Association Between Vitamin D Metabolism Related Gene Polymorphisms And Recurrent Spontaneous Abortion

PurposeSome studies have reported that vitamin D deficiency was associated with recurrent spontaneous abortion（RSA）,indicating that vitamin D may play a role in the development of RSA.Cytochrome P450 family 2subfamily R member 1（CYP2R1）and vitamin D receptor（VDR）are two genes which are vital for metabolizing vitamin D into its biological active form and exerting functions.However,it is unclear whether single nucleotide polymorphisms（SNPs）of the two vitamin D metabolism related genes are associated with the risk of RSA.Hence,this study aimed to investigate the association between CYP2R1 and VDR SNPs and RSA.Meanwhile,we attempted to explore the relationships among vitamin D,related cytokines,SNPs and RSA.MethodsThis study was designed as a case-control study,we collected relevant basic informations from patients with RSA and control women,and collected their blood samples.Serum vitamin D levels were detected with LC-MS/MS,serum calcium concentrations were detected with methyl thymol blue colorimetry,while serum levels of related cytokines（IL-2,4,6,10,IFN-γ,TNF-α）were detected with flow cytometry.Gene sequencing for three SNPs of CYP2R1（rs10741657,rs10766197 and rs12794714）and five SNPs of VDR（rs7975232,rs1544410,rs2189480,rs2228570 and rs2239179）was done with multiple polymerase chain reaction（PCR）and high-throughput sequencing technology.All collected basic informations and experimental data were statistically analyzed using appropriate methods and models.Results（1）The age,gestational week,serum levels of VD,VD₂,IL-6 and calcium were significantly higher in RSA group than in control group;RSA group also had significant higher incidence of abnormal TNF-αlevel（>4.5pg/m L）than control group.（2）Both serum levels of VD and VD₂were positively correlated to serum IL-6 levels;there was a positive correlation between serum levels of VD₂and calcium.（3）After adjusting for age and gestational week,the results showed that serum levels of VD₂,calcium and the incidence of abnormal TNF-αlevel were associated with an increased risk of RSA（OR:4.282,77.691,24.242;95%CI:1.789-10.253,5.465-1104.436,2.344-250.737;P=0.001,0.001,0.007）.（4）The logistic regression model was adjusted for age and gestational week.In RSA group,CYP2R1 rs10741657 AG and GG genotype were associated with both serum levels of VD and VD₃;there were significant associations between CYP2R1 rs12794714 AG and VD levels,and between VDR rs1544410 CT and IL-6 levels;VDR rs2189480 GG and rs2239179CC were significantly associated with IL-10 levels.In control group,VDR rs2228570 GG and AG were separately associated with VD₂and calcium levels;CYP2R1 rs10766197 GG was associated with calcium levels.（5）After adjusting for age and gestational week,the results showed that CYP2R1 rs12794714 AG and GG genotype were significantly associated with an increased risk of RSA（OR:52.394,59.497;95%CI:2.683-1023.265,3.110-1138.367;P=0.009,0.007）.（6）The haplotype GGG（rs10741657,rs10766197,rs12794714）of CYP2R1 was associated with a decreased risk of RSA（OR:0.516;95%CI:0.277-0.961;P=0.036）.There was an interaction between CYP2R1rs12794714 and VDR rs7975232,and this interaction was associated with an increased risk of RSA（OR:19.0909;95%CI:4.6563-78.2739;P=0.001）.ConclusionOur results indicate that CYP2R1 rs12794714 might be a risk factor for RSA.However,it is necessary to increase the sample size and use the functional experiments to clarify the relationship between the polymorphism of this locus and RSA,so as to determine whether it can be used as a marker for early screening and diagnosis of RSA.