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STUDY QUESTION Do genetic variants in known canonical pathways that have been widely suggested to affect spermatogenesis confer susceptibility to non-obstructive azoospermia (NOA)? SUMMARY ANSWER Rs1406714 in CHD2, rs2126986 in GNAO1 and rs7226979 in BCL2 were associated with NOA in Han Chinese men at a significant level after multiple testing corrections. WHAT IS KNOWN ALREADY Previous genome-wide association studies (GWASs) have identified three loci for NOA, whereas less attention has been given to those markers that did not exceed the genome-wide significance threshold. STUDY DESIGN, SIZE, DURATION We conducted a two-stage association study containing 1653 NOA cases and 2329 controls to investigate the susceptibility markers for NOA. PARTICIPANTS/MATERIALS, SETTING, METHODS Imputation and pathway-based approaches can be applied to identify additional causal makers with small effects on NOA. We performed a candidate pathway-based association study using imputed-genotyping data for 24 238 single nucleotide polymorphisms estimated from NOA GWAS. Remarkably, 40 markers were associated with NOA in both imputation analysis and NOA GWAS (Stage 1) after linkage disequilibrium analysis and selected for validation (Stage 2) in another population. MAIN RESULTS AND THE ROLE OF CHANCE Based on the literature, genes from 11 biological pathways known or hypothesized to be important in spermatogenesis were selected. Combined analysis using directly genotyped data for Stages 1 and 2 revealed that rs1406714 in CHD2 was associated with decreased risk of NOA [odds ratio (OR) = 0.78, 95% confidence interval (CI) = 0.68–0.89, Pmeta = 1.7E−04], whereas rs2126986 in GNAO1 and rs7226979 in BCL2 were both risk makers for NOA (rs2126986: OR = 1.28, 95% CI = 1.15–1.41, Pmeta = 2.3E−06; rs7226979: OR = 1.21, 95% CI = 1.11–1.33, Pmeta = 4.5E−05). LIMITATIONS, REASONS FOR CAUTION Our analysis of genes in the pathways studied was not exhaustive. WIDER IMPLICATIONS OF THE FINDINGS Our study opens new avenues for the identification of other novel causal markers that are related to NOA. It will also provide a new paradigm for understanding the etiology of male infertility and contribute to the development of targeted therapies. STUDY FUNDING/COMPETING INTEREST(S) This study was supported in part by National Basic Research Program of China (973 Program, 2011CB944304); National Science Fund for Outstanding Young Scholars (81322039); National Natural Science Foundation (31371524); Distinguished Young Scholars of Jiangsu Province (BK20130041); The Program for Postgraduates Research Innovation in University of Jiangsu Province (CXZZ12-0600). Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). There were no competing interests. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading cause of cancer-related deaths worldwide. By now, genome-wide association studies (GWAS) have identified numerous loci associated with the risk of developing lung cancer. However, these loci account for only a small fraction of the familial lung cancer risk. We hypothesized that epistasis may contribute to the missing heritability. To test this hypothesis, we systematically evaluated the association of epistasis of genetic variants with risk of lung cancer in Han Chinese cohorts. We conducted a pairwise genetic interaction analysis of 591370 variants, using BOolean Operation-based Screening and Testing (BOOST), in an ongoing GWAS of lung cancer that includes 2331 cases and 3077 controls. Pairs of epistatic loci with PBOOST ≤ 1.00×10−6 were further evaluated by a logistic regression model (LRM) with covariate adjustment. Four promising epistatic pairs identified at the screening stage (PLRM ≤ 2.86×10−13) were validated in two replication cohorts: the first from Beijing (1534 cases and 1489 controls) and the second from Shenyang and Guangzhou (2512 cases and 2449 controls). Using this combined analysis, we identified an interaction between rs2562796 and rs16832404 at 2p32.2 that was significantly associated with the risk of developing lung cancer (PLRM = 1.03×10−13 in total 13 392 subjects). This study is the first investigation of epistasis for lung cancer on a genome-wide scale in Han Chinese. It addresses part of the missing heritability in lung cancer risk and provides novel insight into the multifactorial etiology of lung cancer. [ABSTRACT FROM PUBLISHER]

Genetic variants at 5p15 have been associated with multiple cancers risk, suggesting pleiotropic effect on cancer. We hypothesized that genetic variants at 5p15 are important in the development of gastric cancer. To test this hypothesis, we evaluated the associations of genetic variants at 5p15 with gastric cancer based on our existing genome-wide association study (GWAS) data set of gastric cancer (1006 cases and 2273 controls), and replicated two promising loci in an independent case–control study with 1681 gastric cancer cases and 1705 controls in a Chinese population. We found that rs10052016 was consistently associated with gastric cancer risk in GWAS discovery stage (odds ratio [OR] = 0.69, 95% confidence interval [95% CI] = 0.55–0.87) and replication stage (OR = 0.80, 95% CI = 0.68–0.94). After combining these two studies, we found that the G allele of rs10052016 (at 132 kb upstream of TERT) was significantly associated with a decreased risk of gastric cancer (OR = 0.76, 95% CI = 0.67–0.87, P = 5.35 × 10–5). Moreover, the protective allele of rs10052016-G was also significantly associated with late onset of gastric cancer (P = 0.013). In summary, these findings indicate that genetic variants at 5p15 may contribute to gastric cancer susceptibility and may further advance our understanding of 5p15 locus in cancer development. [ABSTRACT FROM PUBLISHER]

Cell cycle regulation, apoptosis, oxidative stress and inflammation response play critical roles in the development of smoking-induced lung cancer. However, it is still not well known whether their genetic variants are associated with lung cancer susceptibility. In this study, we performed imputation-based association analyses to investigate the influence of common genetic variants in these pathways and their interactions with smoking on lung cancer susceptibility. We first selected 24 042 unvalidated genetic variants in 798 genes from the imputed dataset of the previous lung cancer genome-wide association study in 2331 cases and 3077 controls, and then conducted additional two-stage validations in 4133 cases and 4522 controls. We found a genome-wide significant (P < 5.0 × 10–8) association for rs2282987 in CDK6 at 7q21.2 [odds ratio (OR) = 1.18, combined Padd = 2.27 × 10–9] and a consistent association for rs2706748 in SH3RF1 at 4q32.3 (OR = 1.17, combined Padd = 5.10 × 10–6). Interaction analyses showed that rs2282987 and rs2706748 interacted with both smoking status (Pinteraction were 1.04 × 10–2 and 3.03 × 10–2, respectively) and smoking history (Pinteraction were 1.21 × 10–2 and 5.21 × 10–2, respectively) to contribute to lung cancer susceptibility in subjects aged 51–60 years. These results further underscore the contribution of genetic variants involved in pathways of cell cycle regulation and apoptosis to lung cancer susceptibility, and highlight gene–environment interactions in lung cancer etiology, especially in subjects aged 51–60 years. [ABSTRACT FROM AUTHOR]

STUDY QUESTION What are the genetic causes for the predisposition of certain Y chromosome haplogroups (Y-hgs) to spermatogenic impairment? SUMMARY ANSWER The AZFc(azoospermia factor c)/DAZ (deleted in azoospermia) duplications might underlie the susceptibility of Y-hg K* to spermatogenic impairment. WHAT IS KNOWN ALREADY The roles of Y chromosomal genetic background in spermatogenesis are controversial and vary among human populations. Individuals in predisposed Y-hgs may carry some genetic factors, which might be a potential genetic modifier for the Y-hg-specific susceptibility to spermatogenic impairment. STUDY DESIGN, SIZE, DURATION A total of 2444 individuals with azoospermia or oligozoospermia and 2456 healthy controls were recruited to this study from March 2004 and January 2011. PARTICIPANTS/MATERIALS, SETTING, METHODS We performed a two-stage association study to investigate the risk and/or protective Y-hgs for spermatogenic impairment. In addition, the genetic causes for the predisposition of certain Y-hg to spermatogenic impairment were investigated. Deletion typing and DAZ gene copy number quantification were performed for individuals in predisposed Y-hgs. MAIN RESULTS AND THE ROLE OF CHANCE Y-hgs K* and O3e* showed significantly different distribution between cases and controls consistently in two-stage studies. Combined analyses identified significant predisposition to non-obstructive azoospermia in Y-hg K* [odds ratio (OR) 8.58; 95% confidence interval (CI) 3.31–22.28; P = 1.40 × 10−5], but a protecting effect in Y-hg O3e* (OR 0.64; 95% CI 0.53–0.78; P = 4.20 × 10−5). Based on the dynamic nature of the Y chromosome, we hypothesized that Y-hgs K* and O3e* may be accompanied by modifying genetic factors for their predisposing or protecting effects in spermatogenesis. Accordingly, we quantified the multi-copy DAZ gene, which has variable copy numbers between individuals and plays an important role in spermatogenesis. In combined analysis, we found that the over-dosage of DAZ was significantly more frequent in Y-hg K* than in O3e* (OR 4.79; 95% CI 1.67–13.70; P = 6 × 10−3). LIMITATIONS, REASONS FOR CAUTION Owing to the inconsistency of genetic background, it remains to be determined whether the results derived from Han Chinese populations are applicable to other ethnic groups. WIDER IMPLICATIONS OF THE FINDINGS The findings of this study can advance the etiology of spermatogenic impairment, and also shed new light on Y chromosome evolution in human populations. Y-hg-specific genetic factors of modifying spermatogenic phenotypes deserve further investigation in larger and diverse populations. STUDY FUNDING/COMPETING INTEREST(S) Funding was provided by grants from National 973 Program (2009|CB941703, 2011CB944304 and 2012CB944600), National Natural Science Foundation of China (30930079, 81100461 and 31000552), Jiangsu Natural Science Foundation (BK2011774), Research Fund for the Doctoral Program of Higher Education of China (RFDP) (20113234120001), University Natural Science Research Project in Jiangsu Province (11KJB330001) and the Priority Academic Program for the Development of Jiangsu Higher Education Institutions (Public Health and Preventive Medicine). There were no competing interests. [ABSTRACT FROM PUBLISHER]

Germline mutations in genes that cause hereditary syndromes are highly predisposed to familial pancreatic cancer. However, genetic susceptibility to sporadic pancreatic cancer is largely uncovered. We conducted a two-stage association study on pancreatic cancer that included 981 cases and 1991 controls in the first stage followed by a second stage (2603 cases and 2877 controls). Using an approach based on candidate genes whose roles in pancreatic cancer have been well known, we identified two new susceptibility loci. rs11571836 located in the BRCA2 3′-untranslated region was significantly associated with lower expression of BRCA2 transcript and increased pancreatic cancer risk [odds ratio = 1.30, 95% confidence interval = 1.14–1.47, P = 7.64 × 10–5] in a recessive manner. rs12939944 located in the MAP2K4 intron was associated with decreased risk (odds ratio = 0.82, 95% confidence interval = 0.74–0.91, P = 0.0001) in a dominant manner. Our results demonstrate for the first time that common variants in BRCA2 and MAP2K4 are susceptibility to sporadic pancreatic cancer. [ABSTRACT FROM AUTHOR]

Two recent genome-wide association studies reported significant associations of genetic variants at 1q22, 10q23 and 20p13 with gastric cancer (GC) risk in Chinese populations. However, these findings have not been confirmed in other independent studies. Here, we performed an independent case–control study in a Chinese population by genotyping three loci (rs4072037A>G at 1q22, rs2274223A>G at 10q23 and rs13042395C>T at 20p13) in 1681 GC cases and 1858 controls. We found that rs4072037 at 1q22 and rs2274223 at 10q23 were significantly associated with risk of GC with per allele odds ratio (OR) of 0.72 [95% confidence interval (CI): 0.63–0.81; P = 2.98 × 10−7] and 1.42 (95% CI: 1.27–1.58; P = 9.68 × 10−10), respectively. The association was more prominent for rs2274223 in female (OR = 1.86, 95% CI: 1.49–2.32) and gastric cardia adenocarcinoma (GCA) (OR = 1.71, 95% CI: 1.49–1.95). Furthermore, we combined the two single-nucleotide polymorphisms to evaluate the joint effect and found that the GC risk significantly increased with the number of risk allele increasing with a trend P value of 6.66 × 10−16, and individuals with four risk alleles had a 3.28-fold (95% CI: 1.75–6.13) risk of GC compared with those having no risk alleles. However, no significant association was detected between rs13042395 at 20p13 and GC risk (OR = 1.04, 95% CI: 0.94–1.15; P = 0.452). In conclusion, our results indicate that genetic variants at 1q22 and 10q23 but not 20p13 may serve as candidate markers for GC susceptibility in the Chinese population. [ABSTRACT FROM AUTHOR]