Association between Genetic Variants of GC Gene at 4q13.3 and Vitamin D Concentrations in Adult Females

Abstract

Background: Vitamin D binding protein, encoded by the GC gene (on 4q13.3), plays an important role in transporting vitamin D. Several Genome-Wide Association Studies (GWASs) have established a significant association between variants of GC gene and circulating vitamin D. Objective: This study aims to determine the association of GC gene polymorphisms with vitamin D concentrations in young healthy Arab females. Methodology: 214 female subjects from Qatar University were enrolled in this cross-sectional study. The cut-off value for optimal vitamin D levels was set at 30 ng/mL. The serum vitamin D was measured using ELISA, the genotyping of SNPs (rs2298850, rs3755967, rs2282679, rs7041, rs1155563, and rs17467825) of GC gene was performed by TaqMan assay, and the data was analyzed using SPSS software. Results: The mean age of 214 participants was found to be 21.97 years. Of these, only 182 subjects were included in this study. The data showed that 14.8% were found to have optimal vitamin D levels and 85.2% with suboptimal levels. All studied SNPs were in HWE except SNPs rs7041 and rs1155563. Using the dominant model for rs2298850, the odds ratio to have low vitamin D is 1.48 (p=0.419). Similarly, rs3755967 has a risk of 1.62 (p=0.294); rs2282679 has an odds ratio of 1.32 (p=0.549); and rs17467825 with a risk of 1.48 (p=0.40). The genotypes for vitamin D levels had no significant difference (p>0.05) for all study subjects. Conclusion: The current data showed no significant association between risk alleles of SNPs (rs2298850, rs3755967, rs2282679, rs7041, rs1155563, and rs17467825) with vitamin D levels. Keywords: Vitamin D deficiency; 25-hydroxyvitamin D; GC gene; Vitamin D binding protein; SNPs Abbreviations: 25-hydroxyvitamin D/calcifediol (25-(OH)D); 1, 25-dihydroxyvitamin D/calcitriol (1,25-(OH)2D); Vitamin D Binding Protein (DBP); Group-specific Component (GC); Ultraviolet radiation B(UVB); Vitamin D Receptor (VDR); Retinoid X Receptor (RXR); Parathyroid Hormone (PTH); DNase Hypersensitivity Site (HSIV); Single Nucleotide Polymorphisms (SNP); Chemiluminescent Immunoassay (CLIA); Chemiluminescent- Microparticle Immunoassay (CMIA); Enzyme Linked Immunosorbent Assay (ELISA); High Performance Liquid Chromatography (HPLC); Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS); Body Mass Index (BMI); Overweight and Obese (OWOB); Waist Circumference (WC); Low Density Lipoprotein (LDL); High Density Lipoprotein (HDL); Triglycerides (TG); Interleukin-6 (IL-6); Minor Allele Frequency (MAF); Hardy-Weinberg Equilibrium (HWE); Confidence Intervals (CI); Analysis of Variance (ANOVA)