Consequences of vitamin D receptor gene polymorphisms for growth inhibition of cultured human peripheral blood mononuclear cells by 1, 25-dihydroxyvitamin D3

Association of VDR Polymorphisms with Muscle Mass Development in Elite Young Soccer Players: A Pilot Study

The vitamin D receptor (VDR) is an important candidate gene in musculoskeletal phenotypes. Polymorphisms in the VDR have been previously associated with several pathologies and muscular strength in athletes and elderly people; however, the literature reported contradictory results. The object of this research was to verify the association between the most studied VDR variants (rs2228570, rs7975232, and rs1544410) and the increase in muscle mass in elite young soccer players. A sample of 55 soccer players (15-18 years old) from a professional team were selected for this study. DNA was extracted by the salting-out method, and polymorphisms were genotyped by PCR-RFLP, followed by 2% agarose gel electrophoresis. To test the effect of the three SNPs (single nucleotide polymorphisms), a logistic regression analysis was applied. The body composition determination was carried out through the skinfold thickness method, and the muscular area of the arm and lower limb were calculated using the Frisancho formula. All three polymorphisms met the Hardy-Weinberg equilibrium (p > 0.05) and their frequencies fell within the worldwide variability. A significant correlation between rs1544410 and the increase in calf muscle mass was observed. Individuals carrying the A allele showed higher calf muscular mass than those carrying the G allele (p = 0.034). Moreover, a haplotype analysis applied to the two SNPs in linkage disequilibrium (rs7975232 and rs1544410) showed that the AG haplotype appeared negatively correlated to the calf muscle area. In conclusion, we confirm an association between VDR polymorphisms and muscular mass that could encourage the genetic screening of the VDR gene to identify a potential risk of injury and for individual nutritional interventions.

Single-nucleotide polymorphisms related to vitamin D metabolism and severity or mortality of COVID-19: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to verify the association between single-nucleotide polymorphisms (SNPs) in vitamin D-related genes and the severity or mortality of coronavirus disease 19 (COVID-19). We systematically searched PubMed, BVS/Bireme, Scopus, Embase, and Web of Science for relevant studies published until November 24, 2023. Twelve studies were included. Thirty-one SNPs related to four genes were studied (VDR, 13 SNPs; GC, 6 SNPs; DHCR7/NADSYN1, 6 SNPs; CYP2R1, 6 SNPs). Eight SNPs were examined in two or more studies (VDR rs731236, rs2228570, rs1544410, rs7975232, rs739837, rs757343, rs11568820, and rs4516035). Meta-analysis showed a significant association between the VDR rs1544410 Bb + bb genotype and b allele and an increased odds of developing severe/critical COVID-19 (Bb + bb vs. BB = 2 studies, OR = 1.73, 95% confidence interval (CI): 1.16-2.57, P = 0.007, I2 = 0%; b allele vs. B allele = 2 studies, OR = 1.31, 95% CI: 1.03-1.67; P = 0.03; I2 = 0%). Regarding the mortality rate, VDR rs731236 TT-genotype, TT + Tt genotype, and T allele; VDR rs1544410 bb-genotype, Bb + bb genotype, and b allele; VDR rs7975232 AA-genotype, AA + Aa genotype, and A allele; and VDR rs2228570 ff-genotype, Ff + ff genotype, and f allele were associated with increased odds of death due to COVID-19. In conclusion, the present study suggests that SNPs rs1544410 may serve as a predictive biomarker for COVID-19 severity and rs731236, rs1544410, rs7975232, and rs2228570 as predictive biomarkers for COVID-19 mortality. More well-designed studies involving a larger number of COVID-19 patients are required to validate and replicate these findings.

Associations of vitamin D receptor polymorphisms with risk of Alzheimer's disease, Parkinson's disease, and mild cognitive impairment: a systematic review and meta-analysis

Vitamin D is a lipid soluble steroid hormone, which plays a critical role in the calcium homeostasis, neuronal development, cellular differentiation, and growth by binding to vitamin D receptor (VDR). Associations between VDR gene polymorphism and Alzheimer's disease (AD), Parkinson's disease (PD), and mild cognitive impairment (MCI) risk has been investigated extensively, but the results remain ambiguous. The aim of this study was to comprehensively assess the correlations between four VDR polymorphisms (FokI, BsmI, TaqI, and ApaI) and susceptibility to AD, PD, and MCI. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to determine the relationship of interest. Pooled analyses suggested that the ApaI polymorphism decreased the overall AD risk, and the TaqI increased the overall PD susceptibility. In addition, the BsmI and ApaI polymorphisms were significantly correlated with the overall MCI risk. Stratified analysis by ethnicity further showed that the TaqI and ApaI genotypes reduced the AD predisposition among Caucasians, while the TaqI polymorphism enhanced the PD risk among Asians. Intriguingly, carriers with the BB genotype significantly decreased the MCI risk in Asian descents, and the ApaI variant elevated the predisposition to MCI in Caucasians and Asians. Further studies are need to identify the role of VDR polymorphisms in AD, PD, and MCI susceptibility.

Association Between Vitamin D Receptor Polymorphism and the Response to Helicobacter Pylori Treatment

Background & Aims

This research aimed to determine how variations in the vitamin D receptor gene affected the response of H. pylori infections to eradication therapy.

Patients and Methods

On 105 adult H. Pylori-positive patients, a prospective cohort study was carried out. PCR was used to genotype all patients' VDR gene polymorphisms. The patients in the study received standard triple eradication medication (clarithromycin 500 mg, amoxicillin 1000 mg, and omeprazole 20 mg) twice daily for 14 days. A stool test for H. pylori Ag was conducted 4 weeks following the end of treatment.

Results

In our study, the usual triple therapy's H. pylori eradication rate was 75.2%. The successful eradication of H. pylori and VDR rs 2228570 gene polymorphisms was more prevalent in CT gene polymorphism (64.6%) compared to non-responders (19.2%), while treatment failure was more prevalent in CC gene polymorphism (73.1% in non-responders compared to responders 24.1%), which is statistically significant. In regards to the eradication of H. pylori and VDR rs7975232 gene polymorphisms, the success of eradication was more prevalent in AC gene polymorphism (54.4%) vs non-responders (30.4%), while all patients (14) with gene AA (17.7%) are responders to standard treatment, while the failure of treatment was more prevalent in CC gene polymorphism (69.2% in non-responder vs 27.8% in responders) which is statistically significant. Our findings demonstrated a strong correlation between patients' responses to H. pylori treatment and polymorphisms in the VDR gene (ApaI and TaqI) (P 0.05).

Conclusion

As far as we are aware, this is the first study to identify a potential link between the FokI and Apal VDR polymorphism and treatment response in H pylori-positive patients. To evaluate the findings, more research with larger number of patients and different population is required.

Implications of vitamin D deficiency in systemic inflammation and cardiovascular health

Clinical, epidemiological, and molecular studies have sufficiently highlighted the vitality of vitamin D [25(OH)D and 1,25(OH)2D] in human health and wellbeing. Globally, vitamin D deficiency (VDD) has become a public health concern among all age groups. There is a very high prevalence of VDD per the estimates from several epidemiological studies on different ethnic populations. But, population-specific scales do not support these estimates to define VDD clinically and consistent genetic associations. However, clinical studies have shown the relevance of serum vitamin D screening and oral supplementation in improving health conditions, pointing toward a more prominent role of vitamin D in health and wellness. Routinely, the serum concentration of vitamin D is measured to determine the deficiency and is correlated with physiological conditions and clinical symptoms. Recent research points toward a more inclusive role of vitamin D in different disease pathologies and is not just limited to otherwise bone health and overall growth. VDD contributes to the natural history of systemic ailments, including cardiovascular and systemic immune diseases. Considering its significant impact on premature morbidity and mortality, there is a compelling need to comprehensively review and document the direct and indirect implications of VDD in immune system deregulation, systemic inflammatory conditions, and cardio-metabolism. The recommendations from this review call for furthering our research concerning vitamin D and its direct and indirect implications.

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.

The association between single nucleotide polymorphisms and ovarian cancer risk: A systematic review and network meta-analysis

BACKGROUND

The relationship between single nucleotide polymorphisms (SNPs) and ovarian cancer (OC) risk remains controversial. This systematic review and network meta-analysis was aimed to determine the association between SNPs and OC risk.

METHODS

Several databases (PubMed, EMBASE, China National Knowledge Infrastructure, Wanfang databases, China Science and Technology Journal Database, and China Biology Medicine disc) were searched to summarize the association between SNPs and OC published throughout April 2021. Direct meta-analysis was used to identify SNPs that could predict the incidence of OC. Ranking probability resulting from network meta-analysis and the Thakkinstian's algorithm was used to select the most appropriate gene model. The false positive report probability (FPRP) and Venice criteria were further tested for credible relationships. Subgroup analysis was also carried out to explore whether there are racial differences.

RESULTS

A total of 63 genes and 92 SNPs were included in our study after careful consideration. Fok1 rs2228570 is likely a dominant risk factor for the development of OC compared to other selected genes. The dominant gene model of Fok1 rs2228570 (pooled OR = 1.158, 95% CI: 1.068-1.256) was determined to be the most suitable model with a FPRP <0.2 and moderate credibility.

CONCLUSIONS

Fok1 rs2228570 is closely linked to OC risk, and the dominant gene model is likely the most appropriate model for estimating OC susceptibility.

The relationship between VDR polymorphisms and keratinocyte carcinomas: a systematic review and meta-analysis

Aim: To perform a meta-analysis to assess the association between common VDR polymorphisms (Fok1, Taq1, Apa1, Bsm1) and keratinocyte carcinomas (KCs) susceptibility. Methods & materials: databases were searched up to November 2021. Odds ratios (OR) with 95% CIs were evaluated in the association. Results: This meta-analysis included seven articles. KC (and its subtypes) risks are found to be associated with Fok1 (BCC: ff vs FF+Ff: OR = 2.13, 95% CI = 1.14-3.97; SCC: ff vs FF+Ff: OR = 1.54, 95% CI = 1.09-2.18) and Taq1 (BCC: Tt vs TT: OR = 1.99, 95% CI = 1.35-2.93; tt vs TT: OR = 2.09, 95% CI = 1.27-3.43; Tt +tt vs TT: OR = 2.02, 95% CI = 1.41-2.90) polymorphisms. Conclusion: This study suggests that the Fok1 f allele and the Taq1 t allele are associated with increased susceptibility to KC and its subtypes.

Genetic Variability of the Vitamin D Receptor Affects Susceptibility to Parkinson’s Disease and Dopaminergic Treatment Adverse Events

Vitamin D is a lipid-soluble molecule and an important transcriptional regulator in many tissues and organs, including the brain. Its role has been demonstrated also in Parkinson’s disease (PD) pathogenesis. Vitamin D receptor (VDR) is responsible for the initiation of vitamin D signaling cascade. The aim of this study was to assess the associations of VDR genetic variability with PD risk and different PD-related phenotypes. We genotyped 231 well characterized PD patients and 161 healthy blood donors for six VDR single nucleotide polymorphisms, namely rs739837, rs4516035, rs11568820, rs731236, rs2228570, and rs1544410. We observed that VDR rs2228570 is associated with PD risk (p < 0.001). Additionally, we observed associations of specific VDR genotypes with adverse events of dopaminergic treatment. VDR rs1544410 (GG vs. GA + AA: p = 0.005; GG vs. GA: p = 0.009) was associated with the occurrence of visual hallucinations and VDR rs739837 (TT vs. GG: p = 0.036), rs731236 (TT vs. TC + CC: p = 0.011; TT vs. TC: p = 0.028; TT vs. CC: p = 0.035), and rs1544410 (GG vs. GA: p = 0.014) with the occurrence of orthostatic hypotension. We believe that the reported study may support personalized approach to PD treatment, especially in terms of monitoring vitamin D level and vitamin D supplementation in patients with high risk VDR genotypes.

Polymorphism of VDR Gene and the Sensitivity of Human Leukemia and Lymphoma Cells to Active Forms of Vitamin D

The active forms of vitamin D3 (calcitriol and tacalcitol) coupled to the vitamin D receptor (VDR) are known to exhibit anti-cancer properties. However, not all cancer cells are sensitive to the active forms of vitamin D3 and its analogs. The study aimed to determine whether polymorphism of VDR is responsible for the sensitivity of human leukemia and lymphoma cells to calcitriol and tacalcitol. The impact of calcitriol and tacalcitol on the proliferation and morphology of nine different leukemia and lymphoma cell lines was determined. Only MV-4-11, Thp-1, and HL-60 cell lines sensitive to proliferation inhibition by calcitriol and tacalcitol showed morphology changes. Subsequently, the levels of the VDR and 1,25D3-MARRS proteins of calcitriol and tacalcitol binding receptors and the VDR receptor polymorphism in human leukemia and lymphoma cells were ascertained. Contrary to the current understanding, higher levels of VDR are not responsible for the greater sensitivity of cells to calcitriol and tacalcitol. Importantly, we first showed that sensitivity to calcitriol and tacalcitol in leukemias and lymphomas could be determined by the VDR polymorphism. The FokI polymorphism and the presence of the "bat" haplotype were observed only in the sensitive cells.

25-OH Vitamin D blood serum linkage with VDR gene polymorphism (rs2228570) in thyroid pathology patients in the West-Ukrainian population

Vitamin D is known to alter immune regulation. It binds to the vitamin D receptors (VDR) expressed on T lymphocytes and macrophages. In individuals with Hashimoto’s thyroiditis, serum vitamin D levels were found to be lower compared to healthy controls. The study’s objective was to investigate the association between VDR gene polymorphism (rs2228570) with blood serum levels of 25-OH vitamin D in patients with thyroid pathology from western Ukraine. The study involved a total of 153 patients with various forms of thyroid pathology. 25-OH vitamin D levels in the serum of the patients and healthy individuals were quantified with ELISA using the 25-OH vitamin D Total (Vit D-Direct) Test System ELISA Kit (Monobind Inc.®, United States, Product Code: 9425-300) on the EIA Reader Sirio S (Seac, Italy). Genotyping of the VDR (rs2228570) gene polymorphism was performed using TaqMan probes and TaqMan Genotyping Master Mix (4371355) on CFX96™Real-Time PCR Detection System (Bio-Rad Laboratories, Inc., USA). Polymerase chain reaction (PCR) for TaqMan genotyping was carried out according to the kit instructions (Applied Biosystems, USA). Our research identified that that genotype variants of VDR rs2228570 are not risk factors for reduced serum 25-OH vitamin D or vitamin D deficiency in patients with various forms of thyroid pathology patients in the West-Ukrainian population. Vitamin D levels were significantly lower in the carriers of AA and AG genotypes with hypothyroidism caused by autoimmune thyroiditis. In AA genotype carriers with postoperative hypothyroidism, 25-OH vitamin D levels were significantly lower compared to AA genotype carriers with autoimmune thyroiditis.

Association of Vitamin D receptor gene polymorphisms and clinical/severe outcomes of COVID-19 patients

Introduction

Growing evidence documented the critical impacts of vitamin D (VD) in the prognosis of COVID-19 patients. The functions of VD are dependent on the vitamin D receptor (VDR) in the VD/VDR signaling pathway. Therefore, we aimed to assess the association of VDR gene polymorphisms with COVID-19 outcomes.

Methods

In the present study, eight VDR single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 500 COVID-19 patients in Iran, including 160 asymptomatic, 250 mild/moderate, and 90 severe/critical cases. The association of these polymorphisms with severity, clinical outcomes, and comorbidities were evaluated through the calculation of the Odds ratio (OR).

Results

Interestingly, significant associations were disclosed for some of the SNP-related alleles and/or genotypes in one or more genetic models with different clinical data in COVID-19 patients. Significant association of VDR-SNPs with signs, symptoms, and comorbidities was as follows: ApaI with shortness of breath (P ˂ 0.001) and asthma (P = 0.034) in severe/critical patients (group III); BsmI with chronic renal disease (P = 0.010) in mild/moderate patients (group II); Tru9I with vomiting (P = 0.031), shortness of breath (P = 0.04), and hypertension (P = 0.030); FokI with fever and hypertension (P = 0.027) in severe/critical patients (group III); CDX2 with shortness of breath (P = 0.022), hypertension (P = 0.036), and diabetes (P = 0.042) in severe/critical patients (group III); EcoRV with diabetes (P ˂ 0.001 and P = 0.045 in mild/moderate patients (group II) and severe/critical patients (group III), respectively). However, the association of VDR TaqI and BglI polymorphisms with clinical symptoms and comorbidities in COVID-19 patients was not significant.

Conclusion

VDR gene polymorphisms might play critical roles in the vulnerability to infection and severity of COVID-19, probably by altering the risk of comorbidities. However, these results require further validation in larger studies with different ethnicities and geographical regions.

The VDR FokI (rs2228570) polymorphism is involved in Parkinson's disease

The etiology of Parkinson's disease (PD) is presumably multifactorial and likely involves interactions between genetic and environmental factors, as well as mitochondrial dysfunction, oxidative stress and inflammation. Among environmental factors, Vitamin D was reported to associate with the risk of PD. Vitamin D activity is mediated by its binding to the vitamin D Receptor (VDR), a transcriptional factor for almost 3% of human genes. We genotyped for ApaI, BsmI, TaqI, FokI and rs1989969 VDR single nucleotide polymorphisms (SNPs) a cohort of 406 PD and 800 healthy controls (HC) and found a strong association between the FokI (rs2228570) VDR SNP and PD. Thus, the TT genotype and the T allele resulted associated with PD in the overall analyzed PD population. Gender-based stratification of data indicated that results were maintained for FokI TT genotype and T allele in male PD patients, whereas the FokI T allele alone was confirmed as a risk factor for PD in females. Co-segregation analyses indicated the TaqI ApaI FokI rs1989969 GCTG as a "risk" haplotype for PD. In a subgroup of patients and controls neural Vitamin D and VDR concentration was analyzed in extravesicles (NDEVs) isolated from peripheral blood: no differences emerged between PD and HC. NDEVs results will need to be validated in ampler cohort but we can speculate that, if at neuronal level the amounts of Vitamin D and of VDR are comparable, than the bioavailability of vitamin D and the efficacy of the vitamin D/VDR axis is differentially modulated in PD by VDR SNPs.

The association between vitamin D receptor polymorphisms and tissue-specific insulin resistance in human obesity

BACKGROUND/OBJECTIVES

To investigate (1) the association of four VDR polymorphisms (TaqI/rs731236, ApaI/rs7975232, FokI/rs10735810, and Bsml/rs1544410) with markers of adiposity and tissue-specific insulin resistance at baseline, after weight loss and weight maintenance; (2) the effect of the VDR polymorphisms in the SAT transcriptome in overweight/obese Caucasians of the DiOGenes cohort.

METHODS

We included 553 adult obese individuals (mean BMI 34.8 kg/m²), men (n = 197) and women (n = 356) at baseline, following an 8-week weight loss intervention and 26 weeks weight maintenance. Genotyping was performed using an Illumina 660W-Quad SNP chip on the Illumina iScan Genotyping System. Tissue-specific IR was determined using Hepatic Insulin Resistance Index (HIRI), Muscle Insulin Sensitivity Index (MISI), and Adipose Tissue Insulin Resistance Index (Adipo-IR). Expression quantitative trait loci (eQTL) analysis was performed to determine the effect of SNPs on SAT gene expression.

RESULTS

None of the VDR polymorphisms were associated with HIRI or MISI. Interestingly, carriers of the G allele of VDR FokI showed higher Adipo-IR (GG + GA 7.8 ± 0.4 vs. AA 5.6 ± 0.5, P = 0.010) and higher systemic FFA (GG + GA: 637.8 ± 13.4 vs. AA: 547.9 ± 24.7 µmol/L, P = 0.011), even after adjustment with age, sex, center, and FM. However, eQTL analysis showed minor to no effect of these genotypes on the transcriptional level in SAT. Also, VDR polymorphisms were not related to changes in body weight and IR as result of dietary intervention (P > 0.05 for all parameters).

CONCLUSIONS

The VDR Fokl variant is associated with elevated circulating FFA and Adipo-IR at baseline. Nevertheless, minor to no effect of VDR SNPs on the transcriptional level in SAT, indicating that putative mechanisms of action remain to be determined. Finally, VDR SNPs did not affect dietary intervention outcome in the present cohort.

Ethnicity as modifier of risk for Vitamin D receptors polymorphisms: Comprehensive meta-analysis of all cancer sites

Vitamin D receptors polymorphisms are found to be associated with several cancers. Since their prevalence vary across ethnicities and ethnicity itself seems to influence the cancer risk, a comprehensive meta-analysis was performed to investigate the role of VDR Fok1, Bsm1, Taq1, Apa1, Cdx2 and cancer risk at specific organ sites. Odds ratios, calculated with random-effects models, summarized one-hundred-ninety-two independent studies for twenty-two cancer sites. Evidence was provided that Fok1, Bsm1, Cdx2, Apa1 and Taq1 are linked to cancer susceptibility for colorectal, lung, ovarian, skin, multiple myeloma and brain cancer. Stratifying by ethnicity, some differences were found, partially explained by minor allele frequency (MAF), for colorectal cancer, ovarian and prostate cancer in Caucasian and prostate cancer in Asian populations. In summary, ethnicity may be a modifier of cancer risk, in particular for hormone dependent cancers and it should be considered evaluating the effect of VDR on cancer risk.

Vitamin D receptor gene polymorphisms are associated with psoriasis susceptibility and the clinical response to calcipotriol in psoriatic patients

Psoriasis is a common genetic disease characterized by hyperproliferation and disordered maturation of keratinocytes. To date, many association studies between psoriasis and VDR gene have been conducted, but the results are controversial. Furthermore, vitamin D₃ analogue has anti-psoriatic activity; however, the clinical response is variable. This study was conducted to explore whether VDR gene polymorphisms are associated with psoriasis susceptibility and clinical response to calcipotriol in psoriatic patients. A total of 110 patients and 183 controls were genotyped for VDR gene polymorphisms rs2228570, rs731236, rs1544410 and rs7975232 by LDR method. SNP-based and haplotype-based association analyses were subsequently performed. Patients with PASI < 3 were treated with calcipotriol ointment monotherapy. After 6 weeks of therapy, the correlations between efficacy and the genotypes of each polymorphism were evaluated. The results showed that for rs7975232, allele A was significantly over-represented in psoriasis patients relative to controls (39.09% vs. 27.05%, OR (95% CI) = 1.731 (1.213-2.471)), and compared with the reference CC genotype, the following ORs were observed: AA genotype OR = 2.404 (95% CI: 1.085-5.328; P = .034) and GA genotype OR = 2.143 (95% CI: 1.283-3.579; P = .005). Haplotype analyses showed that the rs2228570/rs731236/rs1544410/rs7975232 CTGA was significantly over-represented in psoriasis patients compared with controls (OR (95% CI)=1.907 (1.132-3.214); P = .020). Among the patients with PASI < 3, the response rates to calcipotriol were significantly higher in patients with rs7975232 CC genotypes than in those with other genotypes (x²  = 9.172, P = .010). These data suggest that VDR polymorphisms are associated with psoriasis susceptibility and clinical response to calcipotriol in psoriatic patients.

Association of vitamin D receptor genetic variants with bone mineral density and inflammatory markers in rheumatoid arthritis

BACKGROUND AND AIMS

Vitamin D receptor (VDR) genetic variants are considered to have a role in the pathogenesis of rheumatoid arthritis (RA). This study examines an association of FokI, BsmI, ApaI and TaqI with RA, as well as with bone mineral density (RA with normal bone mineral density, RA-NBMD; RA with associated osteopenia, RA-OSTP; and RA with associated osteoporosis, RA-OP) and inflammatory markers.

MATERIALS AND METHODS

VDR genetic variants were tested in 248 subjects using the PCR-RFLP method.

RESULTS

Significant differences were observed in the distribution of FokI genotypes between RA patients (p < 0.001), or subgroups (RA-NBMD, RA-OSTP, RA-OP) (p = 0.035, p = 0.02, p < 0.001, respectively) and controls. Prevalence of FokI f allele was significantly higher in RA group (p < 0.001) and subgroups (p = 0.003, p = 0.021, p < 0.001, respectively) compared to controls. An increased susceptibility to RA-OSTP was revealed in BsmI/ApaI Ba (AC) haplotype carriers (p = 0.012). A significantly higher erythrocyte sedimentation rate values were obtained in FokI FF compared to Ff + ff carriers (54.57 ± 23.73 vs. 22.83 ± 12.42; p < 0.001) within the RA-NBMD subgroup.

CONCLUSION

The results of the study indicate an association of RA with FokI genetic variant and increased susceptibility to RA in f allele carriers, as well as to RA-OSTP in BsmI/ApaI Ba (AC) haplotype carriers.

Relation of vitamin D and BsmI variant with temporomandibular diseases in the Turkish population

Vitamin D (VD) levels and several variants in the vitamin D receptor (VDR) gene are associated with the occurrence of diseases of the bones and cartilage. The aim of this research was to study and compare the association of the BsmI variant in the VDR gene as well as VD levels in disc displacement with reduction (DDR) between patients and healthy controls. This was a case-control study, in which 104 patients of DDR and 102 healthy individuals were studied. The Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) was used to diagnose temporomandibular diseases. The VDR BsmI variant was investigated, after extraction of genomic DNA, by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and the VD level in serum was measured. The serum VD level was significantly different between the patient and the control group (mean (SD) 13.20 (11.02) ng/mL versus 18.44 (10.03) ng/mL, respectively) (p=0.008). Serum VD assessment revealed that serious vitamin D deficiency was more prevalent in the patients than the controls (50.96% versus 21.56%) (p=0.00001). Logistic regression analysis revealed that the bb genotype and b allele carriers of VDR BsmI variant were significantly associated with increased risk of DDR (p=0.022 and p=0.01, respectively). VDR BsmI BB genotype was higher in the control group than the patient group (p=0.045). Genotype distributions for BsmI variant in the controls and the patients were confirmed using the Hardy-Weinberg equilibrium equation. The BsmI variant of the VDR gene and VD deficiency play role in DDR aetiopathogenesis in a Turkish population. Vitamin D level and VDR BsmI variation may be effective in a possible genetic-based DC/TMD Axis III to be created in the future.

Meta-Analysis of the Association Between the rs228570 Vitamin D Receptor Gene Polymorphism and Arterial Hypertension Risk

The association between FokI polymorphism in the vitamin D receptor (VDR) gene and susceptibility to arterial hypertension (HT) is controversial. Thus, we evaluated the relation between FokI and HT according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using MEDLINE® (Medical Literature Analysis and Retrieval System Online)/PubMed, Scopus, and Cochrane Library CENTRAL databases. Data from case-control studies, including the number of participants, age, 25-hydroxyvitamin D concentrations, systolic and diastolic blood pressure values, FokI allele, and genotype frequency were extracted by 2 independent authors and OR was calculated with the 95% CI to assess the strength of the association between the FokI variant and odds of HT. In general and subgroup analyses, we used allelic (f compared with F), common (ff compared with FF + Ff), risk (ff + Ff compared with FF), and additive (ff compared with FF) models. Six case-control studies including 3140 cases and 3882 controls were reviewed in the meta-analysis. Global assessment revealed a correlation between FokI and reduced odds of HT in the additive/homozygote model (ff compared with FF; OR: 0.65; 95% CI: 0.45-0.94) and common/recessive model (ff compared with FF + Ff; OR: 0.75; 95% CI: 0.57-0.99). In Asian subjects, there was a significant reduction in the odds of HT in additive (ff compared with FF; OR: 0.84; 95% CI: 0.73-0.98) and risk models (ff + Ff compared with FF; OR: 0.87, 95% CI: 0.78-0.97), in particular, for Indians (South). In Africans, the statistically significant association occurred in the additive and common models. Allele f in the FokI polymorphism of the VDR gene was associated with reduced odds of HT in the general population based on the risk model. Thus, nutritional genomics can help understand the influence of nutrition on metabolic homeostasis pathways and the clinical consequences of hypertension. This study shows the need for healthy, anti-inflammatory, and antioxidant compounds to prevent or treat chronic complications.

The genetic profile of elite youth soccer players and its association with power and speed depends on maturity status

We investigated the association of multiple single nucleotide polymorphisms (SNPs) with athlete status and power/speed performance in elite male youth soccer players (ESP) and control participants (CON) at different stages of maturity. ESP (n = 535; aged 8-23 years) and CON (n = 151; aged 9-26 years) were genotyped for 10 SNPs and grouped according to years from predicted peak-height-velocity (PHV), i.e. pre- or post-PHV, to determine maturity status. Participants performed bilateral vertical countermovement jumps, bilateral horizontal-forward countermovement jumps, 20m sprints and modified 505-agility tests. Compared to CON, pre-PHV ESP demonstrated a higher ACTN3 (rs1815739) XX ('endurance') genotype frequency distribution, while post-PHV ESP revealed a higher frequency distribution of the PPARA (rs4253778) C-allele, AGT (rs699) GG genotype and NOS3 (rs2070744) T-allele ('power' genotypes/alleles). BDNF (rs6265) CC, COL5A1 (rs12722) CC and NOS3 TT homozygotes sprinted quicker than A-allele carriers, CT heterozygotes and CC homozygotes, respectively. COL2A1 (rs2070739) CC and AMPD1 (rs17602729) GG homozygotes sprinted faster than their respective minor allele carrier counterparts in CON and pre-PHV ESP, respectively. BDNF CC homozygotes jumped further than T-allele carriers, while ESP COL5A1 CC homozygotes jumped higher than TT homozygotes. To conclude, we have shown for the first time that pre- and post-PHV ESP have distinct genetic profiles, with pre-PHV ESP more suited for endurance, and post-PHV ESP for power and speed (the latter phenotypes being crucial attributes for post-PHV ESP). We have also demonstrated that power, acceleration and sprint performance were associated with five SNPs, both individually and in combination, possibly by influencing muscle size and neuromuscular activation.

Precision (Personalized) Nutrition: Understanding Metabolic Heterogeneity

People differ in their requirements for and responses to nutrients and bioactive molecules in the diet. Many inputs contribute to metabolic heterogeneity (including variations in genetics, epigenetics, microbiome, lifestyle, diet intake, and environmental exposure). Precision nutrition is not about developing unique prescriptions for individual people but rather about stratifying people into different subgroups of the population on the basis of biomarkers of the above-listed sources of metabolic variation and then using this stratification to better estimate the different subgroups’ dietary requirements, thereby enabling better dietary recommendations and interventions. The hope is that we will be able to subcategorize people into ever-smaller groups that can be targeted in terms of recommendations, but we will never achieve this at the individual level, thus, the choice of precision nutrition rather than personalized nutrition to designate this new field. This review focuses mainly on genetically related sources of metabolic heterogeneity and identifies challenges that need to be overcome to achieve a full understanding of the complex interactions between the many sources of metabolic heterogeneity that make people differ from one another in their requirements for and responses to foods. It also discusses the commercial applications of precision nutrition.

Association Between Vitamin D Receptor Gene Polymorphisms and Helicobacter Pylori Infection

Background & Aims:

Human genetic polymorphism has been reported in the susceptibility and clinical development of infection. In this regard, this study aimed to investigate the link between Vitamin D Receptor (VDR) gene polymorphism and H. pylori infection.

Materials and Methods:

This cross-sectional study was conducted on 224 adult patients with upper gastrointestinal symptoms who underwent an upper gastrointestinal endoscopy between July 2017 and May 2019 in two major university hospitals. All patients were evaluated for helicobacter pylori infection. Two gastric antral biopsy specimens were taken from each patient. One of those Biopsy specimens was evaluated for histopathology examination and the other one was immersed in a saline solution ready for genomic DNA extraction.

Results:

There were statistically significant differences between different genotypes of VDR rs7975232 polymorphism between H. pylori infected and non-infected groups (CC was higher in H. pylori negative and AC and AA were the most common in H. pylori positive group). There were statistical differences between different genotypes of VDR rs2228570 between H. pylori infected and non-infected groups (TT was higher in H. pylori negative and CT and CC were the most common in H. pylori positive group). Regarding VDR rs 7975232 gene polymorphisms; the (A) allele was significantly higher H. pylori infected, while (C) allele was significantly higher in uninfected patients. Regarding VDR rs 2228570 gene polymorphisms; the (C) allele was significantly higher H. pylori infected, while (T) allele was significantly higher in uninfected patients.

Conclusion:

There is a possible association between the FokI and Apal VDR polymorphism and H. pylori infection.

Current understandings of the pathogenesis of type 1 diabetes: Genetics to environment

Type 1 diabetes (T1D) is an autoimmune disease that usually strikes early in life, but can affect individuals at almost any age. It is caused by autoreactive T cells that destroy insulin-producing beta cells in the pancreas. Epidemiological studies estimate a prevalence of 1 in 300 children in the United States with an increasing incidence of 2%-5% annually worldwide. The daily responsibility, clinical management, and vigilance required to maintain blood sugar levels within normal range and avoid acute complications (hypoglycemic episodes and diabetic ketoacidosis) and long term micro- and macro-vascular complications significantly affects quality of life and public health care costs. Given the expansive impact of T1D, research work has accelerated and T1D has been intensively investigated with the focus to better understand, manage and cure this condition. Many advances have been made in the past decades in this regard, but key questions remain as to why certain people develop T1D, but not others, with the glaring example of discordant disease incidence among monozygotic twins. In this review, we discuss the field’s current understanding of its pathophysiology and the role of genetics and environment on the development of T1D. We examine the potential implications of these findings with an emphasis on T1D inheritance patterns, twin studies, and disease prevention. Through a better understanding of this process, interventions can be developed to prevent or halt it at early stages.

Association of Fok1 VDR polymorphism with Vitamin D and its associated molecules in pulmonary tuberculosis patients and their household contacts

Status of Fok I VDR polymorphism along with vitamin D, Vitamin D receptor (VDR), and cathelicidin levels in Tuberculosis (TB) patients compared to household contacts and implication of these findings in susceptibility to TB is not known. 150 active TB patients, 150 household contacts and 150 healthy controls were recruited from North Indian population. Fok1 VDR polymorphism was studied by polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP).VDR mRNA and protein levels were studied using quantitative real time PCR (q rt PCR) and enzyme linked immunosorbent assay (ELISA) respectively. Cathelicidin and Vitamin D levels were measured using ELISA and chemiluminescence immunoassay (CLIA) respectively. Significant association was found between Fok1 polymorphism and susceptibility to TB (P < 0.0005). VDR mRNA, VDR protein and vitamin D levels were significantly lower in active TB group when compared to household contacts and healthy controls (P < 0.0001, 0.0001 and 0.0005 respectively). Cathelicidin levels were higher in active TB patients compared to other groups (P < 0.0001). Expression of VDR and cathelicidin was significantly higher among 'FF' genotypes of VDR (more active form of VDR) compared to 'ff' genotype (less active form of VDR). 'f' allele was associated with increased susceptibility to TB. Higher frequency of 'F' allele, increased VDR expression along with increased vitamin D levels in household contacts compared to active TB group might be responsible for protection against active TB.

Differential response of lung cancer cell lines to vitamin D derivatives depending on EGFR, KRAS, p53 mutation status and VDR polymorphism

Vitamin D reveals antiproliferative activity against many types of cancer cells. Calcitriol (1,25D3), the most active form of vitamin D3, acts mainly through the vitamin D receptor, regulating the expression of target genes. Cells with reasonable expression of VDR are considered to be sensitive to antiproliferative activity of 1,25D3. However, a few alleles of the VDR gene are correlated with higher or lower response to 1,25D3 treatment. The goal of our study was to establish if cells differing in EGFR, KRAS, p53 mutation status and VDR polymorphism were sensitive to antiproliferative activity of selected vitamin D derivatives (VDDs). In our search for the lead VDD against human lung cancer cells, we selected, for this study, low calcemic analogs of active forms of vitamin D2 and D3 that had previously shown anticancer potential. The selected cell lines revealed differential response to VDDs. The highest proliferation inhibition was observed for EGFR mutant cells while a weaker response was observed for KRAS and/or p53 mutant cells. 24,24-Dihomo-1,25D3 (PRI-1890) showed the highest activity on the VDD-sensitive cell lines (A549, HCC827, NCI-H1299, and NCI-H1703). Therefore, PRI-1890 was selected as the lead VDD for further structure optimization. None of the VDDs used in this study showed antiproliferative activity against A-427 and Calu-3. VDR polymorphisms correlated inversely with sensitivity to the antiproliferative activity of VDDs since we observed less transcriptionally active form of VDR in HCC827 cells sensitive to VDD, while more transcriptionally active form was observed in NCI-H358 cells that were stimulated by VDDs to proliferate. Lack of KRAS and p53 mutations in HCC827 cells may be, therefore, responsible for the higher antiproliferative activity of VDDs, while the presence of KRAS and/or p53 mutations in other cell lines might prevent antiproliferative activity even though the VDDs were transcriptionally active as assessed on increased CYP24A1 expression. VDR gene polymorphism is not directly responsible for the sensitivity of tested cells to VDDs.

Maternal vitamin D level and vitamin D receptor gene polymorphism as a risk factor for congenital heart diseases in offspring; An Egyptian case-control study

Vitamin D & vitamin D receptor (VDR) signaling play a very crucial role in early embryonic heart development. We construct this case-control study to investigate the association between maternal serum vitamin D level & VDR gene Fok1 polymorphism and risk of congenital heart defects (CHD) in offspring. Fifty mothers who had term neonates with CHD were considered as cases. Fifty age-comparable healthy mothers who had neonates without CHD were contemplated as controls. Maternal serum 25 hydroxyvitamin D [25(OH) D] level was tested using ELISA. Maternal VDR gene Fok1 polymorphism was analyzed using PCR-based RFLP-assay. There was a significant decrease in maternal vitamin D level (P = 0.002) and a significant increase in vitamin D deficient status (P = 0.007) among cases when compared to controls. VDR gene Fok1 genotypes distribution frequency were in accordance with Hardy Weinberg equilibrium (HW) among controls. A significant increase in VDR gene Fok1 F/f & f/f genotypes and f allele were observed in cases compared to controls with estimated odds ratio (95% confidence interval) & P-value of 3 (1-8) & P = 0.006, 11 (1-97) & P = 0.01 and 3 (2-6) & P = 0.001 respectively. There was a significant decrease in maternal vitamin D level in neonates with cyanotic CHD (P = 0.000) compared to those with a cyanotic CHD while there was no significant difference in VDR Fok1 genotype (P = 0.18) & allele (P = 0.05) distribution between two groups. We concluded that maternal vitamin D deficiency and VDR gene Fok1 F/f, f/f genotype and f allele were associated with increased risk of CHD in offspring.

Vitamin D Receptor gene polymorphisms and plasma levels are associated with lumbar disc degeneration

The purpose of this study was to investigate the association of Vitamin D Receptor (VDR) gene polymorphisms and VDR levels with lumbar disc degeneration (LDD). TaqMan SNP Genotyping Assay was utilized to probe VDR gene polymorphisms including the FokI (rs2228570), ApaI (rs7975232) and TaqI (rs731236) in 454 patients with LDD and 485 controls. Enzyme-Linked Immunosorbent Assay (ELISA) was used to detect plasma VDR levels. The patients with LDD were divided into three subgroups (subgroup 1: lumbar disc herniation; subgroup 2: lumbar spinal stenosis; subgroup 3: lumbar spondylolisthesis) to further probe the association of plasma VDR levels and VDR gene polymorphisms and LDD. Moreover, immunohistochemistry (IHC) was implemented to evaluate VDR expression in lumbar degenerated disc and normal disc. Allele and genotype frequency of TaqI (rs731236) were significantly different in patients with LDD and controls (all P < 0.05). For TaqI polymorphism, the frequencies of T allele were significantly higher in the LDD patients compared with controls (OR = 1.319; 95%CI 1.091 to 1.595; P = 0.004, adjusted (OR = 1.319; 95%CI 1.091 to 1.595; P = 0.004, adjusted OR = 1.383; 95%CI 1.135 to 1.684; P = 0.016). Furthermore, the allele distribution showed a higher frequency of the T allele in the patients with lumbar disc herniation in subgroup 1 (OR = 1.384; 95% CI 1.105 to 1.732; P = 0.004, adjusted OR = 1.319; 95%CI 1.091 to 1.595; P = 0.016). Plasma VDR levels and VDR expression were significantly lower in patients with LDD compared with controls (all P < 0.05). Moreover, the TT genotype of TaqI polymorphism was significantly associated with lower plasma VDR levels in patients with LDD (P = 0.002). TaqI (rs731236) polymorphism was associated with a predisposition to LDD. Plasma VDR and VDR expression levels may be the marker for the occurrence and development of LDD.

The interactions of physical activity, exercise and genetics and their associations with bone mineral density: implications for injury risk in elite athletes

Low bone mineral density (BMD) is established as a primary predictor of osteoporotic risk and can also have substantial implications for athlete health and injury risk in the elite sporting environment. BMD is a highly multi-factorial phenotype influenced by diet, hormonal characteristics and physical activity. The interrelationships between such factors, and a strong genetic component, suggested to be around 50-85% at various anatomical sites, determine skeletal health throughout life. Genome-wide association studies and case-control designs have revealed many loci associated with variation in BMD. However, a number of the candidate genes identified at these loci have no known associated biological function or have yet to be replicated in subsequent investigations. Furthermore, few investigations have considered gene-environment interactions-in particular, whether specific genes may be sensitive to mechanical loading from physical activity and the outcome of such an interaction for BMD and potential injury risk. Therefore, this review considers the importance of physical activity on BMD, genetic associations with BMD and how subsequent investigation requires consideration of the interaction between these determinants. Future research using well-defined independent cohorts such as elite athletes, who experience much greater mechanical stress than most, to study such phenotypes, can provide a greater understanding of these factors as well as the biological underpinnings of such a physiologically "extreme" population. Subsequently, modification of training, exercise or rehabilitation programmes based on genetic characteristics could have substantial implications in both the sporting and public health domains once the fundamental research has been conducted successfully.

The role of vitamin D in ovarian cancer: epidemiology, molecular mechanism and prevention

Vitamin D is a fat-soluble prohormone best known for its role in maintaining calcium homeostasis. Large numbers of epidemiological studies have shown that vitamin D plays an important role in cancer prevention by regulating cellular proliferation and metabolism. Studies of the cellular mechanism of vitamin D in ovarian cancer strongly suggest that it exhibits protective and antitumorigenic activities through genomic and nongenomic signal transduction pathways. These results indicate that vitamin D deficiency results in an increase in the risk of developing ovarian cancer and that vitamin supplements may potentially be an efficient way of preventing cancer. Consequently, this review describes the epidemiology, molecular mechanism and evidence linking vitamin D deficiency to ovarian cancer.

Challenge and perspective: the relevance of ultraviolet (UV) radiation and the vitamin D endocrine system (VDES) for psoriasis and other inflammatory skin diseases

During evolution, the ability of many organisms to synthesize vitamin D photochemically represented, and still represents, a major driving factor for the development of life on earth. In humans because not more than 10-20% of the requirement of vitamin D can be satisfied by the diet (under most living conditions in the US and Europe), the remaining 80-90% need to be photochemically synthesized in the skin through the action of solar or artificial ultraviolet-B (UV-B) radiation. The skin is a key organ of the human body's vitamin D endocrine system (VDES), representing both the site of vitamin D synthesis and a target tissue for biologically active vitamin D metabolites. Human keratinocytes contain the enzymatic machinery (CYP27B1) for the synthesis of the biologically most active natural vitamin D metabolite 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), representing an autonomous vitamin D₃ pathway. Cutaneous production of 1,25(OH)₂D₃ may mediate intracrine, autocrine and paracrine effects on keratinocytes and on neighboring cells. Many skin cells (including keratinocytes, sebocytes, fibroblasts, melanocytes, macrophages and other skin immune cells) express the vitamin D receptor (VDR), an absolute pre-requisite for exerting genomic effects of 1,25(OH)₂D₃ and analogs. The VDR is a member of the superfamily of trans-acting transcriptional regulatory factors, which also contains the steroid and thyroid hormone receptors as well as the retinoid-X receptors (RXR) and retinoic acid receptors (RAR). A large body of evidence, including cDNA microarray analyses of mRNAs, indicates that as many as 500-1000 genes may be controlled by VDR ligands that regulate a broad variety of cellular functions including growth, differentiation, and apoptosis. Clinical and laboratory investigations, including the observation that 1,25(OH)₂D₃ is very effective in inducing the terminal differentiation and in inhibiting the proliferation of cultured human keratinocytes have resulted in the use of 1,25(OH)₂D₃ and analogs for the treatment of psoriasis. Focussing on the UV-induced cutaneous synthesis of vitamin D, this review gives an update on the relevance of the VDES and of UV radiation for the management of psoriasis and other inflammatory skin diseases.

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.

Relationship of vitamin D receptor gene polymorphisms in Helicobacter pylori gastric patients

Purpose

The present study aimed to investigate the association between the human VDR gene and Helicobacter pylori infection.

Patients and methods

A cross-sectional study was conducted on 208 adult patients with upper gastrointestinal symptoms. Gastric biopsy specimens were obtained from each patient for molecular DNA and histological examination. Patients were genotyped for VDR gene polymorphisms using polymerase chain reaction and restriction fragment length polymorphism analysis.

Results

The allelic and genotypic distribution analyses of the FokI, ApaI and TaqI polymorphisms of the VDR gene did not show distribution differences between H. pylori-positive and -negative groups. The genotype distribution observed for polymorphism BsmI deviated significantly from what was expected in a Hardy–Weinberg equilibrium test in the H. pylori-positive group (χ²=29.048, p<0.001). The distribution of BsmI genotypes differed significantly between the H. pylori-negative and H. pylori-positive groups (p=0.0034), where the frequency of the bb genotype increased among H. pylori-positive individuals compared with those without infection (63.25% versus 50.55%, respectively). Conversely, the H. pylori-negative group showed a Bb frequency that was 20.27% higher than in the infected group.

Conclusion

We identified a possible association between the BsmI polymorphism and infection by H. pylori. However, further research is required to clarify this relationship.

Vitamin D Receptor Gene Polymorphisms Modify Cardiometabolic Response to Vitamin D Supplementation in T2DM Patients

There is conflicting evidence on the favorable effects of vitamin D supplementation on metabolic profile in Type 2 diabetes mellitus (T2DM) patients and this might be due to genetic variations in vitamin D receptors (VDRs). Thus, we studied the metabolic effects of a 12-month vitamin D supplementation in T2DM patients according to VDR polymorphisms. A total of 204 T2DM subjects received 2000 IU vitamin D3 daily for 12 months. Serum 25(OH)D and metabolic profiles were measured at baseline and after 12 months. VDR polymorphisms (Taq-I, Bsm-I, Apa-I and Fok-I) were identified using TaqMan genotyping assays. Vitamin D supplementation significantly increased HOMA β-cell function (p = 0.003) as well as significantly decreased triglycerides, total and LDL-cholesterol (p < 0.001). The lowest increment in 25(OH)D levels was detected in patients with Fok-I CC genotypes (p < 0.0001). With vitamin D supplementation, Taq-I GG genotype carriers showed significant improvements in triglycerides, LDL- and total cholesterol, insulin, HbA1c and HOMA-IR (p < 0.005, 0.01, < 0.001, < 0.005, 0.03 and 0.01, respectively). Similarly, Bsm-I TT genotype carriers showed significant improvements in triglycerides (p = 0.01), insulin and HOMA-IR (p-values < 0.05). In conclusion, improvements in metabolic profile due to vitamin D supplementation is influenced by VDR polymorphisms, specifically for carriers of Taq-I GG and Bsm-I TT genotypes.

Vitamin D Receptor Gene Polymorphisms in Serbian Patients With Bronchial Asthma: A Case-Control Study

Vitamin D and single nucleotide polymorphisms (SNPs) in vitamin D receptor (VDR) gene are potentially involved in the pathogenesis of bronchial asthma (BA); however, precise mechanisms by which vitamin D reduces the inflammation and the role of VDR SNPs in BA are not completely understood. The aim of this study was to examine the possible associations of FokI, BsmI, ApaI, and TaqI SNPs with BA. A total of 168 subjects were screened for VDR SNPs using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. The obtained results showed statistically significant differences in the distribution of FokI genotypes (df = 2; P = 0.008) and alleles (P = 0.002; OR = 0.446; 95%CI = 0.264-0.752) between patients and controls. Distributions of BsmI, ApaI, and TaqI genotypes and alleles did not show statistical differences. BsmI, ApaI, and TaqI SNPs are in linkage disequilibrium (LD) in the whole studied group, as well as in BA patients and controls. The strongest LD was observed between BsmI and TaqI (r²  = 0.69 for all subjects in the study; r²  = 0.75 in BA; r²  = 0.64 in controls), while lower values of LD were observed for BsmI and ApaI, and ApaI and TaqI SNPs. This is the first study that examined the association of VDR SNPs (FokI, BsmI, ApaI, and TaqI) in Serbian patients with BA indicating protective effect of FF genotype and F allele of FokI SNP on BA development. J. Cell. Biochem. 118: 3986-3992, 2017. © 2017 Wiley Periodicals, Inc.

Vitamin D receptor gene FokI but not TaqI, ApaI, BsmI polymorphism is associated with Hashimoto's thyroiditis: a meta-analysis

Four VD receptor (VDR) gene polymorphisms (TaqI, ApaI, FokI and BsmI) have been reported to influence Hashimoto’s thyroiditis (HT) risk. However, individual studies have produced inconsistent results. We conducted a comprehensive meta-analysis of eleven case-control studies to better understand roles of the four polymorphisms in HT development. The results showed only FokI polymorphism was significantly associated with the risk of HT (F vs f: OR = 1.44, 95% CI = 1.09–1.91, P = 0.010; FF vs Ff + ff: OR = 1.72, 95% CI = 1.09–2.70, P = 0.019). Subgroup analyses demonstrated the significant effect was only present in Asian population (F vs f: OR = 1.45, 95% CI = 1.07–1.95, P = 0.016; FF vs ff: OR = 1.64, 95% CI = 1.03–2.59, P = 0.036; FF + Ff vs ff: OR = 1.34, 95% CI = 1.00–1.80, P = 0.047; FF vs Ff + ff: OR = 1.64, 95% CI = 1.03–2.64, P = 0.039), but not in Caucasian. For TaqI, ApaI and BsmI polymorphisms, no significant association was found in any model comparison. Based on the current literature, it appears that only VDR FokI polymorphism is associated with HT risk in Asian population, but not in Caucasians; and the TaqI, ApaI and BsmI polymorphisms have not positive association neither in the overall population, nor when stratified by ethnicity. Further well-designed studies with larger sample sizes and different ethnic population are needed to clarify the present findings.

Targeting the vitamin D endocrine system (VDES) for the management of inflammatory and malignant skin diseases: An historical view and outlook

Vitamin D represents one of the major driving factors for the development of life on earth and for human evolution. While up to 10-20 % of the human organism's requirements in vitamin D can be obtained by the diet (under most living conditions in the USA and Europe), approximately 90 % of all needed vitamin D has to be photosynthesized in the skin through the action of the sun (ultraviolet-B (UV-B)). The skin represents a key organ of the human body's vitamin D endocrine system (VDES), being both the site of vitamin D synthesis and a target tissue for biologically active vitamin D metabolites. It was shown that human keratinocytes possess the enzymatic machinery (CYP27B1) for the synthesis of the biologically most active natural vitamin D metabolite 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), representing an autonomous vitamin D₃ pathway. Cutaneous production of 1,25(OH)₂D₃ may exert intracrine, autocrine, and paracrine effects on keratinocytes and on neighboring cells. Many skin cells (including keratinocytes, sebocytes, fibroblasts, melanocytes, and skin immune cells) express the vitamin D receptor (VDR), an absolute pre-requisite for the mediation of genomic effects of 1,25(OH)₂D₃ and analogs. VDR belongs to the superfamily of trans-acting transcriptional regulatory factors, which includes the steroid and thyroid hormone receptors as well as the retinoid X receptors (RXR) and retinoic acid receptors (RAR). Numerous studies, including cDNA microarray analyses of messenger RNAs (mRNAs), indicate that as many as 500-1000 genes may be regulated by VDR ligands that control various cellular functions including growth, differentiation, and apoptosis. The observation that 1,25(OH)₂D₃ is extremely effective in inducing the terminal differentiation and in inhibiting the proliferation of cultured human keratinocytes has resulted in the use of vitamin D analogs for the treatment of psoriasis. This review gives an historical view and summarizes our present knowledge about the relevance of the VDES for the management of inflammatory and malignant skin diseases.

Cdx-2 polymorphism in Vitamin D Receptor gene was associated with serum 25-hydroxyvitamin D levels, bone mineral density and fracture in middle-aged and elderly Chinese women

The aim of the current study was to examine the relationship between Cdx-2 polymorphism in the promoter region of the VDR gene and serum 25-hydroxyvitamin D (25(OH)D) levels, bone mineral density (BMD) and fracture in Chinese population. This was a cross-sectional study, which included 738 individuals (428 women and 310 men) aged 45 years or older. In women, the association of Cdx-2 polymorphism with serum 25(OH)D levels was significant adjusting for age, BMI, estimated glomerular filtration rate, menopausal status and season of blood collection (P = 0.002). Cdx-2 polymorphism was associated with lumbar spine BMD adjusted for age, BMI, menopausal status and serum 25(OH)D in women (P = 0.005). But it was not associated with femoral neck BMD or total hip BMD in women. In women, Cdx-2 polymorphism was also associated with fracture adjusted for age, BMI, menopausal status, serum 25(OH)D and total hip BMD (P = 0.03). Carriers of AA and AG genotypes was associated with a higher odds of fracture compared with the carriers of GG genotype (OR = 2.14, 95% CI 1.04-4.42 and OR = 1.90, 95% CI 1.03-3.51). In men, Cdx-2 polymorphism was not associated with serum 25(OH)D levels, BMD or fracture. Our results indicate that the association of Cdx-2 polymorphism in the VDR gene with serum 25(OH)D levels, BMD and fracture may have sex differences. Cdx-2 polymorphism in the VDR gene may affect the serum 25(OH)D concentrations and the risk of osteoporosis and fracture in middle-aged and elderly Chinese women.

Genetic variation in vitamin D receptor gene (Fok1:rs2228570) is associated with risk of coronary artery disease

OBJECTIVE

The Fok1 polymorphism (rs2228570) in vitamin D receptor gene appears to be the only polymorphism influencing size of translated protein. Investigations into its association with coronary artery disease (CAD) are sparse.

METHODS

Male patients (n = 98) with verified CAD were recruited alongside age- and sex-matched controls (n = 55). Genotyping was performed by PCR-RFLP and plasma 25-Hydroxyvitamin D levels were assessed by HPLC-UV.

RESULTS

The C-variant (mutant) was predominantly expressed in patients compared to controls (68.9% versus 55.5%; p = 0.025). The observed genotypes were not associated with 25-Hydroxyvitamin D levels.

CONCLUSION

This study presents Fok1 polymorphism as a potential genetic marker for CAD.

Genetic polymorphisms related to vitamin D and the therapeutic potential of vitamin D in multiple sclerosis

Vitamin D receptors (VDRs), which are responsible for most vitamin D functions, are expressed on various immune cells. Vitamin D is considered to be a potent immunomodulator. A variety of cells in the central nervous system (CNS) also express VDRs; thus, vitamin D may play a role in the regulation of neurodegeneration and repair processes within the CNS. Considered together with epidemiological studies, low vitamin D status is reckoned to be one of the risk factors for multiple sclerosis (MS). Further, vitamin D is considered to be a possible treatment for MS. However, previous clinical trials with small cohorts have not demonstrated significant effects of vitamin D in MS. Current ongoing clinical trials with large cohorts could provide answers with respect to the clinical effects of vitamin D in MS. However, genetic studies have suggested that genes associated with vitamin D, including VDRs, are susceptible genes for MS. Vitamin D needs to be considered from the perspective of the interaction between vitamin-D-related genetic factors and environmental factors affecting vitamin D levels.

VDR FokI polymorphism is associated with a reduced T-helper cell population under vitamin D stimulation in type 1 diabetes patients

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease mediated by T-helper (Th) cells. Additionally, the immune system regulator vitamin D, exerts its modulatory effects through the vitamin D receptor (VDR) expressed in Th cells. Furthermore, several genetic variants in the VDR gene including the VDR FokI (rs10735810) polymorphism have been implicated in T1D susceptibility in some Caucasian populations. Aim of the present study was to investigate the possible functional role of the VDR FokI gene polymorphism in Th cells from T1D patients and healthy controls (HC).

METHODS

Isolated Th cells from 23 HC and 20 T1D patients were stimulated for 72h with 25-hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). After in vitro culture CD3(+)CD4(+) (CD4(+)) Th cell subsets were characterized by flow cytometry and gene expression of VDR was measured by Taqman assay. Finally, the VDR FokI polymorphism was genotyped.

RESULTS

Significant lower VDR gene expression was observed in non-stimulated and 25(OH)D3 stimulated Th cells from T1D compared to HC (p=0.04 and p=0.005, respectively). In addition, by stratifying subjects into VDR FokI genotypes, significant lower percentage of CD4(+) cells was observed in 25(OH)D3 and 1,25(OH)2D3 stimulated Th cells from T1D patients carrying the "FF" genotype compared to those with the genotypes "Ff/ff" (p=0.02 and p=0.05, respectively). Moreover, looking at vitamin D effects according to VDR FokI genotypes, CD4(+) cells were significantly down-regulated by 25(OH)D3 and 1,25(OH)2D3 only in T1D "FF" carriers (p=0.01 and p=0.02; respectively).

CONCLUSION

According to these results, T1D patients carrying the "FF" genotype with an adequate vitamin D therapy may benefit from a more balanced T cell immunity. However, further research is needed to confirm these premilinary findings and to elucidate functional mechanisms of genetic variation in the vitamin D system. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Vitamin D receptor gene polymorphisms and steroid receptor status among Saudi women with breast cancer

The vitamin D receptor (VDR) is a mediator for the cellular effects of vitamin D and interacts with other cell signaling pathways that influence cancer development. We evaluated the associations of the FOK1 and Taq1 VDR polymorphisms and breast cancer risk and possible effect modification by steroid receptor status of the tumor. This case-control study includes 95 breast cancer patients and 100 age-matched controls. Genotyping for VDR FOK1 and Taq1 polymorphisms was performed using polymerase chain reaction-based restriction fragment length polymorphism. Level of 25(OH)D in serum was determined using ELISA. Immunohistochemical studies were performed for estrogen receptors (ER) and progesterone receptors (PR). The frequencies of ff genotype were significantly increased in the breast cancer group compared to the control group. Carriers of the f allele were significantly more likely to develop BC. We observed a statistically significant interaction for the Fok1 polymorphism and ER status. Our results demonstrated that FOK1 f. genotype and f allele have an important role in breast cancer risk in Saudi patients.

Vitamin D and skin cancer

Vitamin D signaling plays a key role in many important processes, including cellular proliferation, differentiation and apoptosis, immune regulation, hormone secretion and skeletal health. Furthermore, vitamin D production and supplementation have been shown to exert protective effects via an unknown signaling mechanism involving the vitamin D receptor (VDR) in several diseases and cancer types, including skin cancer. With over 3.5 million new diagnoses in 2 million patients annually, skin cancer is the most common cancer type in the United States. While ultraviolet B (UVB) radiation is the main etiologic factor for nonmelanoma skin cancer (NMSC), UVB also induces cutaneous vitamin D production. This paradox has been the subject of contradictory findings in the literature in regards to amount of sun exposure necessary for appropriate vitamin D production, as well as any beneficial or detrimental effects of vitamin D supplementation for disease prevention. Further clinical and epidemiological studies are necessary to elucidate the role of vitamin D in skin carcinogenesis.

Vitamin D receptor gene polymorphisms in Iranian Azary patients with Behçet's disease

OBJECTIVES

The aim of our study was to investigate the association of four polymorphisms of the VDR gene (FokI, BsmI, TaqI, and ApaI) with their susceptibility to Behçet's disease (BD) and their clinical manifestations with respect to the Iranian Azari population.

METHOD

In this cross-sectional study we considered the BsmI, FokI, ApaI, and TaqI polymorphisms in 50 Iranian Azary patients with BD and 50 healthy controls, with the use of polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP).

RESULTS

A significant difference was found for the FokI polymorphism between the case and control groups. The f allele frequency of 26% was present in BD patients, compared to only 13% in the control group. In addition, the f/f genotype was significantly associated with BD. We found no significant differences between the BD and control groups regarding the distribution of ApaI, BsmI, and TaqI genotype frequencies. We found no association between VDR polymorphisms and the clinical manifestations of BD.

CONCLUSIONS

The VDR f allele and f/f genotype are associated with BD in the Iranian Azari population.