Association of maternal VDR and VDBP gene polymorphisms with spontaneous preterm birth risks: a nested case–control study in China

The impact of vitamin D on spontaneous preterm birth (SPTB) is still not well understood. This study aimed to explore the relationship between maternal vitamin D receptor (VDR) and vitamin D-binding protein (VDBP) gene polymorphisms, as well as gene-gene interactions, and their potential association with the risks of SPTB. A nested case-control study involving 200 pregnant women with SPTB and 199 controls with full-term delivery was performed. A total of eight maternal single nucleotide polymorphisms (SNPs) were genotyped, including those in the VDR gene at the rs731236, rs7975232, rs1544410, rs2228570, rs10783219, and rs11568820 loci, as well as those in the VDBP gene at the rs4588 and rs7041 loci. The multivariate logistic regressions were used to estimate the association between VDR and VDBP gene polymorphisms, including alleles, genotypes and haplotypes, and the risks of SPTB. Generalized multifactor dimensionality reduction (GMDR) was used to identify gene–gene interactions. Among eight SNP loci, none of the minor alleles showed a significant association with the risks of SPTB. Additionally, the variant genotypes of these eight SNPs were not associated with the risks of SPTB under additive, dominant, and recessive genetic patterns. Moreover, three haplotypes in VDR gene and three haplotypes in VDBP gene were identified, but none of them demonstrated a significant association with the risks of SPTB. Lastly, no significant gene-gene interactions among the different SNPs were found to influence the risks of SPTB. Common maternal polymorphisms in the VDR and VDBP genes were not significantly associated with the risks of SPTB, and no significant gene-gene interactions related to SPTB were observed.