Study On The Relationship Between Protamine Gene Polymorphism And Male Infertility

Infertility has become a worldwide problem, men and women factors about half of each. More than 4000 genes involved in spermatogenesis, chromatin gathered enrichment, histone acetylation, and nucleosome formation, involving protamine (PRM), histone and transition nuclear protein (TNP) tightly controlled nuclear chromatin gathered, enrichment, assembly, a process that is closely related to spermatogenesis. Many domestic and international studies reported the correlation between some gene polymorphisms and male infertility, but by reason of sample size and different species distribution, the result is incongruent. To investigate the association of six single gene polymorphisms [PRM1 (rs35576928, rs737008 and rs2301365) and PRM2 (rs2070923 and rs1646022) and TNP1 (rs62180545)] and Chinese Han male infertility, we designed the experiment research, which provided experimental basis to predict the risk of male infertility.At the same time, we retrieved published studies of PRM gene polymorphisms and male infertility, analyzed and summarized the data included in some studied by using meta-analysis, further verified the association of PRM gene polymorphisms and male infertility.We used the cases-comparison research method, collected 636 infertile men as case group in Nanjing general hospital of Nanjing military region (including 544 patients with azoospermia and severe oligospermia and 92 patients with less or weak sperm), collected 442 fertile men as control group, using MassARRAY iPLEX GOLD technology to analyze six SNPs’ alleles and genotypes distribution [rs35576928 (G/T), rs737008 (G/A), rs2301365 (C/A), rs2070923 (C/A), rs1646022 (C/G) and rs62180545 (A/G)] and male infertility, using the chi-square and odds ratio (OR).Meta-analysis using statistical software Stata 11.0, which includes the process of strategy of retrieval formulation, collection and arrangement of litratures as well as extraction of data. We statistically calculated the pooled OR values and 95% confidence interval (95% CI) to analyze heterogeneity and sensitivity and drew the funnel plot to evaluate publication bias. We obtained the evidence-based medical result for correlation between the PRM gene polymorphism and male infertility.The case-control study results indicated that no statistical difference in average age, abstinence day was found. Besides, no statistical difference was found in semen volume, hormone levels [testosterone (T), luteinizing hormone (LH) and estrogen (E2)], though the semen pH, PR value, follicle-stimulating hormone (FSH) level in case group were found statistically different from the control group (P<0.05). Six gene polymorphisms in control group all conformed to the Hardy-Weinberg inheritance balance law, suggesting that prompt reference samples on behalf of group. Logistic regression analysis showed that six SNPs for PRM1, PRM2 and TNP1 were found not obviously associated with male infertility. Haplotype analysis showed that all haploid combination were obviously correlated with male infertility, among which either one (GCTCC, TCGGA and TCGGC) were risk factor for male infertility contrasted with protective factors (GCTGC, TCGCA and TCGCC). Linkage disequilibrium analysis showed that rs737008 was 99% hereditarily linked with rs2070923 (D’=0.996, r2=0.970),97% for rs2301365 and rs2070923 (D’=0.979, r2 = 0.678).98% for rs737008 and rs2301365 (D’= 0.984, r2=0.701). No obvious linkage effect was found lying within the other two combinations. Gene interaction analysis also indicated that either rs737008 or rs2301365 in PRMl gene displayed intereracted with rs1646022 in PRM2. In addition, when the male genotype displayed CG at rs 1646022 along with GT atrs737008, the risk for male infertility was 1.58 fold above normal men, while other genotype combinations lent protective effects.Meta analysis results:our study included 7350 male infertility patients and 6167 normal controls, the data of which were derived from 13 case-control studies. The results showed that rs2301365 was risk factor for male infertility, both rs737008 and rs 1646022 in Asian and population-based (PB) subgroup exhibited statistical difference, bearing protective effect againstmale infertility. Other sites were found no correlation with male infertility. Statistical results show that the no model was present withthe heterogeneity, as was significant statistical difference in sensitivity analysis. Funnel plot, Begge’s and Egger’s testing results suggested the result of our study was reliable and absent of publication bias.Experimental research shows that six SNPs for PRM1, PRM2 and TNP1 were found not obviously associated with male infertility. Subgroup analysis also did not find any correlation with male infertility. Three haploid combinations (GCTGC, TCGCA and TCGCC) of men suffering from infertility had protective effect against male infertility while the other three-bearing cohort (GCTCC, TCGGA and TCGGC) suffered male infertility 2.03～5.73 fold abovenormal group. Either rs737008 or rs2301365 in PRM1 gene displayed intereracted with rs 1646022 in PRM2. When the male genotype displayed CGGT at rs 1646022 along with GT at rs737008, the risk for male infertility was 1.58 fold above normal men in suffering male infertility, and some while other genotype combinations does lent protective factorseffects. Five SNPs total in PRM1/2 was not interacted with rs62180545 in TNP1. Meta-analysis showed that polymorphism at rs2301365 within 5’-UTR region of PRM1 in all models was a risk factor for male infertility. Polymorphisms at rs 1646022 and rs737008 are in Asian and the PB group was a protective factor against male infertility in major models. Other sites were found no correlation with male infertility. The cause for male infertility is a multi-factorial and still needs larger samples for deeper analysis according to the different ethnic backgrounds, environmental exposure or other fisk factors to analytically subclassify, the relationship of PRM1/PRM2 with male infertility deserves to further study.