Vitamin D and Recurrent Abortion: Inference through several Vitamin D Receptor (VDR) Gene Polymorphisms and Vitamin D Status among the Inflicted Palestinian Women رسالة ماجستير

Abstract

Background and objectives: Recurrent pregnancy loss (RPL) is a complicated medical status affecting 1–4% of women during reproductive age. It occurs when a woman repeatedly loses her fetus before it reaches 20 weeks of gestation. In Palestine, the prevalence of RPL is not determined among Palestinian females due to the absence of any study regarding this matter. Recently, selected variants in the VDR gene have been linked to RPL in some populations. Hence, our study aimed to investigate whether two maternal SNPs of the VDR gene, specifically (rs2228570) and (rs1544410), and the level of vitamin D status may be involved in the etiology of RPL among inflicted Palestinian women. Methods: A total of 131 females were enrolled in this study. The case group consisted of 51 women who experienced at least three consecutive miscarriages in the second trimester, while the control group consisted of eighty women with two or more full-term successful pregnancies. DNA samples were obtained and genotyped for VDR rs2228570 and rs1544410 polymorphisms using PCR- restriction fragment length polymorphism (PCR-RFLP). The serum 25-hydroxyvitamin D3 level was measured. Additionally, within the case group, two females had a familial history of RPL and were subjected to whole exom sequencing. The confirmed variants were analyzed by In Silico bioinformatic tools. Results: Significant differences in allele and genotype frequencies were observed among study subjects in the VDR rs1544410 polymorphic site (G vs. A p-value = 0.05, GG vs. GA p-value = 0.01, GG vs. AA p-value = 0.02). The risk of developing RPL increased under the dominant genetic model (GG vs. total A, p-value = 0.006). No statistically significant differences in allele and genotype frequencies were observed among study VI subjects in the VDR rs2228570 polymorphic site. Since, the T-G haplotype was more frequent in the control group than the case group therefore it was associated with RPL prevention (P-value = 0.023). No statistically significant association was observed between serum 25-hydroxyvitamin D3 levels and study subjects since the majority of subjects in the study suffer from VD deficiency. No statistically significant difference between serum 25-hydroxyvitamin D3 levels and both VDR SNPs (rs2228570 and rs1544410) genotypes was observed among study subjects. Regarding family analysis, two variants were identified in each family. In the first family, the FGA *787T>C and HLA-G Leu154fs*60 variants follow autosomal dominant inheritance and were positively confirmed and segregated well within the family, while in the second family, the F12 Arg55Trp failed to segregate within the family. Conclusions: The data revealed significant correlation between rs1544410 variant and RPL with no significant correlation with rs2228570 variant in the VDR gene. Serum VD levels did not alter this result which needs further assessment due to the VD deficiency status of all participating subjects. WES analysis of two RPL familial cases showed specific variants in FGA (*787T>C) and HLA-G (Leu154fs*60) are linked with the risk of recurrent abortion. This could be through influencing fetus stability, growth, and proceeding to full term, which needs further testing and confirmation.