The role of vitamin D receptor gene polymorphisms in gestational diabetes mellitus susceptibility: a meta-analysis

Association of VDR gene variant rs2228570-FokI with gestational diabetes mellitus susceptibility in Arab women

Gestational diabetes mellitus (GDM) has been linked with adverse pregnancy outcomes. Vitamin D receptor (VDR) gene variants have been associated with diabetes mellitus susceptibility and related complications. This study assessed the association between VDR gene polymorphism (rs2228570) and GDM risk among pregnant Arab women. A total of 368 pregnant Saudi women who were screened for GDM at 24-28 weeks of gestation and genotyped for the VDR gene variant (rs2228570) were included in this cross-sectional study. Circulatory insulin levels, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), and vitamin D (25(OH)D) were measured. There were 108 women with GDM and 260 women without GDM. The genotype frequency of women with GDM was CC 60.2 %, CT 33.3 %, TT 6.9 %, and CT + TT 39.8 %; for non-GDM women, were CC 61.1 %, CT 31.5 %, TT 6.9 %, and CT + TT 38.4 %. No association was found between the VDR gene variant (rs2228570-FokI) and GDM susceptibility after adjustment for covariates. Serum 25(OH)D had a significant inverse association with FBG (r = -0.49, p = 0.01) and HbA1c (r = -0.45, p = 0.03) among carriers of the TT-genotype. Furthermore, a significant inverse correlation was observed between serum 25(OH)D and HOMA-β (r = -0.20, p = 0.035) in individuals with the T-allele. Among pregnant Saudi women, glycemic indices appear to be influenced by vitamin D, suggesting a possible role it may play in mitigating the metabolic changes associated with GDM, particularly among individuals with specific genetic backgrounds. In our study population, rs2228570-FokI did not appear to be a significant contributor to GDM risk.

Diabetes and vitamin D: The effect of insulin sensitivity and gut microbial health

Current global estimation suggests that about 10% of adults worldwide have diabetes, thus, various strategies are needed to address the issue, including dietary factors such as vitamin D. Various studies have suggested an inverse associations between vitamin D and the risks and pathogenesis of all forms of diabetes (type 1, type 2 and gestational diabetes). The underlying mechanism is not fully understood; however, the expression of vitamin D receptors in pancreatic beta cells suggests an important physiological role for vitamin D in beta cell function. Vitamin D deficiency may impair blood glucose control and decrease insulin sensitivity by reducing insulin secretion from beta cells. Many studies suggest that vitamin D intervention may be beneficial; however, there is inconclusive evidence of the effectiveness of vitamin D supplementation on reducing the risks or managing the pathogenesis of all forms of diabetes. Part of the pathogenesis of vitamin D for reducing diabetes is thought to be related to its impact on gut microbiota profile, via the suggested prebiotic properties of vitamin D.

Lactogenesis factors in the Asian population

The increasing incidence of disrupted lactogenesis in Asian populations underscores the importance of timely identification and efficient intervention. This study acknowledges the influence of ethnicity on genetic variations and aims to investigate the genetic mechanisms that contribute to lactogenesis in individuals of Asian descent. This study examines the possibilities of genetic screening as a means of applying preventive measures, with a particular focus on epigenetic techniques. Additionally, the analysis looks into the underlying mechanisms involved in milk production. This review discusses the intricate mechanisms underlying breast milk production and the potential influence of genetic variables on lactogenesis. Specifically, it explores the association between lactogenesis issues and genetic conditions such as depression, obesity, gestational hypertension, and gestational diabetes. These genetic factors could potentially be found by genetic screening as contributors to disruption in lactogenesis. This study aims to promote future investigation in the subject of genetic testing and its potential association with lactogenesis issues, despite the current scarcity of direct research on this topic. The statement posits that the progress made in genetic testing has the potential to provide novel insights into the timely identification and treatment of disrupted lactogenesis.

Impact of vitamin D resistance genes on vitamin D deficiency during pregnancy among the South Indian population

Increasing evidence suggests that vitamin D (Vit-D) could be pivotal in maintaining normal glucose homeostasis. Low levels of Vit-D in early pregnancy are associated with a higher risk of gestational diabetes mellitus (GDM). Though several reports have highlighted the prevalence of vit-D deficiency among pregnant women, its underlying cause has not yet been fully elucidated. In this connection, a few studies have found the development of resistance to Vit-D, including the levels of Vitamin D receptor (VDR) and transcription regulators that modify VDR action, as well as the bioavailability of Vit-D. We aimed to determine the levels of Vit-D resistance genes such as 25-HydroxyVit-D-24-hydroxylase (CYP24A1), VDR repressor genes (SNAIL and SMRT) and their association between Vit-D concentrations in early pregnancy, and the risk of gestational diabetes mellitus (GDM). A prospective observational study was conducted on healthy pregnant women (NGDM; n = 50) and GDM (n = 50) attending routine antenatal care at SRM Medical College Hospital, Chennai, recruited at 12 weeks of gestation. We found that the serum levels of Vit-D were low in GDM subjects and negatively correlated with the fasting glucose levels. Further, increased expressions of Vit-D resistance genes such as CYP24A1, SNAIL, and SMRT were observed in GDM subjects and negatively correlated with the serum levels of Vit-D. Furthermore, we have validated the data using the trophoblast cell line, BeWo, exposed to calcitriol under a hyperglycemic environment. Our finding showed that increased expression of Vit-D resistance genes in pregnancy may be associated with a greater risk of adverse pregnancy outcomes, including GDM.

Relevance of Serum Levels and Functional Genetic Variants in Vitamin D Receptor Gene among Saudi Women with Gestational Diabetes Mellitus

Background: This study explored the association between ApaI-TaqI Single Nucleotide Polymorphisms (SNPs) in a Vitamin D receptor (VDR) and the risk of Gestational Diabetes Mellitus (GDM) in Saudi women, along with the serum levels of vitamin D. Methods: Ninety women with GDM and 90 non-GDM women were enrolled, based on the inclusion and exclusion criteria for pregnant women enrolled in a single-center study. Blood samples were retrieved from 180 pregnant women using ethylenediaminetetraacetic acid (EDTA) tubes. Serum samples were used to measure the vitamin D, 25-hydroxyvitamin D (25(OH)D or calcidiol), and lipid profiles. Blood was used to measure the hemoglobin A1c levels and to isolate the DNA. The polymerase chain reaction (PCR) was performed for the ApaI (rs79785232), BsmI (rs1544410), FokI (rs2228570), and TaqI (rs731236) SNPs in the VDR gene using restriction fragment length polymorphism analysis. Validation was performed using Sanger sequencing. Statistical analyses were performed between the patients with and without GDM using various statistical software packages. Results: The Hardy-Weinberg equilibrium analysis was statistically significant (p > 0.05). The ApaI, BsmI, and TaqI SNPs were associated with alleles, genotypes, and different genetic models (p < 0.05). Vitamin D levels were associated with deficient levels (p = 0.0002), as well as with a normal and overweight body mass index (p = 0.0004). When vitamin D levels were measured with GDM covariates, the fasting plasma glucose (FPG) (p = 0.0001), postprandial blood glucose (PPBG) (p < 0.0001), oral glucose tolerance test (OGTT)-1 h (p = 0.005), high-density lipoprotein (p = 0.022), and low-density lipoprotein cholesterol (LDLc) (p = 0.001) levels were significantly different. When similar vitamin D levels were measured for each genotype, we confirmed that the ApaI SNP was associated with sufficient levels (p < 0.0001), whereas the BsmI, FokI, and TaqI (p < 0.05) were associated with insufficient levels. The logistic regression model confirmed that the first hour of the OGTT (p = 0.005) was strongly associated with GDM, whereas the analysis of variance confirmed that FPG and PPBG (p < 0.05) were strongly associated with all the SNPs evaluated in the VDR gene. Additionally, the second hour of the OGTT (p = 0.048) and LDLc (p = 0.049) were associated with the ApaI and FokI SNP. Moreover, the first hour OGTT (p = 0.045) and lipid profile parameters (p < 0.05) were associated. Haplotype analysis revealed positive associations among the examined SNPs, which seemed compatible with the hypothesis that variants and combinations of multiple SNP genotypes enhance the risk of GDM in women. Haplotype analysis revealed that different combinations of alleles, such as AGCC, CATT, CGTC, AGTC, and CATT (p < 0.05), were strongly associated. The linkage disequilibrium (LD) analysis showed a strong association with all combinations (p < 0.05). Among the gene-gene interactions, all possible combinations showed a positive association (p < 0.05). Conclusions: Low vitamin D levels were observed in women with GDM. The ApaI, BsmI, and TaqI SNPs were associated with genotype and allele frequencies (p < 0.05). Vitamin D and the SNPs in the VDR gene were associated, according to the ANOVA, logistic regression, haplotype analysis, LD analysis, and the generalized multifactor dimensionality reduction model (p < 0.05).

Fok I and Bsm I gene polymorphism of vitamin D receptor and essential hypertension: a mechanistic link

The vitamin D receptor (VDR) gene serves as a good candidate gene for susceptibility to essential hypertension. The gene regulates the renin angiotensin system by influencing blood pressure regulation. Around 3% of the human genome is regulated by the vitamin D endocrine system. Several studies have reported mixed results with respect to relationship of VDR gene and hypertension. Observational evidence supports the concept that vitamin D plays a role in the pathogenesis of cardiovascular disease and arterial hypertension which is further supported by meta-analysis and case control studies reporting how VDR polymorphism leads to the onset and development of hypertension. In this review, we summarize the existing literature on the link between VDR and hypertension, including mechanistic studies, observational data, and clinical trials showing relationship of vitamin D level and hypertension with a focus on recent findings related to genetic studies that showed the relationship of VDR gene polymorphism with vitamin D level in hypertensive and normotensive groups. As a result, determining the association of VDR polymorphisms with essential hypertension is expected to aid in the risk assessment for the condition.

Beta-Cell Adaptation to Pregnancy - Role of Calcium Dynamics

During pregnancy, the mother develops insulin resistance to shunt nutrients to the growing fetus. As a result, the maternal islets of Langerhans undergo several changes to increase insulin secretion in order to maintain glucose homeostasis and prevent the development of gestational diabetes. These changes include an increase in β-cell proliferation and β-cell mass, upregulation of insulin synthesis and insulin content, enhanced cell-to-cell communication, and a lowering of the glucose threshold for insulin secretion, all of which resulting in an increase in glucose-stimulated insulin secretion. Emerging data suggests that a change in intracellular calcium dynamics occurs in the β-cell during pregnancy as part of the adaptive process. Influx of calcium into β-cells is crucial in the regulation of glucose-stimulated insulin secretion. Calcium fluxes into and out of the cytosol, endoplasmic reticulum, and mitochondria are also important in controlling β-cell function and survival. Here, we review calcium dynamics in islets in response to pregnancy-induced changes in hormones and signaling molecules, and how these changes may enhance insulin secretion to stave off gestational diabetes.