Discovering the missense variant allele in rs7041 of GC gene among individuals with low serum vitamin D

Open Access

Abstract

Background: Vitamin D deficiency is a global health concern affecting more than a billion people and is increasingly recognized in tropical countries like Bangladesh despite adequate sunlight. Genetic variations, particularly in the Group-specific component (GC) gene encoding vitamin D binding protein (DBP), may influence serum vitamin D levels. The present study aimed to investigate the association of rs7041 polymorphism of the GC gene with serum vitamin D status among healthy Bangladeshi adults. Methods: This cross-sectional study was conducted at the Department of Physiology, Dhaka Medical College, from July 2019 to June 2020. A total of 59 healthy adults were screened for serum vitamin D, of whom 32 with low levels (<30 ng/ml) were included as the study population and 10 with normal levels as controls. Socio-demographic, anthropometric, and biochemical data were collected. Genotyping of rs7041 of the GC gene was performed at the Center for Medical Biotechnology (CMBT), Mohakhali, using PCR, agarose gel electrophoresis, purification, and sequencing. Statistical analysis was carried out with chi-square testing, with p<0.05 considered significant. Results: The mean serum vitamin D level of the study population was 18.91 ± 4.86 ng/ml compared to 49.23±16.29 ng/ml in controls. The allele frequency distribution of rs7041 among the study population revealed major allele T (59.4%) and minor allele G (40.6%) with a minor allele frequency of 0.406. In controls, allele T was 45% and allele G was 55%. The chi-square test showed no statistically significant difference in allele distribution between study and control groups (p=0.258). However, low serum vitamin D was observed more frequently in carriers of the T allele. Conclusions: The findings suggest a possible association of the rs7041 T allele of the GC gene with low serum vitamin D levels in Bangladeshi adults, despite adequate sun exposure. This highlights the importance of genetic determinants in vitamin D status and suggests the need for further large-scale studies to better define population-specific reference ranges and risk groups.