Vitamin D receptor (VDR) polymorphisms are associated to spontaneous preterm birth and maternal aspects

Preterm birth (PTB) is featured by less than 37 weeks of gestational age or fewer than 259 days since the first day from the last menstrual period. Complications of PTB are the major cause of neonatal deaths, several factors are linked to PTB increased risk including immunological and genetics. Vitamin D plays an important role in immune response modulation and its action occurs through the vitamin D receptor (VDR), which recently has been described as overexpressed in human placenta during the pregnancy. Herein we assessed two single nucleotide polymorphisms (SNPs) FokI (rs2228570 A>G) and Cdx-2 (rs11568820 T>C), within VDR, using TaqMan fluorogenic probes, and differential susceptibility to SPTB. We assessed 104 pregnant women with SPTB and 85 women with normal birth in a Northeastern Brazilian population. Statistically significant differences for both SNPs where found when comparing allele and genotype frequencies in both groups: the T allele for rs2228570 and A allele for rs11568820 were significantly more frequent in SPTB group than in normal birth group (p=0.000013 and p=0.00466, respectively). The rs11568820 A/A genotype was associated to clinical/demographic variables such as: premature birth (p=0.007), neonate weight (p=0.039), presence of infection during pregnancy (p=0.011) and premature birth among multiparous (p=0.015). The rs2228570 T/T genotype associated with gestational diabetes mellitus (p=0.044) and chorioamnionitis during pregnancy (p=0.043). In conclusion our findings indicate an association between polymorphisms FokI and Cdx-2 within VDR gene and SPTB, suggesting their involvement in the triggering of these syndrome.