer onset. The variants were associated with higher risks of lung cancer in lower smoking-exposed strata, and in individuals with a strong family history of lung or smoking-related cancers. In contrast, we found no evidence that the variants were associated with elevated risks in 547 lifetime never-smoking lung cancer case subjects, nor in other smoking-related cancers (bladder and renal). Thus, we conclude that the variants are implicated both in smoking behavior and more directly in lung cancer risk.

SUBMITTER: Spitz MR

PROVIDER: S-EPMC2720751 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature

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The CHRNA5-A3 region on chromosome 15q24-25.1 is a risk factor both for nicotine dependence and for lung cancer.

Spitz Margaret R MR Amos Christopher I CI Dong Qiong Q Lin Jie J Wu Xifeng X

Journal of the National Cancer Institute 20081028 21

Common variants in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24-25.1 were associated with lung cancer risk in three recently published independently conducted genome-wide association studies, with no consensus as to the relative impact of the variants on the propensity to smoke vs a direct carcinogenic effect. To further explore our hypothesis that these variants are indeed associated with both cancer causation and nicotine dependence, we performed a more detailed analys ...[more]

PMID: 18957677

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Project description:BackgroundThe CHRNA5/A3/B4 gene locus is associated with nicotine dependence and other smoking related disorders. While the non-synonymous CHRNA5 variant rs16969968 appears to be the main risk factor, linkage disequilibrium (LD) bins in the gene cluster carry frequent variants that regulate expression. Pairwise LD and haplotype analyses had identified at least three haplotype tagging SNPs including rs16969968 as main genetic risk factors. Searching for variants with evidence of regulatory functions, we have reported interactions between CHRNA5 and CHRNA3 enhancer variants (tagged by rs880395 and rs1948, respectively) and rs16969968, forming 3-SNP haplotypes and diplotypes that may more accurately reflect the cluster's combined effects on nicotine dependence (Barrie et al., Hum Mutat 38:112-9, 2017). Here we address further contributions by variants affecting CHRNB4, a possibly limiting component of nicotinic receptors.ResultsWe identify an LD bin (tagged by rs4887074) associated with expression of CHRNB4. Additive logistic regression models indicate that rs4887074 is associated with nicotine dependence and modulates the effect of rs16969968 in GWAS datasets (COGEND, UW-TTURC, SAGE). 4-SNP haplotype and diplotype analyses (rs880395-rs16969968-rs1948 -rs4887074) yield nicotine dependence risk values that further differentiate those obtained with the 3-SNP model. Moreover, both the main G allele of rs16969968 and the minor G allele of rs4887074 (associated with reduced expression of CHRNB4), residing predominantly on common haplotypes that are protective, represent significant allele-specific variance QTLs, indicating that they interact with each other.ConclusionsThese results indicate rs4887074 is associated with CHRNB4 expression, and along with two regulatory variants of CHRNA3 and CHRNA5, modulates the effect of rs16969968 on nicotine dependence risk. Assignable to individuals because of strong LD structures, 4-SNP haplotypes and diplotypes serve to assess the combined genetic influence of this multi-gene cluster on complex traits, accounting for complex LD relationships and tissue-specific genetic effects (CHRNA5/3) relevant to the traits analyzed. The 4-SNP haplotypes account at least in part for previous tagging SNPs, including the highly GWAS-significant rs6495308, located in a distinct pair-wise LD bin but included in protective 4-SNP haplotypes. Our approach refines and integrates the cluster's overall genetic influence, an important variable when integrating the genetics of multiple genomic loci.

Dataset Information

The CHRNA5-A3 region on chromosome 15q24-25.1 is a risk factor both for nicotine dependence and for lung cancer.

Publications

The CHRNA5-A3 region on chromosome 15q24-25.1 is a risk factor both for nicotine dependence and for lung cancer.

Similar Datasets

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