Relationship between vitamin D receptor BsmI and FokI polymorphisms and anthropometric and biochemical parameters describing metabolic syndrome

Molecular effects of Vitamin-D and PUFAs metabolism in skeletal muscle combating Type-II diabetes mellitus

Multiple post-receptor intracellular alterations such as impaired glucose transfer, glucose phosphorylation, decreased glucose oxidation, and glycogen production contribute to insulin resistance (IR) in skeletal muscle, manifested by diminished insulin-stimulated glucose uptake. Type-2 diabetes mellites (T2DM) has caused by IR, which is also seen in obese patients and those with metabolic syndrome. The Vitamin-D receptor (VDR) and poly unsaturated fatty acids (PUFAs) roles in skeletal muscle growth, shapes, and function for combating type-2 diabetes have been clarified throughout this research. VDR and PUFAs appears to show a variety of effects on skeletal muscle, in addition it shows a promising role on bone and mineral homeostasis. Individuals having T2DM are reported to suffer from severe muscular weakness and alterations in shape of the muscle. Several studies have investigated the effect on VDR on muscular strength and mass, which leads to Vitamin-D deficiency (VDD) in individuals, in which most commonly seen in elderly. VDR has been shown to affect skeletal cellular proliferation, intracellular calcium handling, as well as genomic activity in a variety of different ways such as muscle metabolism, insulin sensitivity, which is the major characteristic pathogenesis for IR in combating T2DM. The identified VDR gene polymorphisms are ApaI, TaqI, FokI, and BsmI that are associated with T2DM. This review collates informations on the mechanisms by which VDR activation takes place in skeletal muscles. Despite the significant breakthroughs made in recent decades, various studies show that IR affects VDR and PUFAs metabolism in skeletal muscle. Therefore, this review collates the data to show the role of VDR and PUFAs in the skeletal muscles to combat T2DM.

Association of FHL5 and LPA genetic polymorphisms with diabetes mellitus risk: a case-control study

BACKGROUND

China is one of the countries with the fastest growing prevalence of diabetes mellitus (DM) in the world. This study intended to investigate the association of single nucleotide polymorphisms (SNPs) of FHL5 and LPA with DM risk in the Chinese population.

METHODS

This case-control study involved 1,420 Chinese individuals (710 DM patients and 710 controls). Four candidate loci (rs2252816/rs9373985 in FHL5 and rs3124784/rs7765781 in LPA) were successfully screened. The association of SNPs with DM risk was assessed by logistic regression analysis. Differences in clinical characteristics among subjects with different genotypes were analyzed by one-way analysis of variance.

RESULTS

Overall analysis indicated that rs3124784 was associated with an increased risk of DM. Stratification analysis showed that rs3124784 significantly increased DM risk in different subgroups (male, non-smoking, non-drinking, and BMI > 24), while rs7765781 increased DM risk only in participants with BMI ≤ 24. Rs2252816 was associated with the course of DM. We also found that rs2252816 GG genotype and rs9373985 GG genotype were linked to the increased cystatin c in DM patients.

CONCLUSION

The genetic polymorphisms of LPA may be associated with DM risk in the Chinese population, which will provide useful information for the prevention and diagnosis of DM.

Level of biochemical parameters in patients with type 2 diabetes mellitus depending on the genotype of the FokI polymorphism in the vitamin D3 receptor (VDR gene)

OBJECTIVES

Diabetes mellitus type 2 (T2DM) is a multifactorial and polygenic disorder characterised by chronic hyperglycaemia accompanied by impaired lipid, carbohydrate, and protein metabolism. The disease is associated with several genetic polymorphisms, including the FokI polymorphism in the vitamin D receptor (VDR) gene.

METHODS

We conducted a study of 327 probands (191 T2DM patients, 136 controls), with a mean age 65.06 (SD ± 10.88) years of patients with T2DM and 58.89 (SD ± 6.59) years in the healthy probands. We investigated the association between FokI polymorphism and biochemical parameters in T2DM patients in the Slovak population. Anthropometric measurements, biochemical, and genetic analysis were statistically evaluated by Statistica ver.13 software using t-tests.

RESULTS

Biochemical analysis confirmed significantly higher mean values of total cholesterol (TC), triglyceride (TG), glucose (GLU), and uric acid (UA) (p < 0.001) in T2DM probands and statistically significantly lower values of high-density lipoprotein (HDL), cholesterol and vitamin D (p < 0.001). Allele frequencies and genotype distributions of the FokI (rs2228570) polymorphism were not significantly different between T2DM patients and controls (p = 0.909). Patients with T2DM and TT genotype had the highest glucose level of 11.39 (SD ± 2.32) uU/ml (p < 0.001).

CONCLUSION

Our study did not provide evidence for an association of the investigated FokI polymorphism of the VDR gene with T2DM in the Slovak population. Further research is needed to evaluate the impact of single nucleotide polymorphisms (SNPs) in the VDR gene, focusing on related genetic analyses in a larger T2DM cohort.

Differences in Chronic Low-Grade Inflammation and Metabolic Disturbances between VDR Genotypes in an Ethnically Homogenous Postmenopausal Female Population from Poland

(1) Vitamin D deficiency and changes in the endocrine system may stimulate systemic inflammation. VDR expression and the vitamin D concentration decrease with age, which is important in postmenopausal women for whom estrogen deficiency causes rapid bone loss. This group is, moreover, particularly at risk of developing atherosclerosis and its adverse consequences, such as chronic inflammation. The aim of this study was to assess the differentiation by the VDR genotype of the risk factors for so-called chronic low-grade inflammation and metabolic disorders. (2) We studied the differences between the anthropometric, metabolic, and inflammation parameters of VDR genotypes for Apa-I, Bsm-I, Fok-I, and Taq-I in a sample of 321 women aged 50-60 from an ethnically homogeneous urban population in Poland. (3) The TT Taq-I genotype presented a significantly higher rate of insulin resistance (HOMA) and lower serum levels of adiponectin than the other two genotypes. The AA genotype of the Bsm-I polymorphism was associated with a more atherogenic serum profile and significantly higher LDL and LDL/HDL values and Castelli Index. (4) Chronic low-grade inflammation was associated with the TT Taq-I genotype and presented a higher rate of insulin resistance. The AA genotype of the Bsm-I polymorphism presented a more atherogenic serum lipid profile and, therefore, a higher risk of developing cardiovascular disease.

A comprehensive insight into the potential roles of VDR gene polymorphism in obesity: a systematic review

Vitamin D receptor (VDR) gene polymorphisms are believed to be involved in the obesity pathogenesis. This study summarises the results of research concerning the association between VDR polymorphisms and obesity. For this survey, the records of common databases were searched until November 2019. Four loci of the VDR gene in four case-controlled and 22 cross-sectional studies were assessed and evaluated. In the case-control studies, no significant association was observed between ApaI and FokI polymorphism with obesity risk. TaqI "T" allele in two studies was related to a higher risk of obesity. One investigation found no relationship between BsmI and obesity, while another article suggested that the "b" allele is more frequently found in obese subjects. The results of cross-sectional studies did not lead to consistent findings. Although the previous studies failed to arrive at conclusive findings, the effects of VDR polymorphism on obesity development cannot be ignored.

Vitamin D Receptor Gene ApaI and TaqI Polymorphisms in Type 2 Diabetes among Saudi Population

Background: Variants of vitamin D receptor (VDR) gene have been linked to a variety of diseases, including metabolic syndrome, cancer, bone disease, and tuberculosis. The relationship between VDR gene mutations and the susceptibility of type 2 diabetes mellitus (T2DM) in different ethnic groups is yet unknown. Vitamin D and its receptor complex have a function in regulating β-cell insulin secretion as a transcription factor. Objectives: The goal of this study was to see if there is a link between VDR Apa1 and Taq1 polymorphisms and T2DM susceptibility in the Saudis of Makkah environ. Materials and Methods: DNA was separated from peripheral blood and genotyped in 110 healthy controls and 110 unrelated people with T2DM for the VDR ApaI (G/T) rs7975232 and TaqI (A/G) rs731236 single nucleotide polymorphisms (SNPs) using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) technique. Results: The distributions of genotypes and alleles of VDR ApaI and TaqI polymorphisms were statistically indifferent across the groups investigated (P >0.05). Conclusion: These findings showed that polymorphisms in the VDR ApaI and TaqI genes may not be linked to T2DM risk in Saudis.

The interactive effect of vitamin D3 supplementation and vitamin D receptor polymorphisms on weight and body composition in overweight women with hypovitaminosis D: a randomized, double-blind, placebo-controlled clinical trial

Different responses to vitamin D supplementation may be due to genes involved in vitamin D metabolism, including the vitamin D receptor (VDR) gene. The present study aimed to determine the interactive effect of vitamin D supplementation and VDR polymorphisms, including FokI (rs2228570) and BsmI (1544410) on weight and body composition in overweight women with hypovitaminosis D. This study comprised two phases: a double-blind, randomized and a before-after clinical trial. In the first phase, 50 healthy overweight women aged 20-45 years with hypovitaminosis D were randomly categorized into intervention and control groups and were given 50 000 IU/w vitamin D3 or placebo for 12 weeks. In the second phase, 75 women received 50 000 IU/w of vitamin D3 for 12 weeks. All variables were measured at baseline and after 12 weeks. Circulating 25(OH)D was measured using an ELISA kit. Anthropometric indices were calculated according to standard protocol (WHO-TRH-854). Body composition was determined using the body impedance analysis method. The VDR polymorphisms were detected using the PCR sequence. Supplementation resulted in a significant increase in the level of 25(OH)D in the intervention group but did not affect the anthropometric profile of the subjects. When considering FokI genotypes, carriers of the FF genotype had higher fat mass reduction than carriers of Ff + ff genotypes.

Association of Serum 25(OH)D with Metabolic Syndrome in Chinese Women of Childbearing Age

Objective: To analyze the associations between serum 25(OH)D levels and the risk of metabolic syndrome (MetS) and its components, and the related genetic and non-genetic factors in non-diabetic women of childbearing age in China. Methods: Subjects were randomly selected from the 2015 Chinese Adult Chronic Disease and Nutrition Surveillance. The data of sociodemographic characteristics and lifestyle factors were obtained through questionnaire survey. Anthropometry was measured by trained interviewers, and fasting blood was collected to test 25-hydroxyvitamin D [25(OH)D], total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG), and other related parameters. Generalized linear mode and multivariate logistic analysis were performed to analyze the associations between serum 25(OH)D and MetS and its components, adjusting for the possible confounders. Results: Body mass index (BMI), serum alanine aminotransferase (ALT), hypersensitive C-reactive protein (hs-CRP), 25(OH)D, phosphorus (P), and parathyroid hormone (PTH) levels were associated with the number of MetS’s components. G allele carriers of GC rs2282679 had higher diastolic blood pressure (DBP) and FBG levels compared with the TT genotypes, while higher genetic risk score (GRS) seemed to be associated with reduced HDL-C level. The odds ratio (OR) for MetS in lowest group of 25(OH)D was 1.533 (0.980−2.399) after adjusting for season, district, area type, latitude, age, BMI, PTH, P, ALT, CRE, interleukin-6 (IL-6), and hs-CRP, compared with the median group, but the association was not significant. An insufficient 25(OH)D concentration (<14.22 ng/mL) was significantly related to the risk of elevated waist circumference (WC) (OR = 1.612 (1.014−2.561)) and TG (OR = 2.210 (1.318−3.706)), and reduced HDL-C (OR = 1.639 (1.206−2.229)) after adjusting for the confounders among these women. Moreover, these relationships were not affected by vitamin D metabolism-related gene polymorphisms. Conclusion: After comprehensively considering various influencing factors, significant associations between insufficient serum 25(OH)D and MetS‘s components, including elevated WC, TG, and reduced HDL-C, were observed. However, MetS, hypertension, and hyperglycemia were not found independently associated with 25(OH)D levels.

Vitamin D Supplementation and Genetic Polymorphisms Impact on Weight Loss Diet Outcomes in Caucasians: A Randomized Double-Blind Placebo-Controlled Clinical Study

Vitamin D deficiency or insufficiency is common in obese people, with some studies suggesting that low vitamin D level might be an independent predictor of obesity. Thus, the purpose of the present randomized, double-blind, placebo-controlled study was to investigate the effect of oral spray vitamin D₃ 3000 IU supplementation along with personalized weight-loss diet on obesity markers in overweight and obese Caucasians with vitamin d deficiency or insufficiency. The impact of vitamin D receptor (VDR) and adrenergic receptors (ADRs) genetic variants on vitamin D levels and weight loss diet outcomes was also investigated. After signing informed consent, a total of 125 eligible volunteers were randomly assigned into vitamin D (vitamin D₃ 3000 IU/d oral spray supplementation, n = 76) or placebo (xylitol, water, mint, n = 49) group following a weight loss program (600 calories less than the total energy expenditure of each volunteer) for 3 months. Fat mass, BMI, REE and 25(OH)D serum level were monitored on baseline and each month. DNA samples were extracted from buccal swabs and genotyped for the rs2228570 (VDR), rs1544410 (VDR), rs731236 (VDR), rs1800544 (ADRA2A), rs1801252 (ADRB1), rs1042713 (ADRB2), and rs4994 (ADRB3) polymorphisms. Statistical analysis was performed using SPSS package (v.23). Between group comparisons revealed significant improvement in serum 25(OH)D level and greater reduction in weight, BMI and fat percentage in the vitamin D group compared to placebo group (p < 0.05). In the vitamin D group, carriers of the rs2228570 T allele tended to have greater vitamin D level improvement compared with the homozygous C allele (p = 0.067). Furthermore, heterozygous (CT) for the rs731236 tended to have lesser weight loss (p = 0.068) and for the rs1042713, a lower decline in fat percentage was observed for homozygous AA carriers compared to the heterozygous (p = 0.051). In the control group, differences in weight loss (p = 0.055) and BMI (p = 0.045) were observed between rs1544410 AA and GG homozygous. In conclusion, vitamin D oral spray supplementation seems to improve vitamin D status and decrease obesity markers during a weight-loss intervention in overweight/obese Caucasians with vitamin D deficiency or insufficiency. Also, the results of the present study indicate that VDR and ADRs genetic polymorphisms seem to influence vitamin D supplementation response and obesity markers.

Relationship between the double burden of malnutrition and mental health in overweight and obese adult women

The co-existence of overweight or obesity with concurrent deficiency of one or more nutrients is referred to as double burden of malnutrition (DBM), and numerous mental health impairments have been associated with a variety of nutrient deficiencies. Although DBM is relevant for several health outcomes, the ubiquitous involvement of vitamin D across multiple systems and tissues suggests D insufficiency as a viable target for nutritional modification. The present study aimed to evaluate the contribution of DBM and mental health among adult women. Study participants included 300 women, aged 18–59 years, who presented to one of the 25 health centres in Tehran. Participants with a body mass index (BMI) of greater than 25 kg/m² and a plasma concentration of 25-hydroxy vitamin D [25(OH)D] of >20 ng/ml were considered to have DBM. The 147-item food frequency questionnaire was used to estimate their dietary intake. Mental health status was assessed using the depression, anxiety and stress scales-21 (DASS-21). The mean ± standard deviation age, weight and BMI of the participants were 36⋅49 ± 8⋅38, 80⋅89 ± 12⋅45 kg and 31⋅04 ± 4⋅31 kg/m², respectively. DBM was significantly associated with stress, after adjusting for potential confounders, including age, energy and marital status in model 1 (OR = 1⋅28, 95 % confidence interval (CI) 1⋅00, 1⋅65, P < 0⋅04) v. the crude model (OR = 1⋅22; 95 % CI 0⋅96, 1⋅55, P = 0⋅09). No significant association was seen among DBM and DASS-21 outcomes. In this cross-sectional study, stress and DBM were significantly associated. While vitamin D insufficiency was associated with mental health and obesity in opposing directions. Elucidation of whether vitamin D supplementation can improve mental health impairments requires further evaluation.

The Association Between FokI Vitamin D Receptor Polymorphisms With Metabolic Syndrome Among Pregnant Arab Women

Metabolic syndrome (MetS) is a serious health condition that is becoming extremely threatening in Saudi Arabia. The link between vitamin D receptor (VDR) gene polymorphisms and maternal MetS has been observed in several ethnic groups, but is yet to be clarified in the Arabian population. This study aims to investigate the relationship between the FokI VDR genotype and the risk of MetS and its components in pregnant Saudi women. A cross-sectional study was conducted using 368 pregnant Saudi women on first trimester screened for MetS (44 with MetS and 324 without MetS). Measurements included anthropometrics, glycemic and lipid profile and 25(OH)D. TaqMan genotyping assay was used to determine Fokl VDR genotype of participants. Vitamin D deficiency (25(OH)D <50nmol/l) was seen in 85% of the participants. An estimated 12% of participants had MetS. In the MetS group, the FokI VDR genotyping frequencies for FF, Ff, and ff genotypes were 50%, 36.4% and 13.6%, respectively. In controls, the frequencies were 62.7%, 31.4% and 5.9%, respectively. No significant association between the individual MetS components and FokI VDR genotypes were observed. Nevertheless, carriers of the ff allele had a significant risk for full maternal MetS [Odds Ratio 4.2 (95% Confidence Interval 1.4-12.2; adjusted p=0.009). The study suggests that the ff FokI VDR genotype is a genetic marker of maternal MetS in pregnant Arabian women. Prospective studies that include neonatal outcomes may confirm present findings.

Association of vitamin D receptor polymorphisms with metabolic syndrome-related components: A cross-sectional study

BACKGROUND

The association between vitamin D receptor (VDR) polymorphisms and metabolic syndrome (MS) has been demonstrated by epidemiological studies while their correlation remain controversial. The aim of this study is to investigate the association of VDR gene polymorphisms with MS and MS-related components in the two communities of Hangzhou.

METHODS

A total of 394 subjects were enrolled in the cross-sectional study. Four VDR gene polymorphisms (ApaI, BsmI, FokI, and TaqI) were selected based on human genome sequence databases and genotyped using the MassARRAY Analyzer Compact.

RESULTS

In lipid profile, the TT genotype of ApaI had a significantly lower risk of hypertriglyceridemia compared with the GG+GT genotypes (recessive model: OR = 0.141; 95% CI = 0.041-0.486; p < 0.01) and the GG genotype (codominant model: OR = 0.155; 95% CI = 0.044-0.545; p < 0.01). The levels of triglyceride (TG) in the TT genotype of ApaI were lower than the GG+GT genotypes (1.29 ± 0.63 vs. 1.78 ± 1.59 mmol/L, p < 0.01). Furthermore, the AA+GA carriers of BsmI had lower levels of high-density lipoprotein cholesterol (HDL-C) than the GG carriers (1.28 ± 0.29 vs. 1.42 ± 0.34 mmol/L, p < 0.05). The CC+TC carriers of TaqI also suffered from lower HDL-C compared with the TT carriers (1.27 ± 0.29 vs. 1.42 ± 0.34 mmol/L, p < 0.01). For arterial blood pressure, the CC carriers had lower systolic blood pressure (SBP) than the TT+TC carriers (p < 0.01) and the TT carriers of FokI (p < 0.05). However, the FokI polymorphisms were not associated with SBP and the mean blood pressure of both groups laid within the normal range.

CONCLUSIONS

In our study, VDR polymorphisms show no association with the MS risk. The present results suggest that the VDR ApaI polymorphism is associated with hypertriglyceridemia and predisposed to developing MS, while the variants of BsmI and TaqI seem to affect HDL-C. Nevertheless, the effect of FokI variants with SBP is ambiguous.

Association between Vitamin D Receptor Polymorphisms (BsmI and FokI) and Glycemic Control among Patients with Type 2 Diabetes

(1) Background: Several studies have suggested that the vitamin D receptor (VDR) gene plays a role in type 2 diabetes mellitus (T2DM) susceptibility. Nonetheless, the association between T2DM and VDR polymorphisms remains inconclusive. We determined the genotype of VDR rs1544410 (BsmI) and rs2228570 (FokI) polymorphisms among Malaysian patients with T2DM and their association with glycemic control factors (vitamin D levels, calcium, magnesium, and phosphate). (2) Methods: A total of 189 participants comprising 126 patients with T2DM (63 with good glycemic control and 63 with poor glycemic control) and 63 healthy controls were enrolled in this case-control study. All biochemical assays were measured using spectrophotometric analysis. VDR gene FokI and BsmI polymorphisms were analyzed using polymerase chain reaction and endonuclease digestion. (3) Results: Our findings revealed no significant differences in VDR FokI and BsmI genotypes between participants with T2DM and healthy controls. Moreover, no significant association was observed between both single nucleotide polymorphisms and glycemic control factors. Participants with poor glycemic control had significantly lower serum magnesium levels and significantly higher HOMA-IR compared to the other groups. (4) Conclusions: The present study revealed that VDR gene BsmI and FokI polymorphisms were not significantly associated with T2DM.

Is There a Feasible Link between Vitamin D Receptor Genotypic and Allelic Frequencies with Analytical Biomarkers of Rheumatoid Arthritis Disease?

Rheumatoid arthritis (RA) is one of the most widespread autoimmune disorders and it has a genetic background with a variety of genes affecting the degradation of the immune system. Along these lines, we assessed the relationship between the BsmI, and FokI VDR polymorphisms and inflammable records identified with infections activity. Such as interleukins (IL-6, IL-8), hypoxia inducible factor-alpha (HIF-α), soluble receptor of advanced glycation end product (sRAGE), oxidized low-density lipoprotein cholesterol (oxLDL), neutrophil gelatinase-associated lipocalin (NGAL) and procollagen N-propeptide of type III collagen (P3NP) and the allelic frequencies of BsmI VDR rs1544410 and FokI VDR rs2228570 polymorphism on the RA. Total of 131 subjects [70 RA patients and 61 age and sex matched apparently healthy controls (HC)] were monitored for inflammatory biomarkers using ELISA. All patients were screened for the BsmI and FokI using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The all biomarkers were significantly higher in RA patients in comparison with HC. There were positive correlations between NGAL, oxLDL and s-RAGE, oxLDL. On BsmI, 'GG' and 'AG' genotypes were significantly associated with high RA activity as well as the frequency of genotypes 'AG & GG" were higher in high activity RA as compared to low RA activity. However on FokI, was observed that in high activity patients the frequency of 'CC' & 'CT' was more prevalent as compared to low activity ones. These outcomes support the immunoregulatory role of vitamin D which is associated with several inflammatory diseases, signifying a credible anti-inflammatory role in perturbation of the RA.

Vitamin D receptor gene ApaI and FokI polymorphisms and its association with inflammation and oxidative stress in vitamin D sufficient Caucasian Spanish children

BACKGROUND

Vitamin D has gone from being just one vitamin to being an important prohormone with multiple effects on different tissue types. The mechanism of action of the active form or calcitriol is mediated by the intracellular vitamin D receptor (VDR). The interaction of the VDR with calcitriol modulates the expression of target genes involved in cell proliferation and cytokine production. Several studies have explored the effects of vitamin D deficiency in inflammatory disorders. Furthermore, some mutations in the VDR can affect its functionality. The focus of this study was to explore associations between VDR single nucleotide polymorphisms (SNPs) and markers of inflammation and oxidative stress in vitamin D sufficient children.

METHODS

This is a cross-sectional study of a Caucasian Spanish population including 155 healthy children (87 males, 68 females) aged 10 to 14 years. FokI, ApaI and TaqI SNPs of the VDR gene were genotyped. Routine biochemistry, serum levels of interleukin-6, tumor necrosis factor-α, interferon-γ, 8-isoprostaglandin F2α and nitrates were determined.

RESULTS

The homozygous major allele AA in the FokI SNP was associated with increased levels of high-density lipoprotein cholesterol in a recessive inheritance mode (P=0.025). The minor allele A of ApaI was significantly associated with decreased serum tumor necrosis factor-α and 8-isoprostaglandin F2α in an additive mode (P=0.016 and P=0.020 respectively). No significant associations were observed between the TaqI SNP and any of the parameters evaluated. Haplotype analysis confirmed the significance of the relationships between ApaI and FokI SNPs and parameters associated with inflammation and oxidative stress.

CONCLUSIONS

Genetic variations of VDR are associated with subtle changes in metabolic, inflammatory and oxidative stress markers. These results may provide a better understanding of the relationships between vitamin D and these clinical parameters.

Vitamin D pathway-related gene polymorphisms and their association with metabolic diseases: A literature review

PURPOSE

Given that the relationship between vitamin D status and metabolic diseases such as obesity and type 2 diabetes (T2D) remains unclear, this review will focus on the genetic associations, which are less prone to confounding, between vitamin D-related single nucleotide polymorphisms (SNPs) and metabolic diseases.

METHODS

A literature search of relevant articles was performed on PubMed up to December 2019. Those articles that had examined the association of vitamin D-related SNPs with obesity and/or T2D were included. Two reviewers independently evaluated the eligibility for the inclusion criteria and extracted the data. In total, 73 articles were included in this review.

RESULTS

There is a lack of research focusing on the association of vitamin D synthesis-related genes with obesity and T2D; however, the limited available research, although inconsistent, is suggestive of a protective effect on T2D risk. While there are several studies that investigated the vitamin D metabolism-related SNPs, the research focusing on vitamin D activation, catabolism and transport genes is limited. Studies on CYP27B1, CYP24A1 and GC genes demonstrated a lack of association with obesity and T2D in Europeans; however, significant associations with T2D were found in South Asians. VDR gene SNPs have been extensively researched; in particular, the focus has been mainly on BsmI (rs1544410), TaqI (rs731236), ApaI (rs7975232) and FokI (rs2228570) SNPs. Even though the association between VDR SNPs and metabolic diseases remain inconsistent, some positive associations showing potential effects on obesity and T2D in specific ethnic groups were identified.

CONCLUSIONS

Overall, this literature review suggests that ethnic-specific genetic associations are involved. Further research utilizing large studies is necessary to better understand these ethnic-specific genetic associations between vitamin D deficiency and metabolic diseases.

25-Hydroxy cholecalciferol, anti-Müllerian hormone, and thyroid profiles among infertile men

BACKGROUND AND AIM

We examined the relationship among vit.D₃, AMH, FT3, FT4, and TSH, in addition to the serum levels of reproductive hormones (FSH, LH, prolactin, and free testosterone), in oligoasthenoteratozoospermia and azoospermia patients in a cohort of infertile men from Egypt to establish a clinical marker/cause-effect relationship.

METHODS

This cross-sectional cohort study was carried out on 301 men (105 males with oligoasthenoteratozoospermia and 96 males with azoospermia), in addition to 100 controls. Measurements of serum vit.D₃, AMH, FT3, FT4, and TSH levels, in addition to reproductive hormone assays, were performed on all included subjects, using ELISA kits.

RESULTS

Overall, results showed significantly lower serum levels of vit.D₃ in infertile men than in the controls, with a greater decrease observed in men with azoospermia than in oligoasthenoteratozoospermia patients, (p < .05 for all). Significantly higher serum TSH and FSH levels and significantly lower serum free testosterone levels were observed in males with azoospermia than in males with oligoasthenoteratozoospermia and the controls (p < .05 for both). There were no significant differences between the studied groups in terms of AMH, FT3 or FT4 levels. LH levels were negatively correlated with TSH levels and positively correlated with AMH levels among men with oligoasthenoteratozoospermia, while among men with azoospermia, LH levels were positively correlated with vit.D₃ levels (p < .05 for all).

CONCLUSION

Decreased Vit.D₃ could play a role in male infertility, in addition to abnormal thyroid function, which needs further investigation.

Vitamin D Receptor Gene Polymorphisms and the Risk of Metabolic Syndrome (MetS): A Meta-Analysis

BACKGROUND

Several studies have assessed the association between the vitamin D receptor (VDR) polymorphism and the risk of metabolic syndrome (MetS). However, the results were inconsistent and inconclusive. Therefore, we conducted a meta-analysis to clarify the exact association between the vitamin D receptor (VDR) polymorphisms and the risk of MetS.

METHODS

All accessible studies reporting the association between the FokI (rs2228570) or/and TaqI (rs731236) or/and BsmI (rs1544410) or/and ApaI (rs7975232 polymorphisms of the Vitamin D Receptor and susceptibility to MetS published prior to February 2019 were systematically searched in Web of Science, Scopus, and PubMed. After that, Odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were estimated to evaluate the strength of the association in five genetic models.

RESULTS

A total of 9 articles based on four gene variations, and comprising 3348 participants with 1779 metabolic syndrome patients were included. The overall results suggested a significant association between BsmI (rs1544410) polymorphism and MetS susceptibility in recessive model (OR, 0.72, 95% CI, 0.55-0.95, fixed effect model), allelic model (OR, 0.83, 95% CI, 0.72-0.95, fixed effect model), and bb vs BB (OR, 0.65, 95% CI, 0.46-0.93, fixed effect). However, no significant association was identified between TaqI (rs731236) polymorphism, ApaI (rs7975232) polymorphism, and FokI (rs2228570) polymorphism and MetS.

CONCLUSION

This meta-analysis suggested an association between the BsmI (rs1544410) polymorphism and MetS. Indeed, BsmI (rs1544410) acts as a protective factor in the MetS. As a result, the VDR gene could be regarded as a promising pharmacological and physiological target in the prevention or treatment of the MetS.

Genetic variants of VDR and CYP2R1 affect BMI independently of serum vitamin D concentrations

BACKGROUND

Vitamin D metabolism and obesity have been linked by several studies, however the reason for this association is unclear. Our objective was to investigate potential correlations between genetic variants in key enzymes of vitamin D metabolism and the body mass index on a representative and random sample of Hungarian adults.

METHODS

Altogether 462 severely vitamin D deficient individuals were studied at the end of winter in order to decrease environmental and maximize any relevant genetic effect. Furthermore, participants with lifestyle factors known to affect vitamin D homeostasis were also excluded. We selected 23 target SNPs in five genes that encode key proteins of vitamin D metabolism (NADSYN1, GC, CYP24A1, CYP2R1, VDR).

RESULTS

Variants in 2 genetic polymorphisms; rs2853564 (VDR) and rs11023374 (CYP2R1) showed a significant association with participants' BMI. These associations survived further adjustment for total-, free-, or bioactive-25(OH) vitamin D levels, although the variance explained by these 2 SNPS in BMI heterogeneity was only 3.2%.

CONCLUSION

Our results show two novel examples of the relationship between genetics of vitamin D and BMI, highlighting the potential role of vitamin D hormone in the physiology of obesity.

Vitamin D receptor gene polymorphisms affecting changes in visceral fat, waist circumference and lipid profile in breast cancer survivors supplemented with vitamin D3

OBJECTIVE

We investigated whether vitamin D receptor (VDR) polymorphisms are associated with circulating metabolic biomarkers and anthropometric measures changes in breast cancer survivors supplemented with vitamin D3.

METHODS

One hundred sixty-eight breast cancer survivors admitted to Shohaday-e-Tajrish hospital received 4000 IU of daily vitamin D3 supplements for 12 weeks. Anthropometric measurements as well dietary, physical activity and plasma metabolic biomarkers assessments were performed before and after intervention. VDR polymorphisms were considered as the main exposures. Multivariate multiple linear regression analyses were used to determine the association between the VDR single-nucleotide polymorphisms (SNPs) and changes in metabolic and anthropometric measures in response to vitamin D3 supplementation.

RESULTS

One hundred twenty-five (85%) women had insufficient and inadequate levels of plasma 25-hydroxy vitamin D (25(OH)D) at baseline. Compared to the AA genotype of the ApaI, the aa category showed greater increase in muscle mass [71.3(10.7131.9)] and higher decrease in LDL-C [- 17.9(- 33.6, - 2.3)] levels after adjustment for potential confounders. In addition, the heterozygous genotype (Bb) of the BsmI VDR was associated with higher increase in WC following vitamin D3 supplementation, compared to BB [2.7(0.1,5.3)]. Haplotype score analyses indicate a significant association between inferred haplotypes from BsmI, ApaI, TaqI and FokI, BsmI and Cdx2 VDR polymorphisms and on-study visceral fat changes.

CONCLUSIONS

Findings of this study showed that genetic variation in the VDR gene was associated with changes in cardio-metabolic parameters in breast cancer survivors, supplemented with vitamin D3, results could provide a novel insight into better understanding of which subset of individuals benefit most from normalization of vitamin D status.

TRIAL REGISTRATION

This trial has been registered on the Iranian Registry of Clinical Trials (IRCT) under the identification code: IRCT2017091736244N1, registration date: 2017-11-10, http://www.irct.ir/trial/27153 and was approved by the ethics committees of the National Nutrition and Food Technology Research Institute (NNFTRI), Shahid Beheshti University of Medical Sciences (SBMU).

Association of Vitamin D receptor gene BsmI polymorphism with type 2 diabetes mellitus in Pakistani population

Background

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder with strong genetic components. The reported association of vitamin D receptor (VDR) gene polymorphisms varies among ethnic groups.

Objectives

The present study was conducted to determine association of vitamin D receptor gene BsmI (rs1544410 A>G) polymorphism with type 2 diabetes mellitus in Pakistani population.

Methods

Blood samples were collected from 150 T2DM patients and 100 non-diabetic engaged by convenient sampling method. After collection of demographic data, assessment of fasting glucose (FG), vitamin D, HbA1c, renal function tests, liver function tests and lipid profile was done. Candidate gene polymorphism was analyzed by DNA amplification with polymerase chain reaction and endonuclease digestion.

Results

Biochemical parameters were significantly different among case and control groups. Associations of BsmI genotype with T2DM, related complications and biochemical variables were not significant.

Conclusion

The current study did not provide evidence for the association of VDR gene BsmI polymorphism with T2DM in Pakistani population.

Vitamin D receptor gene polymorphisms are associated with triceps skin fold thickness and body fat percentage but not with body mass index or waist circumference in Han Chinese

Background

Evidence shows that low serum vitamin D concentrations account for an increased risk of obesity by inducing vitamin D receptor (VDR) hypofunction. Although the correlation between single nucleotide polymorphisms (SNPs) of VDR gene and obesity-related anthropometric measures (such as body mass index [BMI] and waist circumference[WC]) has already been tested, there are only few studies on the association between direct measures of body fat percentage (BFP) and triceps skinfold thickness and the SNPs of VDR. The aim of the present study was to evaluate the effect of VDR gene polymorphism on multiple obesity indexes in Han Chinese, including BMI, WC, BFP and triceps skinfold thickness.

Methods

In this cross-sectional study, five hundred and seventeen healthy Chinese adults were enrolled in the trial. Four loci in VDR gene (rs2228570 [FokI], rs2189480, rs2239179 and rs7975232[ApaI]) were genotyped by TaqMan probe assays. Obesity indexes including BMI, WC, BFP and triceps skinfold thickness were used to evaluate the relationship to the VDR SNPs. Multiple logistic regression, linear regression and general multifactor dimensionality reduction (GMDR) were performed to analyze the correlation of VDR gene and obesity indexes.

Results

None of the VDR SNPs were associated with BMI and WC, the C allele of FokI and the T allele of ApaI were associated with an increase in BFP (β = 0.069,P = 0.007; β = 0.087, P = 0.022 respectively); the G allele of rs2239179 and the T allele of ApaI were associated with an increase in triceps skin fold thickness (β = 0.074, P = 0.001; β = 0.122, P < 0.001 respectively). In regards to adiposity-related metabolic parameters, we found that the GT genotype of ApaI was associated with higher level of total cholesterol (TC) (P = 0.013) and Low-density lipoprotein cholesterol (LDL-C) (P = 0.001).

Conclusions

Though we failed to prove that VDR SNPs were in correlation with BMI and WC, we did establish the association between VDR variants and BFP, as well as triceps skinfold thickness. Data obtained suggested that the VDR variants play an important role in regulating adipose tissue activity and adiposity among Han Chinese.

Electronic supplementary material

The online version of this article (10.1186/s12944-019-1027-2) contains supplementary material, which is available to authorized users.

Vitamin D receptor gene polymorphisms and 25(OH) vitamin D: Lack of association to glycemic control and metabolic parameters in type 2 diabetic Egyptian patients

BACKGROUND

Vitamin D deficiency and vitamin D receptor (VDR) gene polymorphisms have been linked to type 2 diabetes mellitus (T2DM) and its metabolic parameters, however there are conflicting results therefore we aimed to evaluate VDR gene polymorphisms (Fok1, Bsm1 and Taq1) and vitamin D status in Egyptian patients with T2DM and to detect the associations of these polymorphisms to their metabolic parameters and glycemic control.

METHODS

50 patients with T2DM and 50 healthy age matched control subjects were enrolled. FBG, 2 h -PPG, fasting lipids, Hb A1c, calcium, phosphorus, urea, creatinine, ALT, AST were measured. BMI has calculated. Serum 25 hydroxy vitamin D [25(OH)D] has measured by ELISA. VDR gene polymorphisms detection has done by polymerase chain reaction through restriction fragment length polymorphism (PCR-RFLP) technique.

RESULTS

Our study has shown lower mean levels of 25(OH)D in patients with T2DM (28.54 ± 10.02) in comparison with control subjects (44.65 ± 7.19), p < 0.001. Vitamin D insufficiency was more prevalent in T2DM 58% than in healthy control subjects 4%. There were statistically significant differences between patients with type 2 diabetes and controls regarding the distribution of FokI genotypes and alleles (p = 0.005) and non significant difference regarding Bsm1 and Taq1. Neither VDR gene polymorphisms nor 25(OH)D showed significant association with glycemic control, fasting lipids and BMI in patients with T2DM.

CONCLUSIONS

Vitamin D deficiency is prevalent in Egyptian patients with T2DM. Associations were found only between VDR FokI gene polymorphism and susceptibility to Egyptian patients with T2DM. Non significant differences in VDR gene polymorphisms distribution has found regarding glycemic control and metabolic parameters.

Associations of Serum 25-Hydroxyvitamin D with Physical Performance and Bone Health in Overweight and Obese Older Adults

Low vitamin D status commonly accompanies obesity, and both vitamin D deficiency and obesity have been associated with falls and fracture risk in older adults. We aimed to determine the associations of serum 25-hydroxyvitamin D (25(OH)D) concentrations with physical performance and bone health in community-dwelling, overweight and obese older men and women. Serum 25(OH)D concentrations were measured in 84 participants with body mass index ≥25 kg/m² (mean ± SD age 62.4 ± 7.9 years; 55% women). Physical function was determined by short physical performance battery, hand grip and quadriceps strength, and stair climb power tests. Body composition and bone structure were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, respectively. Mean ± SD 25(OH)D was 49.6 ± 17.7 nmol/L, and 50% of participants had low 25(OH)D (<50 nmol/L) levels. 25(OH)D concentrations were positively associated with quadricep strength and stair climb power in women (B = 0.15; 95% CI 0.02–0.27 kg and B = 1.07; 95% CI 0.12–2.03 W, respectively) but not in men. There were no associations between 25(OH)D and bone parameters in either sex after multivariable adjustment (all p > 0.05). Lower 25(OH)D concentrations are associated with poorer quadricep strength and muscle power in overweight and obese older women but not men.

The association of VDR polymorphisms and type 2 diabetes in older people living in community in Santiago de Chile

INTRODUCTION

Several polymorphisms have been associated with obesity and type 2 diabetes in different populations.

OBJECTIVE

To investigate the frequencies of a genetic polymorphism of vitamin D receptor (FokI and BsmI) in patients with T2D.

METHODS

The case-control study was conducted in 138 patients with T2D and 172 control subjects, men and women (60-79 years old). The genotype and allele frequency determination of VDR polymorphisms were determined in these subjects.

RESULTS

The frequency of the C allele of the FokI polymorphism was significantly higher in the T2D group than in healthy subjects (p = 0.025). The frequencies of the BsmI variant were similar in subjects with and without T2D (p = 0.747). Consistent with these data, there was an association of the C allele with T2D (OR = 1.74, 95% CI = 1.003-3.084, p = 0.036), but not the AG + GG variants for BsmI (OR = 1.02, 95% CI = 0.635-1.649, p = 0.916). We can observe a significant association between carrier of the T > C variant of FokI and type 2 diabetes, adjusted for vitamin D, age, obesity (overweight and obesity), seasonality, sex and Homa-IR. Here, we show a significant association between the FokI polymorphisms (TC + CC) and T2D with an odds ratio of 1.9001 (95% CI (1.0970-3.6838), p = 0.041).

CONCLUSION

Our study suggests that the C allele (TC + CC) of the VDR-FokI gene is a possible risk factor for T2D in older people living in a community in Santiago de Chile.

Vitamin D Metabolism-Related Gene Haplotypes and Their Association with Metabolic Disturbances Among African-American Urban Adults

Epidemiological studies have confirmed associations of the vitamin D receptor (VDR) and vitamin D-related gene polymorphisms with adiposity and other metabolic disturbances. Those associations may be sex-specific. We evaluated the cross-sectional and longitudinal relationships between metabolic disturbances and haplotypes constructed from single nucleotide polymorphisms of VDR (BsmI:G/A: rs1544410; ApaI:A/C: rs7975232; and TaqI:G/A: rs731236) and MEGALIN (rs3755166:G/A; rs2075252:C/T and rs2228171:C/T) genes, in a sample of African-American adults. From 1,024 African Americans participating in the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS, 2004–2013, Baltimore, MD), our analyses included 539 participants with complete genetic, baseline covariate and metabolic outcome data (at baseline and follow-up). Mean ± SD period of follow-up was 4.64 ± 0.93 y. Multivariable-adjusted Cox proportional hazards and logistic regression models were conducted. Among key findings, in men, incident hypertension was inversely related to MEGALIN₁ (GCC), [HR = 0.45, 95% CI: 0.23–0.90, p = 0.024]. Overall, there was a direct, linear dose-response association between VDR₂ (AAG: BAt) and MetS at baseline [OR = 1.60, 95% CI: 1.11–2.31, p = 0.012], while among men, VDR₃ (GAA: bAT) was inversely related to baseline MetS [OR = 0.40, 95% CI: 0.19–0.81, p = 0.011]. In conclusion, VDR and MEGALIN gene variations can affect prevalent MetS and the incidence rate of hypertension, respectively, among African-American urban adults.

Association of vitamin D receptor gene polymorphisms with serum 25(OH)D levels and metabolic syndrome in Thai population

Metabolic syndrome (MetS) increases the risk of developing cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). The vitamin D receptor gene (VDR) polymorphisms have been found associated with MetS and serum 25(OH)D levels but these associations remain controversial. The aim of this study was to investigate the relationship between the VDR polymorphisms and MetS, metabolic components, and serum 25(OH)D levels within the Thai population. A case-control study included 237 participants with MetS according to the MetS diagnostic criteria of NCEP ATPIII and 376 controls. Anthropometric data, blood pressure, lipid profiles, serum 25 (OH)D, and fasting blood glucose were measured. VDR FokI, BsmI, TaqI, and Cdx2 polymorphisms were genotyped by using PCR-HRM. There were no significant differences in the frequencies of VDR genotypes and alleles between MetS and the control groups. VDR TaqI TT, and BsmI BB + Bb genotypes were associated with lower 25(OH)D levels (p < 0.05) in comparison to TaqI Tt, and BsmI bb genotypes in the MetS group, respectively. In addition, the VDR Cdx2 GG genotype was associated with higher WC compared with the AG genotype in all subjects (p < 0.05). Logistic regression analysis revealed that BB + Bb genotypes of the VDR BsmI had significantly increased the odds ratio (OR) of hypertriglyceridemia when compared with the bb genotype (OR 1.87; 95% CI 1.10-3.19, p = 0.022). In conclusion, VDR BsmI variant was associated with hypertriglyceridemia and may be predisposed to developing MetS. VDR TaqI and BsmI polymorphisms seems to influence serum 25(OH)D levels in MetS subjects, while Cdx2 polymorphism may influence WC in all subjects.

Prevalence Pattern of Key Polymorphisms in the Vitamin D Receptor gene among Patients of Type 2 Diabetes Mellitus in Northeast India

AIMS

To investigate the association between Vitamin D receptor gene polymorphisms (BsmI, TaqI and FokI) and type 2 diabetes mellitus in patients in north eastern India.

SETTINGS AND DESIGN

This was a case control study with 40 cases of type 2 diabetes and 20 controls.

MATERIALS AND METHODS

Genomic DNA was extracted from blood and genotyped for the single nucleotide polymorphism (SNPs) of BsmI [rs1544410], TaqI [rs731236] and FokI [rs2228570] by polymerase chain reaction and gene sequencing. Genotype distribution and allelic frequencies were compared between patients and controls. Data was expressed as mean ±standard deviation. Chi square test and t test were used to compare groups. Statistical analysis was done using SAS version 9.3 software. P value of <0.05 was considered significant.

RESULTS

Body weight and BMI were significantly associated with VDR polymorphisms BsmI and TaqI while BsmI was significantly associated with HbA1C. Vitamin D deficiency was significantly greater in cases than controls. The frequency of the heterozygous genotype of the BsmI polymorphism was significantly greater in type 2 diabetics than in controls.

CONCLUSIONS

Vitamin D receptor polymorphisms are associated with type 2 diabetes in our population and require larger scale studies to be considered as possible risk factors or type 2 diabetes mellitus.

Establishing a genetic link between FTO and VDR gene polymorphisms and obesity in the Emirati population

Background

Obesity is a metabolic disease that is widely prevalent with approximately 600 million people classified as obese worldwide. Its etiology is multifactorial and involves a complex interplay between genes and the environment. Over the past few decades, obesity rates among the Emirati population have been increasing. The aim of this study was to investigate the association of candidate gene single nucleotide polymorphisms (SNPs), namely FTO (rs9939609) and VDR (rs1544410), with obesity in the UAE population.

Methods

This is a case-control study in which genomic DNA was extracted from saliva samples of 201 obese, 115 overweight, and 98 normal subjects in the United Arab Emirates (UAE). Genotyping for the variants was performed using TaqMan assay.

Results

The mean Body Mass Index (BMI) ± SD for the obese, overweight, and normal subjects was 35.76 ± 4.54, 27.53 ± 1.45, and 22.69 ± 1.84 kg/m², respectively. Increasing BMI values were associated with increase in values of HbA1c, systolic and diastolic blood pressure. There was a significant association observed between the FTO SNP rs9939609 and BMI (p = 0.028), with the minor allele A having a clear additive effect on BMI values. There was no significant association detected between BMI and rs1544410 of VDR. Moreover, significant interaction between the FTO rs9939609 and physical activity reduced the “AA” genotype effect on increase in BMI (p = 0.027).

Conclusions

Our study findings indicate that the minor allele A of the rs9939609 has a significant association with increasing BMI values. Moreover, our findings support the fact that increasing BMI is associated with increasing risks of other comorbidities such as higher blood pressure, poorer glycemic control, and higher triglycerides. In addition, physical activity was found to attenuate the effect of the “AA” genotype on the predisposition to higher BMI values.

Vitamin D receptor gene polymorphisms among Emirati patients with type 2 diabetes mellitus

At a prevalence rate close to 19.5%, the UAE has one of the highest rates of Type 2 Diabetes Mellitus (T2DM) in the world. Genome wide association studies (GWAS) have led to the identification of several genetic variants that are associated with T2DM. Recently, genes involved in vitamin D metabolism have gained interest because of the association between vitamin D deficiency (VDD) and increased risk for T2DM. Among these, the Vitamin D receptor (VDR) gene is a good candidate for T2DM susceptibility. The aim of this study was to investigate the association between VDR polymorphisms and T2DM among a representative sample of the Emirati population. In this cross sectional study, two hundred and sixty four patients with T2DM and ninety-one healthy controls were enrolled. The study population was genotyped for the three VDR gene mutations, TaqI (rs731236), FokI (rs2228570) and BsmI (rs1544410). VDR alleles and haplotypes were compared between patients and their healthy controls. The mean age of the T2DM cohort was 60±11.59years and 48.21±12.17years for the healthy controls. The G-allele and GG genotype of rs2228570 and T-allele and TT genotype of rs1544410 SNPs were associated with T2DM. In regards to T2DM-related metabolic complications, the AG and GG genotypes of rs731236 were significantly associated with higher total cholesterol (p=0.011) and LDL-cholesterol (p=0.009) levels in the patients with T2DM. In contrast, the CT genotype of rs1544410 was significantly associated with lower BMI (p=0.031) and the TT genotype was associated with lower LDL-cholesterol level (p=0.007). The frequency of AAT and GGC haplotypes was also different between groups (p=0.014; p=0.032, respectively), implying that these haplotypes of the VDR gene are associated with the susceptibility to T2DM in the Emirati population. To conclude, an association between SNPs in the VDR gene (except for rs731236) and T2DM per se was demonstrated. The rs731236 variant was shown to be associated with high cholesterol and LDL-cholesterol levels in T2DM patients, while rs1544410 was associated with lower BMI and lower LDL cholesterol levels. Our results imply that alleles and haploypes of the VDR gene are associated with the susceptibility to T2DM in the Emirati population.

Relationship Between Vitamin D Status and Vitamin D Receptor Gene Polymorphisms With Markers of Metabolic Syndrome Among Adults

Introduction: Recent studies have demonstrated that vitamin D deficiency contributes to the development of metabolic disorders, including obesity and type 2 diabetes mellitus (T2DM). Several vitamin D receptor (VDR) gene polymorphisms had been described to play a role in these conditions since vitamin D receptors were found in many tissues. The aim of this study was to assess the relationship between vitamin D status and VDR gene polymorphisms with metabolic syndrome (MS) parameters in Russian middle-aged women. Materials and Methods: A total of 697 women aged between 30 to 55 years were included in this cross-sectional study. Serum 25-hydroxyvitamin D (25(OH)D) level and four VDR gene polymorphisms rs1544410 (BsmI), rs7975232 (ApaI), rs731236 (TaqI), and rs2228570 (FokI) were measured. We applied the International Diabetes Federation (IDF) criteria to identify subjects with MS. Results: 9.3% of subjects had normal vitamin D level, while 90.7% were insufficient or deficient. Abdominal obesity (AO) was seen in 75.5%, impaired glucose tolerance (IGT) or T2DM was observed in 33.3%, reduced high-density lipoprotein cholesterol (HDL-C) level in 32.2% and hypertriglyceridemia in 23.4%. Serum 25(OH)D level in women with or without MS did not differ (48.6 ± 1.8 and 51.1 ± 1.5 nmol/l, p > 0.05). Subjects with vitamin D deficiency showed an increased risk of AO [CI 95% 2.23; 1.15-4.30] and low HDL-C [CI95% 2.60; 1.04-6.49] compared to subjects with normal 25(OH)D level. IGT and T2DM risk was increased only when 25(OH)D concentration was less than 39.0 nmol/l [CI 95% 7.17; 2.99-17.7], but risk of MS did not differ in normal vitamin D status subjects and insufficient/deficient ones (p > 0.05). T allele carriers (A) of rs7975232 had higher total cholesterol and low-density lipoprotein cholesterol levels compared with the GG (aa) genotypes. Similarly, GG (BB) genotype carriers of rs1544410 had higher triglyceride levels than subjects with A (b) allele carriers. However VDR gene polymorphisms did not seem to be associated with an increased risk of MS. Conclusions: Vitamin D deficiency, rs7975232, and rs1544410 VDR gene variants are associated with MS parameters in Russian middle-aged women.

Association of Vitamin D receptor gene polymorphisms with metabolic syndrome and its components among adult Arabs from the United Arab Emirates

AIMS

The aim was to investigate relationships of Vitamin D receptor gene (VDR) polymorphisms to the components of MetS among Arabs adult residing in the United Arab Emirates.

METHODS

A cross-sectional study of 198 Arabs adult (50 males and 148 females). Serum levels of glucose, vitamin D, HDL-C, and TG, and blood pressure were measured. FokI, BsmI & TaqI genotyping of VDR were investigated using PCR-RFLP technique.

RESULTS

Age of the participants was 21(9) years with a BMI of 26.8(7.8) kg/m². About 15% had MetS with serum vitamin D levels of 25.5(18.2) nmol/L. VDR genotyping yielded: FokI: 57.1% FF and 38.9% Ff, BsmI: 29.8% bb and 51.5% Bb, while TaqI showed 39.4% TT and 43.4% Tt. The ff carriers had higher total cholesterol [174(12.4) mg/dl] than FF and Ff genotypes. Bb carriers showed higher BMI and LDL-C than BB and bb genotypes. In females, FokI VDR polymorphism showed significant association with systolic blood pressure (SBP) and F allele carriers were at higher risk of developing high SBP [x²=4.4, df1, OR=0.29 (95%CI: 0.087-0.98), p=0.035].

CONCLUSION

VDR gene polymorphisms were not associated with MetS, yet it may affect the severity of some of components of MetS, namely the association of BsmI with obesity, FokI and BsmI with dyslipidemia and FokI with SBP.

The vitamin D receptor functional variant rs2228570 (C>T) does not associate with type 2 diabetes mellitus

AIM

Vitamin D acts through the binding to the vitamin D receptor (VDR). Several polymorphisms in VDR gene have been studied. Among these, the rs2228570 C>T (FokI) variant has been demonstrated to be functional, leading to a protein with a different size and activity. So far, genetic studies on the association between VDR gene rs2228570 single nucleotide polymorphism (SNP) and type 2 diabetes mellitus (T2DM) showed contradictory results. Thus, we performed an association study in a large cohort of adult Italian subjects with T2DM and in nondiabetic controls.

MATERIALS AND METHODS

For this study, 1713 subjects, 883 T2DM patients and 830 controls, were genotyped for the polymorphism. All participants without a diagnosis of diabetes underwent oral glucose tolerance test (OGTT), with measurement of glucose and insulin levels. Indices of insulin resistance (Homeostatic model assessment of insulin resistance, insulin sensitivity index), secretion (homeostatic model assessment for beta-cell, corrected insulin response at 30 minutes) and disposition index were calculated.

RESULTS

Genotype distributions and allele frequencies did not show difference between T2DM subjects and controls. We did not find significant differences among the three genotypes regarding gender, age, BMI, waist, hip, waist-to-hip ratio, and blood pressure. There were also no significant differences in lipid parameters, aspartate aminotransferase, and alanine aminotransferase levels. We tested for association with OGTT-derived data and surrogate indices of insulin resistance and secretion. We did not find significant differences among the genotypes in any of above-mentioned parameters. Furthermore, vitamin D levels were measured in a subgroup of subjects. We did not find significant differences among the genotypes.

CONCLUSIONS

Our study does not provide evidence for the association of the rs2228570 polymorphism with T2DM in a Caucasian population.

Genetic association analysis of vitamin D receptor gene polymorphisms and obesity-related phenotypes

Vitamin D has been established as a key factor in the development of obesity through the vitamin D receptor (VDR). The aim of this study was to investigate the contribution of the VDR gene to obesity-related phenotypes in a population of Caucasian young adults. The study population consisted of 701 healthy Spanish young adults (mean age 20.41±2.48). Three single-nucleotide polymorphisms (SNPs) of VDR (TaqI, BsmI and FokI) were selected as genetic markers. Body composition measurements including weight, body mass index (BMI), fat mass (FM), percentage of fat mass (PFM), fat-free mass (FFM) and visceral fat level (VFL) were analysed. Differences in obesity traits across the genotypes were determined using analysis of covariance (ANCOVA). The FokI polymorphism showed a significant association with PFM across the whole population after adjusting for age and sex (p=0.022). Age-adjusted analysis revealed an association between body weight and the TaqI and BsmI SNPs in males (p=0.033 and p=0.028, respectively). However, these positive findings did not remain significant after applying the Bonferroni correction for multiple testing. Our findings suggest that VDR genetic variants are unlikely to play a major role in obesity-related phenotypes in a population of Caucasian young adults.

Association of vitamin D receptor gene polymorphisms with diabetic dyslipidemia in the elderly male population in North China

Background

The prevalence of dyslipidemia is rising alarmingly in elderly Han Chinese male patients with type 2 diabetes mellitus (T2DM). The genetic factors that contribute to the development of diabetic dyslipidemia remain incompletely identified. This study was conducted to assess the association between vitamin D receptor (VDR) polymorphisms and development of dyslipidemia in the Han elderly male population with T2DM in North China.

Methods

A total of 242 T2DM patients with dyslipidemia (DH group, n=108) or without dyslipidemia (DO group, n=134) and 100 controls were genotyped for ApaI, TaqI and FokI single nucleotide polymorphisms (SNPs) of the VDR gene using polymerase chain reaction-restriction fragment length polymorphism and sequencing. The frequency and distribution of the SNPs were compared between cases and controls.

Results

The distribution of genotypes of VDR-FokI was significantly different between the control and DM group (P=0.033), as well as between the control and DH subgroup (P=0.011) but not DO subgroup (P=0.111). The frequency of C allele and CC genotype of FokI was significantly higher in the DH patients than in the controls (P=0.015 and P=0.003, respectively). Logistic regression analysis in a dominant model homozygous for the C allele of the FokI SNP showed that CC genotype was associated with DH patients (OR =1.797, 95% CI: 1.077–2.999, P=0.025). Significant associations of the ApaI and TaqI SNPs with either DO or DH subjects were not observed.

Conclusion

These findings suggest that CC genotype of VDR-FokI is a risk factor for T2DM patients with dyslipidemia in elderly males in North China.

Association of Sun Exposure, Skin Colour and Body Mass Index with Vitamin D Status in Individuals Who Are Morbidly Obese

Vitamin D deficiency is a common issue, particularly in obese populations, and is tested by assessing serum 25(OH)D concentrations. This study aimed to identify factors that contribute to the vitamin D status in fifty morbidly obese individuals recruited prior to bariatric surgery. Data collected included serum 25(OH)D concentrations, dietary and supplement intake of vitamin D, sun exposure measures, skin colour via spectrophotometry, and genotype analysis of several single nucleotide polymorphisms in the vitamin D metabolism pathway. Results showed a significant correlation between serum 25(OH)D concentrations and age, and serum 25(OH)D and ITAC score (natural skin colour). Natural skin colour accounted for 13.5% of variation in serum 25(OH)D, with every 10° increase in ITAC score (i.e., lighter skin) leading to a 9 nmol/L decrease in serum 25(OH)D. Multiple linear regression using age, ITAC score, and average UV index in the three months prior to testing, significantly predicted serum 25(OH)D concentrations (R² = 29.7%). Single nucleotide polymorphisms for all vitamin D genes tested, showed lower serum 25(OH)D for those with the rare genotype compared to the common genotype; this was most pronounced for fok1 and rs4588, where those with the rare genotype were insufficient (<50 nmol/L), and those with the common genotype were sufficient (≥50 nmol/L). Assessing vitamin D status in individuals with morbid obesity requires testing of 25(OH)D, but potential risk factors for this population include natural skin colour and age.

Vitamin D metabolism in human adipose tissue: could it explain low vitamin D status in obesity?

Obesity and a low vitamin D (VD) status, as well as a positive association between them, are prevalent worldwide. Additionally, a low VD status has been positively correlated with metabolic dysfunction (although not so convincingly as for obesity). The VD receptor (VDR) mediates VD biological actions in adipose tissue (AT), where VD can be activated or inactivated/degraded through specific hydroxylation steps. Additionally, AT can also store and release VD when needed. A lower VD activation/VD inactivation ratio and an impaired VDR signaling in AT could contribute to metabolic dysfunction besides the aforementioned association between obesity and VD status. However, subcutaneous (SAT) and visceral AT (VAT) are not expected to be similarly accountable as these two fat depots play differential roles in metabolic regulation/dysfunction. To our knowledge, only three articles disclose the evaluation of the expression of VDR and/or VD hydroxylating enzymes in human SAT and VAT. A clear dependence on the subcutaneous and/or the visceral fat depot is missing for the relationships of a) obesity and/or metabolic dysfunction with VD status and b) adipose VDR signaling and adipose VD activation/VD inactivation ratio with VD status, obesity and/or metabolic dysfunction. Further studies are warranted to unravel the influence of adipose VD metabolism on VD status.

Association of vitamin D receptor gene polymorphism (VDR) with vitamin D deficiency, metabolic and inflammatory markers in Egyptian obese women

Vitamin D deficiency might contribute to the pathogenesis of metabolic syndrome and could cause immune disturbance. The aim of this study is to analyze the associations between Vitamin D receptor (VDR) gene polymorphism, serum 25-hydroxy vitamin D, metabolic and inflammatory biomarkers in Egyptian obese women. The study included 201 obese women with vitamin D deficiency and 249 obese matched age healthy controls with sufficient vitamin D levels. Their age ranged between 25 and 35 years. Inflammatory biomarkers (interleukin-6 and C-reactive protein) and serum 25(OH) D were measured by enzyme-linked immunosorbent assay. Insulin resistance (IR) was determined by the homeostasis model assessment of insulin resistance (HOMA-IR).Vitamin D receptor (VDR) gene polymorphisms of FokI, ApaI, and TaqI were studied by PCR using the restriction fragment length polymorphism (RFLP) technique. Obese women with vitamin D deficiency had significant higher values of inflammatory and metabolic parameters compared to controls. Multivariable-logistic regression showed associations between 25(OH) D deficiency and metabolic components when comparing cases with controls. Moreover, cases carrying polymorphic alleles showed significant lower levels of serum 25(OH) D and higher HOMA-IR, blood pressure levels and lipid parameters compared to those with the wild type homozygote in obese cases with vitamin D deficiency. Vitamin D deficiency in Egyptian obese women with vitamin D deficiency is associated with abnormal metabolic components and abnormal inflammatory biomarkers. Moreover, VDR polymorphisms play important role in immune and inflammation status.

The associations between VDR BsmI polymorphisms and risk of vitamin D deficiency, obesity and insulin resistance in adolescents residing in a tropical country

Background

The vitamin D receptor (VDR) gene is expressed abundantly in different tissues; including adipocytes and pancreatic beta cells. The rs1544410 or BsmI single nucleotide polymorphism (SNP) in the intronic region of the VDR gene has been previously associated with vitamin D levels, obesity and insulin resistance.

Aims

This study was aimed to examine the association between BsmI polymorphism and risk of vitamin D deficiency, obesity and insulin resistance in adolescents living in a tropical country.

Methods

Thirteen-year-old adolescents were recruited via multistage sampling from twenty-three randomly selected schools across the city of Kuala Lumpur, Malaysia (n = 941). Anthropometric measurements were obtained. Obesity was defined as body mass index higher than the 95^th percentile of the WHO chart. Levels of fasting serum vitamin D (25-hydroxyvitamin D (25(OH)D)), glucose and insulin were measured. HOMA-IR was calculated as an indicator for insulin resistance. Genotyping was performed using the Sequenom MassARRAY platform (n = 807). The associations between BsmI and vitamin D, anthropometric parameters and HOMA-IR were examined using analysis of covariance and logistic regression.

Result

Those with AA genotype of BsmI had significantly lower levels of 25(OH)D (p = 0.001) compared to other genotypes. No significant differences was found across genotypes for obesity parameters. The AA genotype was associated with higher risk of vitamin D deficiency (p = 0.03) and insulin resistance (p = 0.03) compared to GG. The A allele was significantly associated with increased risk of vitamin D deficiency compared to G allele (adjusted odds ratio (OR) = 1.63 (95% Confidence Interval (CI) 1.03–2.59, p = 0.04). In those with concurrent vitamin D deficiency, having an A allele significantly increased their risk of having insulin resistance compared to G allele (adjusted OR = 2.66 (95% CI 1.36–5.19, p = 0.004).

Conclusion

VDR BsmI polymorphism was significantly associated with vitamin D deficiency and insulin resistance, but not with obesity in this population.

Assessment of the environmental and genetic factors influencing prevalence of metabolic syndrome in Saudi Arabia

Metabolic syndrome (MS) is a combination of factors that increases the risk of cardiovascular atherosclerotic diseases including diabetes, obesity, dyslipidemia, and high blood pressure. Cardiovascular diseases are one of the leading causes of death in the adult Saudi population where the increase in cardiovascular-related mortality is augmented by the rise in the prevalence of MS. Metabolic syndrome is a multi-factorial disorder influenced by interactions between genetic and environmental components. This review aims to provide a comprehensive assessment of studied environmental and genetic factors explaining the prevalence of MS in the Kingdom of Saudi Arabia. Additionally, this review aims to illustrate factors related to the population genetics of Saudi Arabia, which might explain a proportion of the prevalence of MS.

Relationship between vitamin D receptor gene polymorphisms, cardiovascular risk factors and adiponectin in a healthy young population

AIM

To explore the association between VDR polymorphisms and several cardiovascular risk factors and adiponectin.

MATERIALS & METHODS

Three-hundred and sixty-nine healthy students were randomly selected. Five VDR polymorphisms were genotyped: BsmI rs1544410; Cdx2 rs11568820; ApaI rs7975232; TaqI rs731236 and FokI rs2228570. BMI, waist circumference (WC), blood pressure, lipid/glycemic profiles and adiponectin were assessed.

RESULTS

In men, BsmI, ApaI and TaqI were associated with BMI and WC (p < 0.05). FokI was associated with triglycerides and high-density lipoprotein levels (p = 0.0036; p = 0.005) whereas BsmI and Cdx2 were associated with adiponectin levels (p = 0.026; p = 0.048). Associations disappeared after BMI and WC adjustments. In women, ApaI was associated with systolic blood pressure (p = 0.02).

CONCLUSION

Our study demonstrated a gender-specific difference between VDR SNPs and various cardiovascular risk factors and adiponectin.

A vitamin D pathway gene-gene interaction affects low-density lipoprotein cholesterol levels

Much evidence suggests an association between vitamin D deficiency and chronic diseases such as obesity and dyslipidemia. Although genetic factors play an important role in the etiology of these diseases, only a few studies have investigated the relationship between vitamin D-related genes and anthropometric and lipid profiles. The aim of this study was to investigate the association of three vitamin D-related genes with anthropometric and lipid parameters in 542 adult individuals. We analyzed the rs2228570 polymorphism in the vitamin D receptor gene (VDR), rs2134095 in the retinoid X receptor gamma gene (RXRG) and rs7041 in the vitamin D-binding protein gene (GC). Polymorphisms were genotyped by TaqMan allelic discrimination. Gene-gene interactions were evaluated by the general linear model. The functionality of the polymorphisms was investigated using the following predictors and databases: SIFT (Sorting Intolerant from Tolerant), PolyPhen-2 (Polymorphism Phenotyping v2) and Human Splicing Finder 3. We identified a significant effect of the interaction between RXRG (rs2134095) and GC (rs7041) on low-density lipoprotein cholesterol (LDL-c) levels (P=.005). Furthermore, our in silico analysis suggested a functional role for both variants in the regulation of the gene products. Our results suggest that the vitamin D-related genes RXRG and GC affect LDL-c levels. These findings are in agreement with other studies that consistently associate vitamin D and lipid profile. Together, our results corroborate the idea that analyzing gene-gene interaction would be helpful to clarify the genetic component of lipid profile.