Age- and gender-specific effects on VDR gene polymorphisms and risk of the development of multiple sclerosis in Tunisians: a preliminary study

MSGD: a manually curated database of genomic, transcriptomic, proteomic and drug information for multiple sclerosis

Multiple sclerosis (MS) is the most common inflammatory demyelinating disease of the central nervous system. 'Omics' technologies (genomics, transcriptomics, proteomics) and associated drug information have begun reshaping our understanding of multiple sclerosis. However, these data are scattered across numerous references, making them challenging to fully utilize. We manually mined and compiled these data within the Multiple Sclerosis Gene Database (MSGD) database, intending to continue updating it in the future. We screened 5485 publications and constructed the current version of MSGD. MSGD comprises 6255 entries, including 3274 variant entries, 1175 RNA entries, 418 protein entries, 313 knockout entries, 612 drug entries and 463 high-throughput entries. Each entry contains detailed information, such as species, disease type, detailed gene descriptions (such as official gene symbols), and original references. MSGD is freely accessible and provides a user-friendly web interface. Users can easily search for genes of interest, view their expression patterns and detailed information, manage gene sets and submit new MS-gene associations through the platform. The primary principle behind MSGD's design is to provide an exploratory platform, aiming to minimize filtration and interpretation barriers while ensuring highly accessible presentation of data. This initiative is expected to significantly assist researchers in deciphering gene mechanisms and improving the prevention, diagnosis and treatment of MS. Database URL: http://bio-bigdata.hrbmu.edu.cn/MSGD.

Vitamin D receptor gene BsmI (rs1544410) polymorphism: role in multiple sclerosis and genotype-phenotype correlations

BACKGROUND

Multiple sclerosis (MS) has a complex pathophysiology which depends on many endogenous and exogenous factors. Vitamin D involvement has been largely studied in MS. The large distribution of the vitamin D receptor (VDR) in different immune cells is suggestive of an immunomodulatory role. The VDR gene polymorphisms have been proposed as potential risk factors for MS development or evolution with non-conclusive results.

METHODS AND RESULTS

We conducted a cross-sectional study including patients ≥ 18 years, with a diagnosis of relapsing remitting MS according to the McDonald Criteria and having a minimum follow-up period of one year after starting a disease modifying therapy. Two study groups were compared based on the Multiple Sclerosis Severity Scale or MSSS: "a slow progressor" group for an MSSS ≤ 5, and a "fast progressor" group for an MSSS > 5. The rs1544410 VDR gene polymorphism was studied for all patients. Eighty patients were included. The fast progressor groups had a higher EDSS at onset, a higher total number of relapses, more frequent and shorter time to secondary progression. The progression profile was not statistically different between genotypes and alleles of the VDR gene polymorphism rs1544410. The CC genotype and wild-type allele exhibited a more aggressive disease phenotype with a higher number of relapses the first year, shorter time to secondary progression and cerebral atrophy on assessment.

CONCLUSIONS

Our results suggest potential genotype-phenotype correlations for the rs1544410 VDR gene polymorphism in the disease course of MS. Future research on a larger scale is needed to confirm these findings.

The protective role of interaction between vitamin D, sex hormones and calcium in multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder that causes disability and paralysis, especially among young adults. Although interactions of several factors, such as viral infections, autoimmunity, genetic and environmental factors, performance a role in the beginning and progression of the disease, the exact cause of MS is unknown to date. Different immune cells such as Th1 and Th17 play an impressive role in the immunopathogenesis of MS, while, regulatory cells such as Th2 and Treg diminish the severity of the illness. Sex hormones have a vital role in many autoimmune disorders, including multiple sclerosis. Testosterone, estrogen and progesterone have various roles in the progress of MS, which higher prevalence of disease in women and more severe in men reveals the importance of sex hormones' role in this disease. Vitamin D after chemical changes in the body, as an active hormone called calcitriol, plays an important role in regulating immune responses and improves MS by modulating the immune system. The optimum level of calcium in the body with vitamin D modulates immune responses and calcium as an essential ion in the body plays a key role in the treatment of autoimmune diseases. The interaction between vitamin D and sex hormones has protective and therapeutic effects against MS and functional synergy between estrogen and calcitriol occurs in disease recovery. Moreover, vitamin D and calcium interact with each other to regulate the immune system and shift them to anti-inflammatory responses.

Association of vitamin D receptor polymorphisms with vitamin D and calcium levels in Turkish multiple sclerosis patients

Aim: The present study was conducted to assess the impact of gene (vitamin D receptor [VDR] polymorphisms) - environment (serum vitamin D and calcium levels) interaction on multiple sclerosis (MS) risk. Materials & methods: FokI, BsmI, TaqI and ApaI genotyping were performed in 149 MS patients and 127 controls. We measured serum vitamin D and calcium levels. Results: No significant difference between VDR polymorphisms and MS risk was detected. In patients with FokI ff, BsmI Bb, TaqI Tt and ApaI AA genotypes, vitamin D levels were statistically higher. Serum calcium levels were significantly lower in patients with FokI FF, Ff, all BsmI and TaqI genotypes and ApaI AA and Aa genotypes. Conclusion: No significant association was found between VDR polymorphisms with MS risk.

Vitamin D and Genetic Susceptibility to Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease affecting the central nervous system (CNS), resulting from the interaction among genetic, epigenetic, and environmental factors. Vitamin D is a secosteroid, and its circulating levels are influenced by environment and genetics. In the last decades, research data on the association between MS and vitamin D status led to hypothesize a possible role for hypovitaminosis D as a risk factor for MS. Some gene variants encoding proteins involved in vitamin D metabolism, transport, and function, which are responsible for vitamin D status alterations, have been related to MS susceptibility. This review explores the current literature on the influence of vitamin D-related genes in MS susceptibility, reporting all single-nucleotide polymorphisms (SNPs) investigated to date in 12 vitamin D pathway genes. Among all, the gene codifying vitamin D receptor (VDR) is the most studied. The association between VDR SNPs and MS risk has been reported by many Authors, with a few studies producing opposite results. Other vitamin D-related genes (including DHCR7/NADSYN1, CYP2R1, CYP27A1, CYP3A4, CYP27B1, CYP24A1, Megalin-DAB2-Cubilin, FGF-23, and Klotho) have been less investigated and achieved more conflicting evidence. Taken together, findings from the studies reviewed cannot clarify whether and to what extent vitamin D-related gene variants can influence MS risk.

Vitamin D and Multiple Sclerosis: An Open-Ended Story

Multiple Sclerosis (MS) is a chronic inflammatory autoimmune disease of the Central Nervous System (CNS). Genetic, epigenetic and environmental factors interact together, contributing to the complex pathogenesis of the disease. In the last decades, the role of hypovitaminosis D on MS risk was hypothesised. Several factors drive the regulation of vitamin D status, including genetics. The current review summarises the literature evidence on the association between vitamin D and MS, with a focus on the genetic polymorphisms in vitamin D-related genes. The variants of the genes codifying Vitamin D Receptor (VDR), Vitamin D Binding Protein (VDBP) and CYP enzymes have been investigated, but the findings are controversial. Only a few studies have addressed the role of DHCR7 polymorphisms in MS risk.

Association between vitamin D receptor (VDR) polymorphisms and the risk of multiple sclerosis (MS): an updated meta-analysis

Background

The association between the Vitamin D Receptor (VDR) gene polymorphism and the risk of Multiple sclerosis (MS) has been evaluated in several researches. However, the findings were inconsistent and inconclusive. Therefore, we set out a meta-analysis of all eligible published case-control studies to obtain an exact evaluation of the association between VDR gene polymorphisms and MS.

Method

All relevant studies reporting the association between the VDR gene FokI (rs2228570), or/and TaqI (rs731236) or/and BsmI (rs1544410) or/and ApaI (rs7975232) polymorphisms and susceptibility to MS published up to May, 2019 were identified by comprehensive systematic search in the electronic database of web of science, Scopus, and PubMed. After that, the strength of association between VDR gene polymorphisms and susceptibility to MS was evaluated by odds ratio (OR) and 95% confidence interval (CI).

Results

A total of 30 case–control studies were included in the meta-analysis. The overall results suggested a significant association between TaqI polymorphism and MS risk under heterozygote genetic model (OR = 1.27, 95%CI = 1.01–1.59, random effect). Moreover, the pooled results of subgroup analysis declined presence of significant association under all defined genetic model. In subgroup analysis, BsmI polymorphisms was associated with increased risk of MS under recessive model in Asian populations. On the other hand, ApaI polymorphism was associated with decreased risk of MS under recessive and aa vs. AA model in Asian populations.

Conclusion

This meta-analysis suggested a significant association between TaqI polymorphism and MS susceptibility. Furthermore, BsmI polymorphism was associated with increased risk of MS in Asian populations. In contrast, ApaI polymorphism was associated with decreased risk of MS in Asian populations. Future large-scale studies on gene–environment and gene–gene interactions are required to estimate risk factors and assist early diagnosis of patients at high risk for MS.

Association of Vitamin D Receptor Gene Polymorphisms and the Risk of Multiple Sclerosis: A Meta Analysis

BACKGROUND

Previous studies have reported vitamin D receptor (VDR) polymorphisms in multiple sclerosis (MS); however, the results remain contradictory. This study aimed to investigate the association between VDR polymorphisms and the risk of MS.

METHODS

PubMed and Embase databases were searched to obtain eligible studies. Data were calculated by odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

Twenty seven case-control studies with 4879 MS patients and 5402 controls were included. There was no significant association between ApaI polymorphisms and MS in the overall population. In Asians, no association was found between ApaI polymorphism and MS in the recessive, dominant, Codominant (OR1), Codominant (OR2), Codominant (OR3) models and allele contrast. Similar results were obtained between BsmI polymorphisms and MS. The association between TaqI polymorphism and MS showed significance in the recessive, homozygous, codominant (OR3) models in the overall population and Caucasians. The dominant model showed no association of Taq I polymorphism with MS risk in HLA-DRB1*15-positive and HLA-DRB1*15-negative groups. FokI polymorphism with MS was found in Codominant (OR3) model in the overall population. In Asians, FokI polymorphism showed association with MS in recessive, dominant, Codominant (OR1), Codominant (OR3) models and allele contrast. Subgroup analysis of sex showed no associations between TaqI or FokI polymorphism and MS risk in males or females in all models or allele contrast.

CONCLUSIONS

The VDR TaqI polymorphisms showed association with MS risk, especially in Caucasians. In Asians, ApaI and FokI polymorphisms correlated with MS risk, while BsmI polymorphisms showed no association with MS.

Vitamin D receptor gene polymorphisms in multiple sclerosis disease: A case-control study

Multiple sclerosis (MS) is a common neurologic disorder that is a chronic inflammatory, demyelinating, and neurodegenerative disease of the central nervous system (CNS). Its etiology remains unknown. Several recent studies have found that decreased susceptibility to vitamin D deficiency is also associated with a decreased risk of MS. The role of vitamin D receptor (VDR) gene and its polymorphisms are highlighted as susceptible components. In this study, we aimed to identify the relationship between ApaI (rs7975232), BsmI (rs 1544410), and TaqI (rs731236) gene polymorphisms with MS. ApaI, BsmI, and TaqI genotypes were determined in 70 patients with MS and in 70 control subjects. DNA was isolated from blood samples, and then ApaI, BsmI and TaqI gene polymorphisms were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. The distribution of BsmI and TaqI polymorphisms did not show any significant differences in MS patients and controls; however, increased A allele of ApaI polymorphism was found in MS patients. Our findings suggest that the ApaI gene polymorphism might be associated with MS. Investigation of a larger population and functional work on these gene structures and function in MS patients are recommended.

Analysis of Vitamin D Receptor Polymorphisms in Patients with Familial Multiple Sclerosis

Objective

Genetic and environmental factors are important in the development of the multiple sclerosis (MS). Vitamin D shows its effects on the immune system with the vitamin D receptor (VDR) in the nucleus. Single nucleotide polymorphisms (SNPs) in the VDR gene can lead to alterations in vitamin D functions and metabolism.Taq I, Apa I, Fok I and Bsm I polymorphisms and MS associations have been investigated in many studies. VDR gene polymorphism has not been previously studied in patients with familial MS.

Aim

We aimed to investigate the relationship between familial MS patients present in Turkish population and VDR genotypes Taq I, Apa I and Fok I polymorphisms.

Methods

29 patients with a family history of MS and 120 healthy control subjects were included in the present study. We studied present VDR genotypes Taq I, Apa I and Fok I polymorphisms.

Results

We observed a significant difference between controls and patient group only in Taq I polymorphism (p: 0.025). Homozygousity of G allele was not seen in the patients whereas in controls frequency of that genotype was p:0.208. When gender was considered males show significant difference for GG genotype. There were no significant association for the Apa I and Fok I polymorphisms.

Conclusion

Although our findings suggest association between VDR Taq I polymorphism and the familial MS, additional studies are needed to establish detailed relationships.

Regulation of Microbiota by Vitamin D Receptor: A Nuclear Weapon in Metabolic Diseases

Metabolic syndrome is a multi-faceted disease. The microbiota, as a newly discovered organ, contributes to the pathogenesis and progression of metabolic syndrome. Recent studies have demonstrated that nuclear receptors play critical roles in metabolic diseases. In the current review, we discuss the general role of the microbiome in health and metabolic syndrome. We summarize the functions of the nuclear receptor vitamin D receptor (VDR) in metabolism. The focus of this review is the novel roles of vitamin D/VDR signaling in regulating inflammation and the microbiome, especially in obesity. Furthermore, we extend our discussion of potential gut-liver axis mediated by VDR signaling and microbiota in obesity. Finally, we discuss the potential clinical application of probiotics and fecal microbiota transplantation in prevention and treatment of metabolic syndrome. Insights into nuclear receptors in metabolism and metabolic diseases will allow us to develop new strategies for fighting metabolic diseases.

Ancient Nuclear Receptor VDR With New Functions: Microbiome and Inflammation

The biological functions of 1α,25-dihydroxyvitamin D3 are regulated by nuclear receptor vitamin D receptor (VDR). The expression level of VDR is high in intestine. VDR is an essential regulator of intestinal cell proliferation, barrier function, and immunity. Vitamin D/VDR plays a protective role in inflammatory bowel diseases (IBDs), both ulcerative colitis and Crohn's disease. Emerging evidence demonstrates low VDR expression and dysfunction of vitamin D/VDR signaling in patients with IBD. Here, we summarize the progress made in vitamin D/VDR signaling in genetic regulation, immunity, and the microbiome in IBD. We cover the mechanisms of intestinal VDR in regulating inflammation through inhibiting the NF-ĸB pathway and activating autophagy. Recent studies suggest that the association of VDR single nucleotide polymorphisms with immune and intestinal pathology may be sex dependent. We emphasize the tissue specificity of VDR and its sex- and time-dependent effects. Furthermore, we discuss potential clinical application and future direction of vitamin D/VDR in preventing and treating IBD.

Role of gene polymorphisms in vitamin D metabolism and in multiple sclerosis

Multiple sclerosis (MS) is a complex inflammatory disease of the central nervous system (CNS) resulting in neurological impairment and disability. There is evidence that adequate vitamin D levels may lower the risk of MS development. The aetiology of MS is complex and involves both genetic and environmental factors. In fact, not one but several genes are believed to lead to the disease. As for environmental factors, one of the most important risk factors is vitamin D deficiency, which, in turn, is closely related to gene polymorphisms that play a role in vitamin D metabolism and regulation. However, information about these gene polymorphisms is quite contradictory. The aim of this review is to discuss the association between some of the vitamin D-related gene variants and MS.

The Impact of Five VDR Polymorphisms on Multiple Sclerosis Risk and Progression: a Case-Control and Genotype-Phenotype Study

Vitamin D receptor polymorphisms have been the target of many studies focusing on multiple sclerosis. However, previously reported results have been inconclusive. The objective of this study was to investigate the association between five vitamin D receptor polymorphisms (EcoRV, FokI, ApaI, TaqI, and BsmI) and multiple sclerosis susceptibility and its course. The study was carried out as a case-control and genotype-phenotype study, consisted of 296 Czech multiple sclerosis patients and 135 healthy controls. Genotyping was carried out using polymerase chain reaction and restriction analysis. In multiple sclerosis men, allele and/or genotype distributions differed in EcoRV, TaqI, BsmI, and ApaI polymorphisms as compared to controls (EcoRV, p_a = 0.02; Taq, p_g = 0.02, p_a = 0.02; BsmI, p_g = 0.02, p_a = 0.04; ApaI, p_g = 0.008, p_a = 0.005). In multiple sclerosis women, differences in the frequency of alleles and genotypes were found to be significant in ApaI (controls vs multiple sclerosis women: p_g = 0.01, p_a = 0.05). Conclusive results were observed between multiple sclerosis women in the case of EcoRV [differences in Expanded Disability Status Scale (p = 0.05); CT genotype was found to increase the risk of primary progressive multiple sclerosis 5.5 times (CT vs CC+TT p_corr = 0.01, sensitivity 0.833, specificity 0.525, power test 0.823)] and FokI [borderline difference in Multiple Sclerosis Severity Score (p = 0.05)]. Our results indicate that the distribution of investigated vitamin D receptor polymorphisms is a risk factor for multiple sclerosis susceptibility and progression in the Czech population. The association between disease risk and polymorphisms was found to be stronger in men. The association of disease progression with polymorphisms was observed only in women.

The association between vitamin D receptor polymorphisms and multiple sclerosis in a Turkish population

BACKGROUND

Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system (CNS). Genetic and environmental factors are important in disease development. Many studies have investigated the relationship between MS and VDR polymorphisms. VDR gene polymorphism has not been previously studied in Turkish MS patients. We aimed to investigate the relationship between MS and VDR genotypes Taq I, Apa I and Fok I polymorphisms in a Turkish population.

METHODS

167 MS patients and 146 healthy control subjects were included in the present study. MS and the VDR TaqI (rs731236), ApaI (rs7975232), and FokI (rs2228570) polymorphisms were investigated.

RESULTS

The study enrolled 167 patients (121 females, 46 males) with MS and 146 healthy individuals (88 females, 58 males). The frequency of only the Fok I polymorphism differed significantly between the two groups (p = 0.002). The TaqI (rs731236) and ApaI (rs7975232) genotype distributions were not significantly different between MS patients and healthy controls (p = 0.626 and p = 0.990, respectively). Also there were no significant gender difference between patients and controls for Taq I and Apa I.

CONCLUSION

In conclusion, we found a significant association between MS and the FokI polymorphism in our region of Turkey. However, the results may be different in other populations. More epidemiological and genetic studies are needed to explain the association between genetic factors and MS.

Association between Single Nucleotide Polymorphisms in Vitamin D Receptor Gene Polymorphisms and Permanent Tooth Caries Susceptibility to Permanent Tooth Caries in Chinese Adolescent

Purpose

Dental caries is a multifactorial infectious disease. In this study, we investigated whether single nucleotide polymorphisms (SNPs) in vitamin D receptor (VDR) gene were associated with susceptibility to permanent tooth caries in Chinese adolescents.

Method

A total of 200 dental caries patients and 200 healthy controls aged 12 years were genotyped for VDR gene polymorphisms using the PCR-restriction fragment length polymorphism (PCR-RFLP) assay. All of them were examined for their oral and dental status with the WHO criteria, and clinical information such as the Decayed Missing Filled Teeth Index (DMFT) was evaluated. Genomic DNA was extracted from the buccal epithelial cells. The four polymorphic SNPs (Bsm I, Taq I, Apa I, and Fok I) in VDR were assessed for both genotypic and phenotypic susceptibilities.

Results

Among the four examined VDR gene polymorphisms, the increased frequency of the CT and CC genotype of the Fok I VDR gene polymorphism was associated with dental caries in 12-year-old adolescent, compared with the controls (X² = 17.813, p ≤ 0.001). Moreover, Fok I polymorphic allele C frequency was significantly increased in the dental caries cases, compared to the controls (X² = 14.144, p ≤ 0.001, OR = 1.730, 95% CI = 1.299–2.303). However, the other three VDR gene polymorphisms (Bsm I, Taq I, and Apa I) showed no statistically significant differences in the caries groups compared with the controls.

Conclusion

VDR-Fok I gene polymorphisms may be associated with susceptibility to permanent tooth caries in Chinese adolescent.

Vitamin D receptor gene polymorphisms are associated with multiple sclerosis in Mexican adults

BACKGROUND

Multiple sclerosis (MS) is the most prevalent autoimmune inflammatory demyelinating disease of the central nervous system (CNS) in young adults. More than 50 genomic regions have been associated with MS susceptibility. Due the important immune-modulating properties of Vitamin D, Vitamin D receptor (VDR) gene polymorphisms - which interfere with the actions of Vitamin D- could be related to increased risk of MS.

METHODS

We studied 120 patients fulfilling the McDonald criteria for MS (81 females and 39 males) and 180 healthy unrelated controls, nested in a case-Control study, and were recruited from the National Institute of Neurology and Neurosurgery, Manuel Velasco Suárez in Mexico City. Genotyping of VDR gene polymorphisms BsmI (rs1544410) and TaqI (rs731236) was performed using TaqMan SNP Genotyping Assay which consists of a predesigned mix of unlabeled polymerase chain reaction (PCR) primers and the TaqMan minor groove binding group (MGB) probe (FAM dye-labeled).

RESULTS

There was a statistically significant, positive association between MS and the T/T genotype of BsmI polymorphism (OR=4.15; 95%CI 1.83-9.39), showing also a significant positive trend across genotypes (p<0.01). This association was also present evaluating the recessive inheritance model of the polymorphism (OR=3.91; 95%CI 1.77-8.64). When evaluating the association by alleles, the statistically significant positive association seen by genotypes was confirmed in the T allele carriers, showing an OR of 1.83 (95%CI 1.27-2.65) for MS.

CONCLUSIONS

We found a positive association of the genetic VDR polymorphisms TaqI (rs731236) and BsmI (rs1544410), with the risk of MS in a sample of Mexican adults.

Analysis of Associations of Human BAFF Gene Polymorphisms with Autoimmune Thyroid Diseases

Background

The B-lymphocyte-activating factor (BAFF) is associated with B-cell functions, and gene polymorphisms of the BAFF have been linked to autoimmune diseases (AIDs). In this study, we explored possible associations of two BAFF single-nucleotide polymorphisms (SNPs), rs1041569 and rs2893321, with autoimmune thyroid diseases (AITDs) in an ethnic Chinese population.

Material and Methods

In total, 319 Graves’ disease (GD), 83 Hashimoto’s thyroiditis (HT) patients, and 369 healthy controls were enrolled. Polymerase chain reaction-restriction fragment length polymorphism and direct sequencing were used to genotype rs2893321 and rs1041569.

Results

There was a significant difference in frequencies of the G allele and AG+GG genotype of rs2893321 between the GD and control groups (p = 0.013, odds ratio (OR) = 0.76, and p = 0.017, OR = 0.68, respectively) and between the AITD and control groups (p = 0.009, OR = 0.76, and, p = 0.014, OR = 0.69, respectively). The AA genotype of rs2893321 was associated with low titers of the thyroid-stimulating hormone receptor antibody (TSHRAb) (p = 0.015) in males but not in females. The AA genotype of rs2893321 was associated with the presence of two different types of thyroid autoantibody (TAb) (TSHRAb and Hashimoto’s autoantibody (anti-thyroglobulin or anti-microsomal antibody)) in females and with that of one type in males.

Conclusions

rs2893321 may be a susceptible genetic variant for the development of GD and AITDs. Associations of rs2893321 with susceptibility to GD and AITDs and the correlation between rs2893321 and TAb exhibit a dimorphic pattern. Additional studies with larger sample sizes are required to confirm our findings.

The Association of Vitamin D Receptor Polymorphisms with Multiple Sclerosis in a Case-Control Study from Kuwait

Vitamin D deficiency is associated with several diseases including multiple sclerosis (MS). Several factors influence vitamin D levels and its optimal multi-function maintenance. Our objective was to assess quantifiable variables influencing vitamin D level and metabolism in MS patients from Kuwait. In a case-control study involving 50 MS patients, and 50 healthy control individuals for which plasma vitamin D levels, supplement use, vitamin D receptor (VDR) variants, and skin pigmentation indices were ascertained; we found overall vitamin D levels to be deficient in both groups, and supplement use to be common practice. VDR variants TaqI and BsmI associated with MS risk, and ApaI associated with low disease progression. VDR variant FokI associated with higher vitamin D levels in both groups. We conclude that several quantifiable variables related to vitamin D associate with MS suggesting a possible clinical immuno-modulatory application of vitamin D for MS patients in Kuwait.