Polymorphisms of endocrine gland-derived vascular endothelial growth factor gene and its receptor genes are associated with recurrent pregnancy loss

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) and its receptor genes [prokineticin receptor 1 (PKR1) and prokineticin receptor 2 (PKR2)] have been identified in the last decade and their expression is restricted to the steroidogenic glands (ovary, testis, adrenal gland and placenta). Their expression patterns also suggest a close relationship to early pregnancy. However, little information is available regarding the role of EG-VEGF and its receptors (PKR1 and PKR2) in recurrent pregnancy loss (RPL). This study was conducted to investigate the association between polymorphisms of EG-VEGF and its receptor genes (PKR1 and PKR2) and idiopathic RPL. In this case-control study, 115 women with a history of idiopathic RPL and 170 controls were included. A total of 11 tag single nucleotide polymorphisms (SNPs) selected from EG-VEGF, PKR1 and PKR2 were genotyped. We further used multifactor dimensionality reduction (MDR) analysis to choose a best model and evaluate gene-gene interactions. Two tag SNPs of PKR1 (rs4627609, rs6731838) and one tag SNP of PKR2 (rs6053283) were significantly associated with idiopathic RPL (P < 0.05). The frequencies of haplotypes C-G and T-A of PKR1 and haplotype A-G-C-G-G of PKR2 were significantly increased in women with idiopathic RPL (P < 0.05); MDR tests revealed gene-gene interactions between three loci [EG-VEGF (rs7513898), PKR1(rs6731838), PKR2(rs6053283)] based on the association model (P = 0.008). The adjusted odds ratio of high- and low-risk genotype combinations in the three-locus model was 3.94 (95% confidence interval: 2.38-6.52). EG-VEGF receptor (PKR1, PKR2) gene polymorphisms and haplotypes were associated with idiopathic RPL. These three genes (EG-VEGF, PKR1 and PRK2) jointly contribute to RPL in the Taiwanese Han population.