Vitamin D receptor gene polymorphisms and type 1 diabetes mellitus in a Korean population

Association between vitamin D receptor polymorphisms and diabetic retinopathy in Uygur Chinese with type 2 diabetes

PURPOSE

This study was to investigate the potential association between vitamin D receptor(VDR) gene polymorphisms and the risk of diabetic retinopathy(DR) in the Uygur population in China, focusing on four specific VDR gene single nucleotide polymorphisms(SNPs) as candidate SNPs.

METHODS

The study genotyped a total of 151 DR patients and 130 healthy controls from the Uygur population using the single-base terminal extension (SNaPshot) method for four VDR gene SNPs: rs1544410, rs7975232, rs2228570, and rs731236. Hardy-Weinberg equilibrium was assessed using the χ2 test. Genotype frequencies were determined by directly counting the genotypes and correlating them with population data. The χ2 test was utilized to compare allele and genotype frequencies between patients and controls.

RESULTS

Compared to the healthy control group, the study observed a significantly higher frequency of the "TT" genotype at rs1544410 in the DR group. Additionally, within the non-proliferative diabetic retinopathy (NPDR) group, a significantly higher frequency of the "AA" genotype at rs7975232 was noted. No significant differences were found in the comparison of all haplotypes between patients and controls.

CONCLUSIONS

The study concluded that the rs1544410 polymorphism is associated with DR, and the rs7975232 polymorphism is associated with susceptibility to NPDR in the Uygur population in China.

Assessment of vitamin D status and vitamin D receptor polymorphism in Egyptian children with Type 1 diabetes

BACKGROUND

The endocrine system of vitamin D regulates about 3 % of the human genome. Vitamin D exerts its actions via a nuclear vitamin D receptor (VDR) which in turn regulates insulin secretion from the pancreas. VDR gene polymorphisms could have an impact on how autoimmune illnesses like Type 1 diabetes mellitus (T1DM) develop. We aimed to explore the relation between T1DM and VDR gene polymorphisms in Egyptian diabetic children and their siblings.

METHODS

Enzyme-linked immunosorbent assay was used to quantify 25(OH) vitamin D in the study, which had 179 participants (group 1 = 85 diabetic children, group 2 = 57 siblings of the patients, group 3 = 37 healthy controls). Real-time polymerase chain reaction (RT-PCR) was used to analyze the genotyping of the VDR gene polymorphisms Apa-I (rs7975232), Fok-I (rs2228570), Taq-I (rs731236) and Bsm-I (rs1544410).

RESULTS

The mean serum 25(OH) vitamin D levels was significantly lower in T1DM patients (14.99 ± 9.24 ng/mL) and siblings (16.31 ± 7.96 ng/mL) compared to the controls (19.48 ± 7.42 ng/mL) (p = 0.031). The genotypes distribution of VDR Fok-I (rs2228570) and Bsm-I (rs1544410) polymorphisms showed a significant difference between patients, siblings and controls as P = 0.001 and 0.026 respectively, while the VDR ApaI and TaqI polymorphisms did not. FokI-A allele frequency was significantly lower in T1DM patients and siblings than in controls (p < 0.001). FokI-AA genotype had a statistical significant higher vitamin D levels than other genotypes with p value of 0.024.

CONCLUSION

Our study found that T1DM children had lower vitamin D levels, and VDR FokI and BsmI gene polymorphisms were linked to T1DM in Egyptian children. Determining the relationship between vitamin D levels and VDR polymorphisms, particularly the FokI and other genetic analyses may aid in the early diagnosis of T1DM in children.

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

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

Variants in the VDR Gene May Influence 25(OH)D Levels in Type 1 Diabetes Mellitus in a Brazilian Population

Vitamin D has been considered a strong contributing factor to type 1 diabetes mellitus (T1DM). Many studies have investigated polymorphisms in the VDR gene in association with T1DM in different populations, but there are still conflicting findings. This study aimed to evaluate the association of four variants in the VDR gene (rs7975232, rs1544410, rs731236, and rs2228570) with T1DM risk and vitamin D levels within a population from North Region, Brazil, as well as the influence of genomic ancestry on T1DM. A total of 65 T1DM patients and 83 non-T1DM patients were enrolled in this study. VDR gene polymorphisms were assessed using Sanger sequencing analysis. Genomic ancestry was analyzed using a set of 61 ancestry-informative markers. T1DM patients showed higher European genomic contribution and lower Native American genomic contribution when compared to non-T1DM patients. T1DM patients with AA genotype in rs1544410 or CC genotype in rs731236 had significantly lower 25(OH)D levels compared to the other two genotypes (p = 0.013 and p = 0.02, respectively), while T1DM with TT genotype in rs2228570 had higher 25(OH)D levels compared to CC + TC in the same polymorphism (p = 0.011). Our findings suggest that the association between 25(OH)D and T1DM may be modified by VDR variants, possibly influencing the development of this autoimmune disease.

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.

Association of vitamin D receptor gene polymorphism with type 1 diabetes mellitus risk in children: A protocol for systematic review and meta-analysis

BACKGROUND

Recent genetic association studies showed that there are contradictory results on the relationship between vitamin D receptor (VDR) gene polymorphisms and type 1 diabetes mellitus (T1DM) risk in children. The purpose of this systematic review is to collect the currently available evidence to evaluate the relationship between VDR gene polymorphisms and the risk of T1DM in children.

METHODS

Such medical databases as Wanfang Data, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, Chongqing VIP Chinese Science and Technology Periodical Database, PubMed, Embase, and Web of Science were extensively searched for relevant literatures published before June 2021 with the focus on the relationship between VDR gene polymorphisms and the risk of T1DM in children. The risk of bias was evaluated as per the Newcastle-Ottawa Scale by 2 independent researchers. Meta-analysis was performed to quantify the relationship between VDR gene polymorphisms and T1DM risk in children.

RESULTS

The results of this meta-analysis would be submitted to a peer-reviewed journal for publication.

CONCLUSION

The relationship between VDR gene polymorphisms and T1DM risk in children is explored via this meta-analysis.

ETHICS AND DISSEMINATION

Ethical approval was not required for this study. The systematic review will be published in a peer-reviewed journal, presented at conferences, and shared on social media platforms.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/Q8XA5.

Vitamin D receptor gene polymorphisms in Sudanese children with type 1 diabetes

Type 1 diabetes mellitus (T1DM) is a T cell mediated autoimmune disease. Vitamin D was found to suppress the incidence of diabetes when bind to its receptor (VDR), probably by suppressing T cell activations. Thus the VDR gene polymorphism may have an impact on pathophysiology of this disease. Since there was no consistent association between VDR polymorphisms and the risk of T1DM, this study aimed to investigate a VDR gene polymorphism in Sudanese children with T1DM. We examined the VDR gene Bsm1 (rs1544410), Apa1 (rs7975232), and Taq1 (rs731236) single nucleotide polymorphisms in 174 children with T1DM, and 56 children as control, and the association of these polymorphisms with the diabetic control. Among study patients, the majority (85.63%) of diabetic patients reported metabolically poor controlled (HbA1c > 8%). As compared with the control, patients with T1DM presented more commonly with Bsm1 B allele (p = 0.001; OR 0.283; 95% CI 0.131–0.609) and Taq1 T allele (p = 0.05; OR 2.429; 95% CI 1.073–5.496). Apa1 A allele was less common in patients with T1DM without statistical difference (p = 0.862; OR 1.085; 95% CI 0.546–2.156). Our study suggests that, Bsm1 and Taq1 polymorphisms of the VDR gene associated with the prevalence of T1DM.

No association between the vitamin D-binding protein (DBP) gene polymorphisms (rs7041 and rs4588) and multiple sclerosis and type 1 diabetes mellitus: A meta-analysis

Background

The association between polymorphisms in vitamin D-binding protein (DBP) gene and the risk of multiple sclerosis (MS) and type 1 diabetes mellitus (T1DM) has been investigated in many studies, but the studies showed controversial results. The rationale for this meta-analysis was to determine whether DBP polymorphisms increases the risk of MS and T1DM by pooling data.

Methods

Potentially relevant studies were searched using GWAS Catalog, PubMed, Embase, CNKI and WANFANG databases up to November 2019. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were performed to estimate the associations in a fixed-effects or random-effects model.

Results

A total of 13 studies were enrolled in this meta-analysis, including eight studies for MS and five for T1DM. The overall results showed that there was no significant association of DBP rs7041 and rs4588 polymorphisms with the risk of MS and T1DM under any genetic model. Similarly, subgroup analysis by ethnicity revealed that no significant association of rs7041 and rs4588 polymorphisms with the risk of MS and T1DM was observed in white or non-white racial groups.

Conclusions

This meta-analysis provides evidence that DBP rs7041 and rs4588 polymorphisms may not be associated with an increased risk in MS and T1DM. However, these findings need further validation by larger-scale epidemiological studies and genome-wide association studies (GWASs) in different populations.

Vitamin D receptor gene polymorphisms and the risk of the type 1 diabetes: a meta-regression and updated meta-analysis

BACKGROUND

The association between the polymorphisms in the vitamin D receptor (VDR) gene and the risk of type 1 diabetes mellitus (T1DM) has been evaluated in several studies. However, the findings were inconclusive. Thus, we conducted a meta-analysis to comprehensively evaluate the effect of VDR gene polymorphisms on the risk of T1DM.

METHODS

All relevant studies reporting the association between VDR gene polymorphisms and susceptibility to T1DM published up to May 2020 were identified by comprehensive systematic database search in ISI Web of Science, Scopus, and PubMed/MEDLINE. Strength of association were assessed by calculating of pooled odds ratios (ORs) and 95% confidence intervals (CIs). The methodological quality of each study was assessed according to the Newcastle-Ottawa Scale. To find the potential sources of heterogeneity, meta-regression and subgroup analysis were also performed.

RESULTS

A total of 39 case-control studies were included in this meta-analysis. The results of overall population rejected any significant association between VDR gene polymorphisms and T1DM risk. However, the pooled results of subgroup analysis revealed significant negative and positive associations between FokI and BsmI polymorphisms and T1DM in Africans and Americans, respectively.

CONCLUSIONS

This meta-analysis suggested a significant association between VDR gene polymorphism and T1DM susceptibility in ethnic-specific analysis.

Vitamin D level and gene polymorphisms in Korean children with type 1 diabetes

BACKGROUND

Vitamin D metabolism has been associated with type 1 diabetes.

OBJECTIVE

We aimed to clarify the association of 25-hydroxylase (CYP2R1) and 1α-hydroxylase (CYP27B1) with risk of developing type 1 diabetes in Korean children.

METHODS

In total, 252 children (96 type 1 diabetes and 156 healthy controls) under the age of 20 years were recruited. Serum 25-hydroxyvitamin D (25OHD) and 1α,25-dihydroxyvitamin D [1α,25(OH)₂ D] levels were determined. Allelic, genotypic, and haplotypic distribution of CYP2R1 (rs12794714, rs10766196, rs10741657, rs2060793, and rs10766197) and CYP27B1 (rs4646536, rs10877012, and rs3782130) polymorphisms were determined. Clinical and biochemical data were analyzed according to genotype.

RESULTS

Mean vitamin D level was considerably lower, and vitamin D deficiency was more prevalent in children with type 1 diabetes than in healthy controls. The GG genotype of CYP2R1 rs12794714 and AA genotype of CYP2R1 rs10766196 were significantly associated with risk of developing type 1 diabetes (odds ratio 2.00, 95% confidence interval 1.176-3.413 and odds ratio 1.88, 95% confidence interval 1.103-3.195, respectively). The GG+GA genotype of CYP2R1 rs12794714 and AA+AG genotype of CYP2R1 rs10766196 were associated with prevalent vitamin D deficiency in children with type 1 diabetes. These genotypes did not differ with respect to glycosylated hemoglobin and daily insulin requirement.

CONCLUSIONS

Serum 25OHD and 1α,25(OH)₂ D levels were lower in children with type 1 diabetes than in healthy controls. CYP2R1 rs12794714 and rs10766196 polymorphisms were associated with a higher risk of type 1 diabetes. Thus, polymorphisms in vitamin D metabolism may contribute to susceptibility to type 1 diabetes in Korean children.

Vitamin D receptor rs7975232, rs731236 and rs1544410 single nucleotide polymorphisms, and 25-hydroxyvitamin D levels in Egyptian children with type 1 diabetes mellitus: effect of vitamin D co-therapy

Purpose: We aimed to examine the possible association role of vitamin D and vitamin D receptor (VDR) single nucleotide polymorphisms (SNPs) in type 1 diabetes mellitus (T1DM) development, glycemic control and complications among a cohort of Egyptian children. Subjects and methods: A prospective case-control study has been conducted on 50 Egyptian children with T1DM who were comparable with 50 controls. Vitamin D and HbA1c were measured. VDR-SNPs [ApaI (rs7975232), TaqI (rs731236) and BsmI (rs1544410)] detection was done by polymerase chain reaction through restriction fragment length polymorphism (PCR-RFLP) technique. Vitamin D supplements were given to the included T1DM children with low vitamin D and reassessments of both HbA1c% and 25(OH)D serum levels were performed in those children three months later. Results: Eighty percent of the included diabetic patients have poor glycemic control. Vitamin D was deficient in 68% and insufficient in 16% of diabetic patients. Significant improvements in both vitamin D and glycemic status among T1DM children, who have low vitamin D and received vitamin D supplementations. There were significantly negative correlations between serum levels of vitamin D with both HbA1c % (r= -0.358, P˂0.05) and daily insulin dose (r=-0.473, P˂0.05). Compared with controls, T1DM children presented more commonly with ApaI a allele (OR: 2.87; 95%CI: 1.39-5.91, P˂0.05) and BsmI b allele (OR: 4.38; 95%CI: 2.30-8.33, P˂0.05). TaqI t allele wasn't significantly differing among patients and controls (P˃0.05). Aa+aa and Bb+bb genotypes were significantly higher among T1DM vs the controls (OR: 3.08;, 95%CI: 1.33-7.15, P˂0.05 and OR: 9.33; 95%CI: 3.61-24.17, P˂0.05respectively). Conclusion: ApaI and BsmI were associated with risk of T1DM development among Egyptian children. Low vitamin D status was frequently occurring among T1DM with significant improvement in the glycemic control of such children when adding vitamin D supplements to the standard insulin therapy.

Relationship of four vitamin D receptor gene polymorphisms with type 1 diabetes mellitus susceptibility in Kuwaiti children

Background

The incidence of type 1 diabetes mellitus (T1DM) in Kuwait is amongst the highest in the world. Vitamin D is considered to be involved in immune modulation and its deficiency contribute to autoimmune destruction of insulin producing beta cells in T1DM patients. Vitamin D has been shown to exert its effects via a nuclear vitamin D receptor (VDR) and therefore, VDR gene may be considered a candidate for T1DM susceptibility.

Methods

The genotypes of four VDR gene polymorphisms were determined in 253 Kuwaiti Arab T1DM patients and 214 healthy controls by PCR-RFLP analysis. Serum concentrations of three autoantibodies i.e. ICA (Islet cell autoantibody), GADA (Glutamic acid decarboxylase) and INS (Insulin autoantibody) were determined by radio-immunoassays.

Results

Statistically significant differences were detected between the genotypes of two VDR gene polymorphisms (FokI, C > T, rs10735810 and TaqI, C > T, rs731236) between T1DM patients and controls (P < 0.0001). In both, the frequency of variant alleles was considerably high in T1DM than in the controls. In contrast, the VDR gene ApaI (G > T, rs7975232) and BsmI (A > G, rs1544410) polymorphisms did not show association with T1DM. The homozygous variant genotypes of FokI, ApaI and TaqI polymorphisms show significant differences between various age-of-onset subgroups while no such association was detected in the case of BsmI polymorphism. Significant differences were also noted between heterozygous genotypes of all four polymorphisms especially between 4-6y and > 6y age-of-onset subgroups of T1DM patients. Three autoantibodies, ICA (Islet cell), GADA (glutamate decarboxylase) and INS (insulin) were positively associated to, varying degrees, with T1DM in Kuwaiti Arabs harboring different VDR gene polymorphism genotypes.

Conclusions

Our results demonstrate a significant effect of two VDR gene polymorphisms (FokI and TaqI) and three autoantibodies on genetic susceptibility of T1DM in Kuwaiti Arabs along with other factors.

Understanding of type 1 diabetes mellitus: what we know and where we go

The incidence of type 1 diabetes mellitus (T1DM) in children and adolescents is increasing worldwide. Combined effects of genetic and environmental factors cause T1DM, which make it difficult to predict whether an individual will inherit the disease. Due to the level of self-care necessary in T1DM maintenance, it is crucial for pediatric settings to support achieving optimal glucose control, especially when adolescents are beginning to take more responsibility for their own health. Innovative insulin delivery systems, such as continuous subcutaneous insulin infusion (CSII), and noninvasive glucose monitoring systems, such as continuous glucose monitoring (CGM), allow patients with T1DM to achieve a normal and flexible lifestyle. However, there are still challenges in achieving optimal glucose control despite advanced technology in T1DM administration. In this article, disease prediction and current management of T1DM are reviewed with special emphasis on biomarkers of pancreatic β-cell stress, CSII, glucose monitoring, and several other adjunctive therapies.

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.

Inherited Variation in Vitamin D Genes and Type 1 Diabetes Predisposition

The etiology and pathophysiology of type 1 diabetes remain largely elusive with no established concepts for a causal therapy. Efforts to clarify genetic susceptibility and screening for environmental factors have identified the vitamin D system as a contributory pathway that is potentially correctable. This review aims at compiling all genetic studies addressing the vitamin D system in type 1 diabetes. Herein, association studies with case control cohorts are presented as well as family investigations with transmission tests, meta-analyses and intervention trials. Additionally, rare examples of inborn errors of vitamin D metabolism manifesting with type 1 diabetes and their immune status are discussed. We find a majority of association studies confirming a predisposing role for vitamin D receptor (VDR) polymorphisms and those of the vitamin D metabolism, particularly the CYP27B1 gene encoding the main enzyme for vitamin D activation. Associations, however, are tenuous in relation to the ethnic background of the studied populations. Intervention trials identify the specific requirements of adequate vitamin D doses to achieve vitamin D sufficiency. Preliminary evidence suggests that doses may need to be individualized in order to achieve target effects due to pharmacogenomic variation.

Association of vitamin D receptor polymorphisms and type 1 diabetes susceptibility in children: a meta-analysis

BACKGROUND

There have been studies focused on FokI, BsmI, ApaI and TaqI polymorphisms of the vitamin D receptor (VDR) gene and susceptibility to type 1 diabetes mellitus with controversial results.

METHODS

This present study is a meta-analysis investigating the association between FokI, ApaI, TaqI and BsmI polymorphisms of VDR gene and type 1 DM in children. A literature search was performed using Medline, EMBASE, Cochrane and PubMed. Any study was considered eligible for inclusion if at least one of FokI, ApaI, TaqI and BsmI polymorphisms was determined, and outcome was type 1 DM at pediatric age.

RESULTS

A total of 9 studies comprising 1053 patients and 1017 controls met the study inclusion criteria. The pooled odds ratios (ORs) of the FokI, ApaI, TaqI and BsmI polymorphisms were combined and calculated. Forest plots and funnel plots of the OR value distributions were drawn. Our meta-analysis has demonstrated statistically significant associations between DM1 and VDR genotypes, BsmIBB (P < 0.05), BsmIBb, (P < 0.05), BsmIbb (P < 0.05), TaqITT (P < 0.05) and TaqItt (P < 0.05) in children.

CONCLUSION

The results indicated that BsmIBB, BsmIBb and TaqItt polymorphisms were associated with an increased risk of type 1 DM, whereas BsmIbb and TaqITT had protective effect for type 1 DM in children.

The Role of Vitamin D in Diabetes and Cardiovascular Disease: An Updated Review of the Literature

The dietary reference values for Vitamin D were set primarily considering its role in bone health, but with the discovery of Vitamin D receptors throughout body tissues, new links with other health conditions are now studied, such as for diabetes and cardiovascular diseases (CVD). This paper shall analyze and examine all new research studies carried out, especially in 2013–2015 regarding diabetes mellitus (DM) and cardiovascular diseases (CVD). Vast research has been carried out to establish strong relationship between Vitamin D serum levels, supplementation, diabetes, and CVD. However, the results from researches identified in this paper are disputable. Benefits of Vitamin D adequate levels were recognized from gestational period until later in disease development such as diabetes and/or CVD, but since not all studies are in agreement further investigation is suggested. Researches conducting large randomized controlled trials, exploring range of supplement doses, with variable baseline serum Vitamin D levels, and inclusion of array of associated parameters, are still required to conduct large-scale analysis and draw conclusion as a risk factor. Until then it is possible to conclude that maintenance of serum Vitamin D levels holds advantageous aspects in diabetic and cardiovascular conditions, and people should strive to attain them.

Association between vitamin D receptor polymorphisms and osteoporosis in patients with COPD

BACKGROUND

Patients with COPD are at an increased risk of osteoporosis. Although many studies have addressed the relationship between the vitamin D receptor (VDR) polymorphisms and bone health, this relationship has not been fully investigated in patients with COPD. In this study, we investigated the association of VDR polymorphisms with bone mineral density (BMD) and other clinical parameters in patients with COPD.

PATIENTS AND METHODS

In total, 200 patients with COPD were included in this study. The VDR polymorphisms rs1544410 (A/G-BsmI), rs7975232 (A/C-ApaI), rs731236 (C/T-TaqI), and rs10735810 (C/T-FokI) were determined by Sanger sequencing using blood DNA samples. BMD of the lumbar vertebra and the femoral neck was measured by dual-energy X-ray absorptiometry. Other clinical parameters were also evaluated. Haplotype and multivariate analyses were also performed.

RESULTS

Sex, body mass index, steroid use, percentage of forced expiratory volume in 1 second (FEV1), alkaline phosphatase, and 25-hydroxyvitamin D significantly influenced the risk of osteoporosis. Patients with osteoporosis were more likely to carry the rs7975232 C allele compared to normal patients with BMD. Haplotypes GCT and GAT were related to osteoporosis. Patients without the haplotype GAT allele showed a significantly lower T-score at the femoral neck and an increased risk of osteoporosis (odds ratio [OR]= 2.78, 95% confidence interval [CI]= 1.20-6.48, P=0.018) compared with carriers in the dominant model.

CONCLUSION

Genetic variations in VDR are significantly associated with osteoporosis among patients with COPD. Further studies are required to confirm the role of the VDR polymorphisms in osteoporosis among patients with COPD.