Polymorphisms within vitamin D binding protein gene within a Preeclamptic South African population

Objectives: The vitamin D binding protein encoded by the GC gene contains two single nucleotide polymorphisms (rs4588 and rs7041) that have been associated with disease outcome, these include periodontitis coronary heart disease and hypertension. In pregnancy, these SNPs influence vitamin D metabolism that could result in hypertensive disorders such as PE. The etiology of PE, still remains elusive. The aim of this study was to evaluate the distribution of rs4588 and rs7041 within the GC gene among PE and normotensive pregnant women, residing in Durban, KwaZulu-Natal, South Africa. Study design: Our study consisted of n = 600 participants (normotensive (n = 246, N); early onset PE (n = 167, EOPE); and late-onset PE (n = 246, LOPE)). We extracted DNA from whole blood and genotyped for rs4588 and rs7041 SNPs using the TaqMan assay. Results: Regardless of HIV status, we observed the rs4588 (CC genotype) more frequently in PE (EOPE+LOPE) compared to the normotensive participants with an OD ratio of 0.74 (95% CI, 0.35-1.5; p < 0.001). We report a significant difference in the frequency of rs7041 (GT genotype) in the EOPE group compared to the normotensive group with an OD ratio of 11.48 (95% CI, 2.6-103.7; p < 0.001). The rs7041 GT genotype had a higher frequency in the EOPE compared to the LOPE group, with an OD ratio of 15.15 (95% CI, 2.3-639.2; p < 0.001). Conclusion: This is the first study to describe the prevalence of SNPs of the rs4588 and rs7041 within the GC gene in women with PE within the high HIV endemic area of KZN, South Africa. Notably, a significant association of the rs7041 (TT genotype) and rs4588 (CC genotype) occurred at a higher frequency in PE compared to the normotensive cohort. Future studies will examine the functional effect of the GC region in relation to pregnancy and vitamin D deficiency.