Association Of Interleukin-31 Gene Polymorphisms With Risk Of Cryptorchidism In A Chinese Han Population

Objective:The single nucleotide polymorphisms(SNPs)of Interleukin-31(IL-31)gene rs4758680,rs7977932 sites in patients with cryptorchidism and healthy people in a Chinese Han population were analyzed,in order to learn the allele and genotype distribution in SNPs of IL-31 gene rs4758680,rs7977932,and to further investigate the relationship between SNPs of IL-31 gene rs4758680,rs7977932 sites and genetic susceptibility to cryptorchidism.Materials and methods:Patients with confirmed cryptorchidism were selected as case group in our study,who were hospitalized in the Affiliated Hospital of North Sichuan Medical College from January 2010 to December2015.And unrelated healthy people who presented for resection for foreskin were recruited as control group.Premature or low birth weight infants and individuals with personal or family history of systemic diseases or other serious diseases were not included in this study.The peripheral venous blood samples of the subjects were collected.Amplify the target gene fragments after the genomic DNA was extracted.Polymerase chain reaction-restriction fragment length polymorphism and polyacrylamide gel electrophoresis methods were used to genotype the SNPs of rs7977932,rs4758680 sites in IL-31 gene.Student′s t-test was used to compare baseline data(birth weight,gestational weeks)of the case and the control group.Chi-square(χ~2)test was used to test Hardy-Weinberg genetic balance in healthy control population and to compared the allele and genotype frequencies between the case group and the control group.Analyses of the relationship between SNPs of IL-31gene and genetic susceptibility to cryptorchidism in different genetic models were performed by logistic regression analysis.The statistical results were presented as odds ratio(OR)and 95%confidence interval(CI).p<0.05means the difference is statistically significant.Results:The birth weight of the case group and the control group were3393.2±451.7 gram and 3363.1±508.1 gram respectively.The gestational weeks of the case group and the control group were 39.9±1.6 weeks and39.6±1.4 weeks respectively.There were no statistical differences in base line data between two study groups.SNPs of rs7977932 and rs4758680 of112 cases with cryptorchidism and 425 controls were genotyped successfully.The genotype distribution of the control group was in accordance with the Hardy-Weinberg balance.There was no significant difference in the allele and genotype distribution in SNPs of IL-31 gene rs7977932 site between the case group and the control group(p>0.05).The frequencies of A allele of rs4758680 site in the patients with cryptorchidism were significantly decreased compared with those in the controls(10%versus 17%,OR=0.58,95%CI 0.37-0.92,p=0.02).Compared with CC genotype in dominant model,the frequencies of CA/AA genotype in the case group were significantly lower than those in the control group(20.5%versus 30.8%,OR=0.58,95%CI:0.35-0.96,p=0.03).Conclusion:The SNPs of IL-31 gene rs4758680 site have an association with genetic susceptibility to cryptorchidism in a Chinese Han population.Compared with C allele of rs4758680 site,A allele was significantly associated with the decreased risk of cryptorchidism.In the dominant model,A allele carriers(CA/AA genotypes)of rs4758680 were protective factors in cryptorchidism susceptibility.