Protective association of VDR gene polymorphisms and haplotypes with multiple sclerosis patients in Egyptian population

A review of the critical role of vitamin D axis on the immune system

In recent years, the physiological and molecular functions of vitamin D (Vit-D) have been deeply investigated. At first, Vit-D was considered a regulator of mineral and skeletal homeostasis. However, due to the extensive-expression pattern of Vit-D receptor (VDR) in almost every non-skeletal cell, Vit-D is considered mainly a multifunctional agent with broad effects on various tissues, notably the immune system. The expression of VDR in immune cells such as dendritic cells, monocyte/macrophage, neutrophils, B cells and T cells has been well demonstrated. Besides, such immune cells are capable of metabolizing the active form of Vit-D which means that it can module the immune system in both paracrine and autocrine manners. Vit-D binding protein (DBP), that regulates the levels and homeostasis of Vit-D, is another key molecule capable of modulating the immune system. Recent studies indicate that dysregulation of Vit-D axis, variations in the DBP and VDR genes, and Vit-D levels might be risk factors for the development of autoimmune disease. Here, the current evidence regarding the role of Vit-D axis on the immune system, as well as its role in the development of autoimmune disease will be clarified. Further insight will be given to those studies that investigated the association between single nucleotide polymorphisms of DBP and VDR genes with autoimmune disease susceptibility.

Association of vitamin D receptor gene polymorphisms with type 2 diabetes mellitus in Taif population: a case-control study

Abstract Several reasons may underlie the dramatic increase in type2 diabetes mellitus. One of these reasons is the genetic basis and variations. Vitamin D receptor polymorphisms are associated with different diseases such as rheumatoid arthritis and diabetes. The aim of this study is to investigate the possible association of two identified mutations ApaI (rs7975232) and TaqI (rs731236). Eighty-nine healthy individuals and Fifty-six Type 2 Diabetic (T2D) patients were investigated using RFLP technique for genotyping and haplotyping as well. The distribution of Apal genotypes was not statistically significant among the control (P=0.65) as well as for diabetic patients (P=0.58). For Taql allele frequencies of T allele was 0.61 where of G allele was 0.39. The frequency distribution of Taql genotypes was not statistically significant among the control (P=0.26) as well as diabetic patients (P=0.17). Relative risk of the allele T of Apa1 gene is 1.28 and the odds ratio of the same allele is 1.53, while both estimates were < 1.0 of the allele G. Similarly, with the Taq1 gene the relative risk and the odds ratio values for the allele T are 1.09 and 1.27 respectively and both estimates of the allele C were 0.86 for the relative risk and 0.79 for the odds ratio. The pairwise linkage disequilibrium between the two SNPs Taq1/apa1 was statistically significant in control group (D = 0.218, D' = 0.925 and P value < 0.001) and similar data in diabetic groups (D = 0.2, D' = 0.875 and P value < 0.001). These data suggest that the T allele of both genes Apa1 and Taq1 is associated with the increased risk of type 2 diabetes. We think that we need a larger number of volunteers to reach a more accurate conclusion.

Association of Vitamin D receptor gene variations with Gastric cancer risk in Kashmiri population

Vitamin D receptor (VDR) mediates cellular processes like cell cycle arrest and apoptosis which effect cancer susceptibility. VDR single nucleotide polymorphisms (SNPs) have a significant influence on functioning of VDR protein and subsequently contribute to the risk of cancer occurrence and progression. The present case-control study was carried out between 2016 and 2020 to investigate the association of VDR BsmI/ApaITaqI SNPs with Gastric Cancer (GC) risk in ethnic Kashmiri population not only for establishing a molecular marker for GC but also to facilitate the outcomes of personalized medicine in future. The polymorphisms of BsmI and ApaI of the VDR gene were evaluated using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism followed by Di-Deoxy Sanger sequencing in 143 GC cases and 150 controls. The mean age (in years) was 53.5 ± 7.92 and 51.2 ± 8.25 and mean Body mass index was 22.68 ± 4.27 kg/m² and 23.81 ± 3.71 kg/m² for cases and controls respectively. The mean CEA levels of GC cases was 40.2 ± 10.9 ng/ml. Genotypic distribution of VDR BsmI differed significantly between GC cases and controls (GG vs GA + AA; adjusted P = 0.014) and followed dominant mode of inheritence. Stratification of VDR BsmI revealed that frequency of variant genotype (GA + AA) was significantly higher in Preobese GC cases (P = 0.001), GC patients consuming < 5 cups of salt tea/day (P < 0.0001) and with no family history of gastrointestinal cancer (P = 0.014) compared to healthy controls. ATC haplotype associated with high GC risk. In conclusion, our study suggests that VDR BsmI SNP has a significant association with increased risk of GC especially in preobese population and BsmI/ApaITaqI SNPs significantly decreased the overall survival in GC patients of Kashmiri population.