Influence of Apa1 (rs7975232), Taq1 (rs731236) and Bsm1 (rs154410) polymorphisms of vitamin D receptor on preterm birth risk in the Polish population

Objectives: Vitamin D receptor (VDR) is expressed in the placenta and tissues related to the immune system occurrence of various variants of VDR may modify the effects of vitamin D on pregnancy. The aim of this study was to evaluate the association between the parturients' Apa1, Taq1, and Bsm1 polymorphisms of the VDR and their combinations and the risk of preterm birth in the Polish population. Material and methods: Determination of polymorphism for VDR was assayed using the RT-PCR method. 199 Caucasian women at childbirth were qualified: 100 patients who had a spontaneous preterm birth and 99 patients who had a term birth. Results: Three separate genotypes of the Apa1, Taq1, and Bsm1 polymorphisms were detected. No significant differences in the frequency of particular genotypes in the compared groups were found. Some of the genotype combinations were significantly more frequent in the preterm group - the bb/AA/TT genotype (28.0% vs. 10.1%; p = 0.0013) and the BB/aa/tt genotype (14.0% vs. 4.04% p = 0.0277). The Bb/AA/Tt and the BB/Aa/tt genotypes were found only in the control group (16.1% and 7.0% of patients, respectively). The bb/aa/TT was significantly more frequent in the control group (2.0% vs. 11.1%; p = 0,0207). Two genotype combinations reduced the risk of preterm birth - the Bb/AA/Tt genotype by 94% (OR = 0.43, 95% CI: 0.002- 0.885, p = 0.041) and the BB/Aa/tt genotype by 98% (OR = 0.029, 95% CI: 0.001-0.838, p = 0.039). Conclusions: Our result suggests that there may be a relationship between certain VDR genotype combinations and the risk of preterm birth. Further research is needed in order to substantiate this finding.