Environmental Factors,maternal CYP1A1 And CYP17A1 Polymorphisms,and Their Interaction In Hypospadias In Offspring

IntroductionHypospadias(HS)is a common birth defect of the genitourinary system,and it’s etiology is still unknown.Clinical surgery is the only treatment means for hypospadias.Although the overall treatment effect is improved with the improvement of surgical techniques,postoperative side effects such as urinary fistula and urethral stricture are still existing.Currently,most researchers believe that it is induced by gene-environment interaction.And many environmental risk factors that parents were exposed to associated with this congenital disease,such as toxic substances,drugs,diseases and abnormalities.Meanwhile,the susceptibility to HS also depends on individual genetic predisposition.However,the previous epidemiology studies mainly focused on the environmental risk factors,and did not pay attention to individual differences in susceptibility-.The present study aim to investigate the association of HS with the environmental risk factors and gene SNPs(CYP1A1 and CYP17A1)as well as the effect of gene-environment interaction on HS risk.Moreover,in order to reduce subjects’recall bias,researchers adopted qualitative indexes,which were easy to recall,to ensure the credibility of the questionnaire.The results of present study could provide some valuable information for the future therapy.Materials and Methods1.Collection of data and DNA samplesCases(152)were live born children diagnosed with HS at the Department of Pediatric Urology of Shengjing Hospital of China Medical University between August 2016 and September 2017.Controls(151)were randomly selected from the same hospital during the same period.Mothers were also invited to fulfill questionnaires concerning demographics,family history,health and lifestyle before and during pregnancy.Besides,our study was approved by the Ethics Committee of Shengjing Hospital of China Medical University and written informed consent was obtained from each participant.Case selection criteria were with isolated hypospadias according to the International Classification of Diseases(ICD)-11.Cases and controls with a syndrome or chromosome abnormality and cases with a known cause of hypospadias were excluded.The specific exclusion criteria were true hermaphroditism,chordee alone_and adrenogenital syndrome.DNA samples were extracted from the oral epithelial cells or saliva which collected from mothers of the subjects,and were genotyped for the polymorphisms of CYP1A1 and CYP17A1 by Taqman qPCR.Finally,a interaction analysis based on gene-environmental factors was carried out to explore the etiology of HS.2.Statistical analysisExcel 2007 was used to set up database.Univariable and multivariable logistic regression analyses were used to determine the risk factors.The CYP1A1 rs 1048943 and CYP17A1 rs4919686 genotypes frequencies in controls were tested by Hardy-Weinberg equilibrium(HWE),and P<0.05 was regarded as a significant deviation from HWE.The crude and adjusted odds ratios(ORs)with 95%confidence intervals(95%CIs)for the independent associations of HS with parental risk factors before and during pregnancy and maternal CYP1A1 rs 1048943,CYP17A1 rs4919686 genotypes were calculated by univariable and multivariable logistic regression analyses.Meanwhile,the role of interactions between parental risk factors and CYP1A1 rs1048943/CYP17A1 rs4919686 polymorphisms in the etiology of HS was also evaluated.Relative excess risk due to interaction(RERI)and attributable proportion due to interaction(AP)were calculated to assess interaction on an additive scale using the method proposed by Rothman et al.and Excel spreadsheet developed by Andersson et al.In order to get precise results of the present study,we considered maternal age at delivery,maternal residence during pregnancy as potential confounding factors in this analysis.And the risk estimation was adjusted by these confounding factors in both univariable and multivariable logistic regression analyses.SPSS 22.0 software for Windows(IBM SPSS,Chicago,IL,USA)was used to perform statistical analyses.ResultsLow birth weight(LBW)of infants,irregular menstruation,underweight Body mass index(BMI)(<18.5 kg/m2)before conception,passive smoking and lower education level of mothers,and occurrence of abnormalities during pregnancy were the risk factors of HS.The seldom exposure to passive smoking during pregnancy of mothers,higher education level of fathers and properly household income were the protective factors for HS.Genotype frequencies of CYP1A1 rs 1048943 and CYP17A1 rs4919686 polymorphisms were in HWE(P>0.05).The distribution of TT,TC and CC genotypes of CYP1A1 rs1048943 was 52.2%,39.2%and 8.6%respectively,and the distribution of AA,AC and CC genotypes of CYP17A1 rs4919686 was 58.8%,33.1%and 8.1%respectively.After adjusted for confounding factors,we found that the homozygous mutant genotype CC of CYP1A1 rs 1048943 significantly increased the risk of HS.In addition,homozygous mutant genotype CC and recessive genotype AC+CC of CYP17A1 rs4919686 revealed a significantly higher risk of HS in contrast to the AA genotype.Furthermore,the mutant allele C of CYP17A1 rs4919686 also showed an increased risk of HS.2×4 cross-tabs was adopted to detect the gene-environment interactions,meanwhile,"RR11-RR00>(RR10-RR00)+(RR01-RR00)" was defined as additive gene-environment interaction-.Although both of the results of gene-environment interaction did not indicate any significant difference between the groups of case and control,the additive gene-environment interactions were found in several models,including interactions of CYP1A1 with irregular menstruation before conception,passive smoking before conception and occurrence of abnormalities during pregnancy,as well as interactions of CYP17A1 with occurrence of abnormalities during pregnancy and paternal educational level.Conclusion1.LBW of infants,irregular menstruation,underweight BMI before conception,passive smoking and lower education level of mothers,and occurrence of abnormalities during pregnancy increase the risk of HS.2.The seldom exposure to passive smoking during pregnancy,higher education level of fathers and properly household income decrease the risk HS.3.Mother with gene polymorphisms of CYP1A1 and CYP17.A1 can increase the risk of HS.4.Gene-Environment addictive interaction were observed and can increase the risk of HS.