Progress in the genetic studies of spermatogenesis abnormalities.

About 15% couples suffer from infertility, half of which are caused by male factors. Male infertility usually manifests as teratozoospermia, oligospermia and/or asthenospermia, of which the most severe form is azoospermia. In this review, we summarize the recent progress in the study of genetic factors involved in nonobstructive azoospermia and teratozoospermia, Recently, with the rapid development of high-throughput chips and sequencing technologies, many genetic factors of spermatogenesis have been discovered and analyzed. For the nonobstructive azoospermia, genome-wide association studies (GWAS) and high-throughput sequencing revealed many risk loci of nonobstructive azoospermia. For the teratozoospermia, the application of whole-exome sequencing (WES) revealed a series of disease-causing genes, greatly enriching our knowledge of teratozoospermia including multiple morphological abnormalities of the flagella (MMAF). The discovery of lots of disease genes helped the characterization of the pathological mechanisms of male infertility. Therefore, a comprehensive and in-depth understanding of genetic factors in spermatogenesis abnormalities will play important roles in the clinical diagnosis, treatment and genetic counseling of male infertility.

[Research advances on medical genetics in China in 2015].

Steady progress has been achieved in the medical genetics in China in 2015, as numerous original researches were published in the world's leading journals. Chinese scientists have made significant contributions to various fields of medical genetics, such as pathogenicity of rare diseases, predisposition of common diseases, somatic mutations of cancer, new technologies and methods, disease-related microRNAs (miRNAs), disease-related long non-coding RNAs (lncRNAs), disease-related competing endogenous RNAs (ceRNAs), disease-related RNA splicing and molecular evolution. In these fields, Chinese scientists have gradually formed the tendency, from common variants to rare variants, from single omic analyses to multipleomics integration analyses, from genetic discovery to functional confirmation, from basic research to clinical application. Meanwhile, the findings of Chinese scientists have been drawn great attentions of international peers. This review aims to provide an overall picture of the front in Chinese medical genetics, and highlights the important findings and their research strategy.

Genetic variants at 6p21.1 and 7p15.3 Identified by GWASs of multiple cancers and ovarian cancer risk: a case-control study in Han Chinese women.

A recent study summarized several published genome-wide association studies (GWASs) of cancer and reported two pleiotropic loci at 6p21.1 and 7p15.3 contributing to multiple cancers including lung cancer, noncardia gastric cancer (NCGC), and esophageal squamous-cell carcinoma (ESCC) in Han Chinese. However, it is not known whether such genetic variants have similar effects on the risk of gynecologic cancers, such as ovarian cancer. Hence, we explored associations between genetic variants in 6p21.1 and 7p15.3 and ovarian cancer risk in Han Chinese women. We performed an independent case-control study by genotyping the two loci (rs2494938 A > G at 6p21.1 and rs2285947 A > G at 7p15.3) in a total of 377 ovarian cancer cases and 1,034 cancer-free controls using TaqMan allelic discrimination assay. We found that rs2285947 at 7p15.3 was significantly associated with risk of ovarian cancer with per allele odds ratio (OR) of 1.33 [95% confidence interval (CI): 1.08-1.64, P=0.008]. However, no significant association was observed between rs2494938 and ovarian cancer risk. Our results showed that rs2285947 at 7p15.3 may also contribute to the development of ovarian cancer in Han Chinese women, further suggesting pleiotropy of 7p15.3 in multiple cancers.

[Association of polymorphisms of potassium voltage-gated channel, KQT-like subfamily, member 1 and type 2 diabetes in Jiangsu province, China].

OBJECTIVE: To study the association of polymorphisms in the potassium voltage-gated channel, KQT-like subfamily,member 1(KCNQ1) gene with type 2 diabetes in Chinese population from Jiangsu province. METHODS: Subjects consisting of 2925 cases and 3281 controls were enrolled from a community based cohort study of type 2 diabetes in Wuxi in 2007 and a community based cross-sectional survey on chronic non-communicable disease in Nantong in 2009. Epidemiological questionnaire survey and physical examinations were conducted and 10 h overnight fasting blood samples of 5 ml were drawn for all subjects.Genotypes were determined by TaqMan OpenArray Genotyping System and i-PLEX Sequenom MassARRAY platform. The relationship between KCNQ1 gene polymorphism and risk of type 2 diabetes after adjustment for age,sex and body mass index (BMI) was analyzed. RESULTS: The C allele of rs2237897, rs2237892 and rs2237895 at KCNQ1 increased the risk of type 2 diabetes with adjusted OR (95%CI) value being 1.41(1.30-1.54), 1.35(1.24-1.47), 1.22(1.12-1.33) respectively (all P value < 0.05) under the additive genetic model after adjusted by age,sex and BMI. Stratification analyses in additive genetic model showed that the C allele of rs2237897 increased the risk of type 2 diabetes in subgroups stratified by age ( ≤ 56 years and > 56 years), sex (females and males), BMI (< 24 kg/m(2) and ≥ 24 kg/m(2)) with OR (95%CI) value being 1.39(1.22-1.59), 1.43(1.28-1.60), 1.40(1.26-1.55), 1.44(1.26-1.66), 1.48(1.33-1.66), 1.34(1.17-1.53) respectively (all P value< 0.05). CONCLUSION: Polymorphisms of rs2237897, rs2237892 and rs2237895 in the KCNQ1 gene were associated with occurrence of type 2 diabetes among Jiangsu province population.

Epidemiologic differences in esophageal cancer between Asian and Western populations.

Esophageal cancer is a common cancer worldwide and has a poor prognosis. The incidence of esophageal squamous cell cancer has been decreasing, whereas the incidence of esophageal adenocarcinoma has been increasing rapidly, particularly in Western men. Squamous cell cancer continues to be the major type of esophageal cancer in Asia, and the main risk factors include tobacco smoking, alcohol consumption, hot beverage drinking, and poor nutrition. In contrast, esophageal adenocarcinoma predominately affects the whites, and the risk factors include smoking, obesity, and gastroesophageal reflux disease. In addition, Asians and Caucasians may have different susceptibilities to esophageal cancer due to different heritage backgrounds. However, comparison studies between these two populations are limited and need to be addressed in the near future. Ethnic differences should be taken into account in preventive and clinical practices.

Cancer risk and key components of metabolic syndrome: a population-based prospective cohort study in Chinese.

BACKGROUND: The key components of metabolic syndrome (MS) are waist circumference, blood pressure, fast blood glucose, high density lipoprotein cholesterol (HDL-c) and triglycerides (TG). These components have, separately and jointly, been associated with an increased risk of cardiovascular diseases. In this study, we aimed to explore the association between MS components and cancer risk in a population-based cohort in China. METHODS: We established a population-based cohort with 17 779 individuals aged 35 and above at baseline in 2004 and 2005 in Changzhou, Jiangsu Province, China. All participants were face-to-face interviewed to complete a questionnaire and were accepted physical examinations including blood tests for glucose and lipids and physical measurements for obesity and blood pressure. In 2009, a total of 16 284 subjects (6886 men and 9398 women, 91.6%) attended the flow-up interviews and the participants or their family members reported all the hospitalizations and diseases including cancer occurred during the follow-up period. Multivariate Cox regression was used to estimate the hazard ratios (HRs) of metabolic syndrome components and cancer incidence. RESULTS: There was a dose-response association between cancer risk and the number of MS components presented at baseline (P for trend = 0.012) and the HR (95% confidence interval (CI)) was 2.63 (1.27 - 5.45) for subjects carrying 3 or more metabolic syndrome components after adjustment for possible confounding factors. Specifically, the multivariate-adjusted HRs (95%CIs) for cancer risk in subjects with central obesity, high fasting glucose, low HDL-c were 1.94 (1.01 - 3.74), 2.04 (1.10 - 3.77) and 2.05 (1.09 - 3.88), respectively. CONCLUSIONS: In this population-based, prospective cohort study in China, we found MS components, e.g., central obesity, high fasting glucose, low HDL-c were risk factors for cancer development. Early intervention of MS components may be also beneficial to reduce cancer burden.

Lack of any relationship between chemotherapy toxicity in non-small cell lung cancer cases and polymorphisms in XRCC1 codon 399 or XPD codon 751.

PURPOSE: To examine the association between genetic polymorphisms (at XRCC1codon 399 or XPD codon 751) and chemotherapy related toxicities of non-small cell lung cancer. METHODS: One hundred and fifteen patients with histologically or cytologically confirmed stage IIIB and IV NSCLC recruited from Department of Chemotherapy of Jiangsu Cancer Hospital and Research Institute from 2005 to 2008, to evaluated the occurrence of chemotherapy related toxicities and the association with single nucleotide polymorphisms in XRCC1codon 399 or XPD codon 751. RESULTS: No significant association was observed between grade 0 or grade 1-4 overall toxicity and XRCC1 codon 399 (odds ratio=1.40, 95% confidence interval,0.73-2.66; adjusted odds ratio =1.43, 95% confidence interval,0.71-2.88), or XPD codon 751 genetic polymorphisms (odds ratio =0.87, 95% confidence interval,0.33-2.26; adjusted odds ratio=0.74, 95% confidence interval,0.26-2.13); similar results were found between hematologic, hepatic, gastrointestinal toxicities and XRCC1 399 or XPD 751 genetic polymorphisms. CONCLUSION: No statistically significant association was found between either XRCC1codon 399 or XPD codon 751 genetic polymorphisms and chemotherapy related toxicities.

Plasma Vitamin D Levels And Vitamin D Receptor Polymorphisms Are Associated with Survival of Non-small Cell Lung Cancer.

OBJECTIVE: Vitamin D and its receptor (VDR) involve in multiple cellular processes and play an important role in the initiation and progression of malignancy. Thus we hypothesized that plasma vitamin D levels and single nucleotide polymorphisms (SNPs) in VDR may be of prognostic significance in non-small cell lung cancer (NSCLC). METHODS: We examined plasma 25-hydroxyvitamin D [25(OH)D] levels in 87 patients diagnosed with NSCLC using enzyme-linked immunosorbent assay (ELISA) and genotyped seven potentially functional SNPs in VDR in 568 NSCLC patients on Illumina Golden Gate platform. RESULTS: Patients with higher plasma 25(OH)D levels had worse survival than patients with lower ones (P for trend = 0.048). The SNPs of rs1544410 and rs739837 were independently associated with NSCLC survival (adjusted HR = 1.61, 95% CIs = 1.06-2.45 for rs739837 AA vs AC/CC and adjusted HR = 1.51, 95% CIs = 1.06-2.16 for rs1544410 AG/AA vs GG). A joint effect was observed between rs1544410 and rs739837 and the risk of death elevated as the number of unfavourable genotypes patients carried increased (P for trend = 0.003). There were no significant associations between VDR polymorphisms and plasma 25(OH)D levels. CONCLUSION: Our findings indicate that plasma 25(OH)D levels and genetic variants of VDR may serve as prognostic markers for NSCLC in this Chinese population.

Potentially functional polymorphisms of the vascular endothelial growth factor gene and risk of gastric cancer.

Vascular endothelial growth factor (VEGF), the key mediator of angiogenesis, plays an important role in the development of different kind of tumors, including gastric cancer (GC). The aim of this study is to test the hypothesis that genetic variants of VEGF are associated with risk of GC. We genotyped four potentially functional polymorphisms (-2578C > A, -1498T > C, -634G > C, and +936C > T) of the VEGF gene in a population-based case-control study of 540 GC cases and 561 frequency-matched cancer-free controls in a high risk Chinese population. We found that none of the four polymorphisms or their haplotypes achieved significant difference in their distributions between GC cases and controls. Multiple logistic regression analyses revealed that GC risk was not significantly associated with the variant genotypes of the four VEGF polymorphisms as compared with their wild-type genotypes. In conclusion, our data did not support a significant association between VEGF SNPs and the risk of GC.

[Correlations of polymorphisms of TGFB1 and TGFBR2 genes to genetic susceptibility to gastric cancer].

BACKGROUND & OBJECTIVE: Transforming growth factor beta (TGFbeta) signaling pathway plays an important role in the genesis and progression of tumors through regulating cell proliferation and differentiation. The concentration of TGFbeta1 in plasma and the expression of TGFbeta receptor II (TGFbetaRII) are correlated to the development of certain tumors, including gastric cancer. This study was to explore the correlations of functional genetic variants in TGFB1 and TGFBR2 genes to the genetic susceptibility to gastric cancer. METHODS: A case-control study was conducted in Yixing City, a high incidence area of gastric cancer. Polymorphisms of TGFB1 C-509T, TGFB1 Leu10Pro, and TGFBR2 G-875A in 256 gastric cancer patients and 303 cancer-free controls, frequency-matched by age and sex, were determined by primer-introduced restriction analysis-polymerase chain reaction (PIRA-PCR). Crude and adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were measured by multivariate Logistic regression analysis to evaluate the correlations of the polymorphisms to the susceptibility to gastric cancer. RESULTS: The TGFB1 C-509T and TGFB1 Leu10Pro were in high linkage disequilibrium (D'=0.86). Compared with wild-type homogenous genetypes -509CC and 10 Leu/Leu, variant genetypes -509CT/TT, 10 Leu/Pro, and 10 Pro/Pro decreased the risk of gastric cancer by 49% and 34% (adjusted OR=0.51, 95% CI=0.36-0.74 for -509CT/TT; adjusted OR=0.66, 95% CI=0.45-0.98 for 10 Leu/Pro or 10 Pro/Pro). The risk of gastric cancer was decreased along with the number of variant sites in the TGFB1 C-509T and TGFBR2 G-875A (Chi(2)=15.70,P < 0.001). Stratified analysis showed that the protective effects of the genotypes were obvious in the subjects of no more than 60-year old (OR=0.42, 95% CI=0.23-0.79) and in non-drinkers (OR=0.45, 95% CI=0.27-0.74). CONCLUSION: Genetic variants of TGFB1 and TGFBR2 genes may contribute to the risk of developing gastric cancer in an eastern Chinese population in Yixing city.

Functional polymorphisms in the cyclooxygenase 2 (COX-2) gene and risk of breast cancer in a Chinese population.

Cyclooxygenase (COX), the rate-limiting enzyme in prostaglandins (PG) synthesis, exists in at least two isoforms, COX-1 and COX-2. COX-2 plays an important role in carcinogenesis, and overexpression may increase proliferation, inhibit apoptosis, and enhance the invasiveness of breast cancer cells. Polymorphisms in the regulatory regions of the COX-2 gene may influence function and/or expression and contribute to interindividual variability in susceptibility to cancer. In this study three variants (-1195G/A and -765G/C in the promoter and 8473C/T in 3'UTR) of COX-2 were examined for correlation with breast cancer risk. A case-control study of 615 histologically confirmed breast cancer patients and 643 cancer-free controls frequency-matched for age were selected. Logistic regression analyses revealed that no overall significant associations were detected in the single-locus analysis between three polymorphisms of COX-2 and the risk of breast cancer. However, a significantly increased risk of breast cancer was associated with the combined genotypes containing "more than 3 variant alleles"' (adjusted OR = 1.37, 95% CI 1.01-1.84) compared with the combined genotypes with "0-3 variant alleles." Haplotype analyses showed that haplotypes A-1195G-765T8473 and A-1195C-765T8473 were significantly associated with breast cancer risk (OR = 1.20, 95% CI 1.01-1.43 for A-1195G-765T8473; OR = 9.16, 95% CI 1.14-73.51 for A-1195C-765T8473) compared with the most common haplotype, G-1195G-765T8473. These findings indicate that these three variants in the regulatory regions of COX-2 may contribute to the etiology of breast cancer.

The association of polymorphisms of CDT1 and GMNN gene with the risk of breast cancer in Chinese women: a case-control analysis.

OBJECTIVE: To investigate the association of polymorphisms of CDT1 and GMNN gene, two important genes participating in DNA replication, with the risk of sporadic breast cancer. METHODS: Using polymerase chain reaction-restriction fragment length polymorphism (PCR - RFLP) and the primer-introduced restriction analysis (PIRA)-PCR assay to genotype the CDT1 838G/A and GMNN 387C/A polymorphisms in a case-control study of 427 breast cancer cases and 477 cancer-free controls in a Chinese population. RESULTS: No significant association of the CDT1 838G/A and GMNN 387C/A polymorphisms with the risk of breast cancer was found (adjusted OR:1.16, 95% CI:0.88-1.54 for CDT1 GA+AA genotypes and adjusted OR:0.90, 95% CI:0.67-1.21 for GMNN CA+AA genotypes). However, in the stratified analyses, a significant association of CDT1 GA+AA genotypes with breast cancer risk among subjects with family history of cancer was found (adjusted OR:2.21, 95% CI:1.20-4.09). CONCLUSION: These findings suggest that the CDT1 838G/A and GMNN 387C/A polymorphisms may not play a major role in the etiology of breast cancer, but CDT1 variant may have a potential role only in genetically susceptible women.