Association Between Low-frequency Variations On Chromosome 5p15.33 And Risk Of Lung Cancer In Chinese Han Population

Objectives:Genome-wide association studies（GWAS）have identified chr5p15.33 as a susceptibility locus for lung cancer risk.However,the relationship between the low-frequency variants in this region and the risk of non-small cell lung cancer（NSCLC）,has not been systematically studied.In this study,we intended to explore the associations between low-frequency variants on 5p15.33 and the risk of NSCLC using a next-generation sequencing based approach.Methods:We have acquainted the variation spectrum of 400 NSCLC patients on chr5p15.33 by sequencing the targeted region before.Candidate variants were primarily selected by restricting the minor allele frequency（MAF 1-5%）,and then we compared their frequency between 400 NSCLC patients with 1,008 East Asians in the genome Aggregation Database（gnom AD）.The associations between candidate variants and NSCLC were discovered and validated in two case-control sets:discovery stage with 960 cases and 916controls,and replication stage with 1,596 cases and 1,614 controls in total.Results:Seven low-frequency variants were selected as candidate SNPs by genotype comparison,five of which were successfully genotyped,including:rs77518573,rs180675821,rs33963617,rs74368690,rs552616298.In the discovery stage,rs77518573（adjusted P=0.015）and rs33963617（adjusted P=0.045）were significantly associated with lung cancer susceptibility.We further validated the two promising associations in a replicated case-control study.The A allele of rs77518573（C>A）reduced the risk of lung cancer,the subjects carrying CA genotype reduced the lung cancer risk by 24%compared with individuals with CC genotype（OR=0.76,95%CI:0.64-0.91,P=0.003）.rs33963617（G>A）allele A also reduced risk of lung cancer,Heterozygous GA genotype significantly reduced the risk of lung cancer comparing with Wild-type homozygote GG genotype(OR=0.59,95%CI:0.48-0.75,P=6.00×10^-6).Subsequently,the combine analyses showed that two polymorphisms were significantly associated with risk of NSCLC in the dominant model,including rs33963617(OR=0.63,95%CI:0.53-0.76,P=3.80×10^-7)in TERT and rs77518573(OR=0.73,95%CI:0.63-0.84,P=2.00×10^-5)in upstream of CLPTM1L.When stratified by histologic subtype,rs33963617 was significantly associated with adenocarcinoma(OR=0.60,95%CI:0.49-0.74,P=1.00×10^-6)and squamous cell carcinoma（OR=0.68,95%CI:0.52-0.90,P=0.007）.However,the significant association was only found between rs77518573 and the risk of adenocarcinoma(OR=0.66,95%CI:0.56-0.79,P=2.00×10^-6).We also observed an obvious cumulative effect of the two significant variants.Individuals carrying one minor allele conferred significant reduced risk when compared with those carrying no minor allele at the two variants,and there was a gradual decrease in risk for NSCLC in subjects carrying more than one minor alleles.Specifically,compared with individuals harboring no minor allele,individuals carrying one,two or more minor alleles had an adjusted OR of0.75(95%CI:0.66-0.85,P=1.10×10^-5)and 0.34(95%CI:0.23-0.49,P=1.06×10^-8),respectively.Conclusions:We identified two NSCLC related variants on chromosome 5p15.33.Both TERT-rs33963617 and CLPTM1L-rs77518573 conferred reduced the risk of NSCLC in Chinese Han population.