Single nucleotide polymorphisms in the vitamin D pathway associating with circulating concentrations of vitamin D metabolites and non-skeletal health outcomes: Review of genetic association studies

Causal association between serum 25-Hydroxyvitamin D levels and cutaneous melanoma: a two-sample Mendelian randomization study

Background

Despite numerous observational studies on the association between serum 25-Hydroxyvitamin D levels and cutaneous melanoma, causal inferences remain ambiguous due to confounding and reverse causality. This study aimed to elucidate the causal relationship between serum 25-Hydroxyvitamin D levels and melanoma incidence using Mendelian randomization (MR).

Methods

A two-sample MR was conducted using genetic variants associated with serum 25-Hydroxyvitamin D levels as instrumental variables. Summary statistics for these variants were derived from genome-wide association studies, and those for melanoma risk were obtained from a comprehensive melanoma case-control study. Robustness of the results was assessed through sensitivity analyses, including the "leave-one-out" approach and tests for potential pleiotropy.

Results

The MR analysis provided substantial evidence of a positive causal relationship between serum 25-Hydroxyvitamin D levels and the incidence of cutaneous melanoma, suggesting that each unit increase in serum 25-Hydroxyvitamin D levels corresponds with an increased risk of melanoma. Tests for pleiotropy showed minimal effects, and the sensitivity analysis confirmed no disproportionate influence by any individual single nucleotide polymorphism (SNP).

Conclusion

The findings indicated a potentially causal positive association between serum 25-Hydroxyvitamin D levels and melanoma risk, challenging traditional beliefs about vitamin D's role in melanoma. This emphasizes the need for a balanced and personalized approach to vitamin D supplementation and sun exposure, particularly in high-risk populations. These results should be interpreted with caution due to potential unrecognized pleiotropy and confounding factors. Future research should focus on validating these findings in diverse populations and exploring underlying biological mechanisms.

A Mathematical Model for Determining the Body's Fluctuating Need for and Synthesis of Active Vitamin D

The process by which 1,25(OH)₂D₃ is synthesized and degraded and how it is transported out of the cell and body is described. The changing demand for the synthesis of 1-25(OH)₂D₃ during different conditions experienced by the body is reviewed. A method of determining 1,25(OH)₂D₃ synthesis and demand, and the percent utilization of 25(OH)D₃ to make 1,25(OH)₂D₃ is presented based on the measurement of the end metabolites of 1,25(OH)₂D₃ and of its immediate precursor, 25(OH)D₃. A mathematical model has been developed to allow the calculation of 1,25(OH)₂ D synthesis, and demand, and the percent utilization of 25(OH)D₃. Simple algebraic equations have been derived which allow the calculation of these new parameters using the concentrations of the end metabolites of 1,25(OH)₂D₃ and its immediate precursor, 25(OH)D₃ in the serum and urine. Vitamin D plays an important role in combating invading bacteria and viruses and in subduing the body's associated inflammatory response. This new approach to evaluating vitamin D status may help clinicians determine 25(OH)D₃ and 1,25(OH)₂D₃ levels needed to suppress bacterial infections, viral replication during new viral infections and the reactivation of latent viruses, and to downregulate the inflammatory responses caused by bacteria and viruses.

Association of CYP2R1 and VDR Polymorphisms with Metabolic Syndrome Components in Non-Diabetic Brazilian Adolescents

Associations between vitamin D deficiency and metabolic syndrome (MS) have been reported; however, the underlying biological mechanisms remain controversial. The aim of this study was to investigate the associations of CYP2R1 and VDR variants with MS and MS components in non-diabetic Brazilian adolescents. This cross-sectional study included 174 adolescents who were classified as overweight/obese. Three CYP2R1 variants and four VDR variants were identified by allelic discrimination. The CYP2R1 polymorphisms, rs12794714 (GG genotype) (odds ratio [OR] = 3.54, 95% confidence interval [CI] = 1.24–10.14, p = 0.023) and rs10741657 (recessive model—GG genotype) (OR = 3.90, 95%CI = 1.18–12.92, p = 0.026) were significantly associated with an increased risk of MS and hyperglycemia, respectively. The AG + GG genotype (dominant model) of the rs2060793 CYP2R1 polymorphism was associated with hyperglycemia protection (OR = 0.28, 95%CI = 0.08–0.92, p = 0.037). Furthermore, the CC genotype (recessive model) of the rs7975232 VDR polymorphism was significantly associated with a risk of hypertension (OR = 5.91, 95%CI = 1.91–18.32, p = 0.002). In conclusion, the CYP2R1 rs12794714 polymorphism could be considered a possible new molecular marker for predicting the risk of MS; CYP2R1 rs10741657 polymorphism and VDR rs7975232 polymorphism are associated with an increased risk of diabetes and hypertension in adolescents with overweight/obesity.

Vitamin D and musculoskeletal health: outstanding aspects to be considered in the light of current evidence

Vitamin D enhances calcium absorption and bone mineralisation, promotes maintenance of muscle function, and is crucial for musculoskeletal health. Low vitamin D status triggers secondary hyperparathyroidism, increases bone loss, and leads to muscle weakness. The primary physiologic function of vitamin D and its metabolites is maintaining calcium homeostasis for metabolic functioning, signal transduction, and neuromuscular activity. A considerable amount of human evidence supports the well-recognised contribution of adequate serum 25-hydroxyvitamin D concentrations for bone homeostasis maintenance and prevention and treatment strategies for osteoporosis when combined with adequate calcium intake. This paper aimed to review the literature published, mainly in the last 20 years, on the effect of vitamin D and its supplementation for musculoskeletal health in order to identify the aspects that remain unclear or controversial and therefore require further investigation and debate. There is a clear need for consistent data to establish realistic and meaningful recommendations of vitamin D status that consider different population groups and locations. Moreover, there is still a lack of consensus on thresholds for vitamin D deficiency and optimal status as well as toxicity, optimal intake of vitamin D, vitamin D supplement alone as a strategy to prevent fractures and falls, recommended sun exposure at different latitudes and for different skin pigmentations, and the extra skeletal effects of vitamin D.

Genetic control of serum 25(OH)D levels and its association with ethnicity

BACKGROUND

Identified DNA variants associated with serum 25-hydroxyvitamin vitamin D (25[OH]D) concentration may provide mechanistic insights into the vitamin D metabolic pathway in individuals. Our aim was to further characterise participants and their serum 25(OH)D concentration at baseline using candidate single nucleotide polymorphism (SNP) genotyping.

METHODS

5110 participants, aged 50-84 years, were recruited from the community. Blood samples were collected at baseline to measure serum 25(OH)D by liquid chromatography mass spectrometry and the participants were genotyped for four markers close to or within genes in the vitamin D metabolic pathway known to be associated with differences in 25(OH)D. The markers and their associated genes were rs12785878 (DHCR7), rs10741657 (CYP2R1), rs4588 (DBP) and rs2228570 (VDR).

RESULTS

All four markers had significantly different genotype distributions and minor allele frequencies between the four self-determined ethnicities (European/Other, Māori, Pacific, and South Asian). For example, the frequency in each ethnic group of the G allele for the marker rs12785878 was 0.26, 0.71, 0.89, and 0.78 respectively. Using multivariable regression in the full cohort, three out of four markers were significantly associated with baseline concentrations of 25(OH)D (mean differences: 2.9-10.9 nmol/L). Collectively, the four markers explained 8.4% of the variation in 25(OH)D concentrations.

CONCLUSION

Significant ethnic variations exist in the distribution of alleles associated with serum 25(OH)D concentration, particularly rs12785878, in a multi-ethnic community sample from New Zealand.

Vitamin D3 promotes longevity in Caenorhabditis elegans

Vitamin D deficiency is associated with a variety of age-related diseases and is becoming increasingly more prevalent in the population over time. Some diseases associated with deficiency are cardiovascular disease, cancer, and neurodegeneration. This association, as well as the fact that vitamin D has been demonstrated to play an important role in a variety of extraskeletal processes, has led some to claim that vitamin D is an essential longevity vitamin. However, the role of vitamin D in healthy aging has been difficult to determine. In order to study vitamin D in the context of aging, the model organism, Caenorhabditis elegans (C. elegans), was employed. To study vitamin D's impact on aging and age-related disease, lifespan and health span were measured across three different genetic strains of C. elegans. Strains investigated were wildtype (N2), worms with a mutant vitamin D receptor ortholog (nhr-8), and worms engineered to represent Alzheimer disease (gnals2). Bioinformatic analysis of available public data was also performed in order to identify the transcriptional response produced in N2 worms treated with vitamin D₃. Treatment with vitamin D₃ significantly extended the lifespan of N2 worms and rescued nhr-8 worms, which typically have decreased lifespans compared to N2. Treatment with vitamin D₃ minimally extended the lifespan of gnals2 worms. Similar results were obtained for measures of health span, quantified as motility through time. Differentially expressed genes upon treatment with vitamin D₃ were largely associated with biological processes such as the innate immune response and metabolism of xenobiotic compounds in the worms, which may explain the observed increase in lifespan and health span.

Lack of association between CYP27B1 gene polymorphism and type 2 diabetes mellitus in Iranian patients

Purpose

Type 2 diabetes mellitus (T2DM) is a global health problem with multiple etiological factors. Previous studies indicated that 1- alpha, 25-dihydroxyvitamin D3, a molecule that is produced by CYP27B1, could protect insulin-secreted cells from destruction by immune cells. The aim of the study was to investigate the CYP27B1 promoter gene polymorphism in T2DM.

Methods

Two hundred subjects including 100 T2DM and 100 healthy individuals were recruited in the study. ARMS-PCR technique was used to identify rs10877012 genotypes in the 5' region of CYP27B1.

Results

The frequency of CC, CA, and AA genotype was 61/50, 31/39, and 8/11, respectively in T2DM patients compared to healthy subjects. There was no significant difference between both groups in regarding to genotype and allele distribution (P > 0.05). CA (RR = 1.535, 95% CI = 0.841- 2.802) and AA (1.677, 95% CI = 0.627-4.490) genotypes had no association with increased risk of T2DM. In addition, CA + AA versus CC showed no increased risk for T2DM (RR = 0.639, 95% CI = 0.365-1.121).

Conclusion

We found no association between rs10877012 polymorphism and T2DM. There was no increased risk of this polymorphism in T2DM. Further studies with large groups are suggested in other populations to better understand the relation of CYP27B1 gene variation, especially its ethnicity-dependent relation with T2DM.

Vitamin D receptor gene polymorphism and vitamin D supplementation on clinical/ treatment outcome in tuberculosis: current and future perspectives

INTRODUCTION

Tuberculosis (TB) is a transnational public health concern, which requires more precise treatment strategies than the existing approaches. Vitamin D modulates the inflammatory and immune response to the disease. Robust evidence shows that vitamin D deficiency and its receptor gene polymorphism influence the susceptibility to TB and the outcome of the anti-tubercular treatment (ATT). However, in the different populations, these findings were inconsistent and even contradictory.

AREAS COVERED

The current review focuses on the association between vitamin D receptor (VDR) gene polymorphism with the risk of development of TB disease and response to the ATT. Additionally, it reviews various systematic reviews and meta-analyses on the impact of vitamin D supplements on both clinical and treatment outcomes in TB patients.

EXPERT OPINION

Although the majority of the findings rule out the benefits of the supplementation, sufficient evidence is available to warrant larger epidemiological research that should be aimed to generate possible interaction among the VDR polymorphism, vitamin D status, and the outcome in TB. We conclude that establishing such an association in different ethnic populations will help design nutrigenomics- or pharmacogenomics-based vitamin D supplementation to develop a personalized medicine approach to flatten the curve of TB disease.

25(OH)Vitamin D Deficiency and Calcifediol Treatment in Pediatrics

Vitamin D is essential for the normal mineralization of bones during childhood. Although diet and adequate sun exposure should provide enough of this nutrient, there is a high prevalence of vitamin D deficiency rickets worldwide. Children with certain conditions that lead to decreased vitamin D production and/or absorption are at the greatest risk of nutritional rickets. In addition, several rare genetic alterations are also associated with severe forms of vitamin-D-resistant or -dependent rickets. Although vitamin D3 is the threshold nutrient for the vitamin D endocrine system (VDES), direct measurement of circulating vitamin D3 itself is not a good marker of the nutritional status of the system. Calcifediol (or 25(OH)D) serum levels are used to assess VDES status. While there is no clear consensus among the different scientific associations on calcifediol status, many clinical trials have demonstrated the benefit of ensuring normal 25(OH)D serum levels and calcium intake for the prevention or treatment of nutritional rickets in childhood. Therefore, during the first year of life, infants should receive vitamin D treatment with at least 400 IU/day. In addition, a diet should ensure a normal calcium intake. Healthy lifestyle habits to prevent vitamin D deficiency should be encouraged during childhood. In children who develop clinical signs of rickets, adequate treatment with vitamin D and calcium should be guaranteed. Children with additional risk factors for 25(OH)D deficiency and nutritional rickets should be assessed periodically and treated promptly to prevent further bone damage.

Shedding Light on Autophagy During Human Tuberculosis. A Long Way to Go

Immunity against Mycobacterium tuberculosis (Mtb) is highly complex, and the outcome of the infection depends on the role of several immune mediators with particular temporal dynamics on the host microenvironment. Autophagy is a central homeostatic mechanism that plays a role on immunity against intracellular pathogens, including Mtb. Enhanced autophagy in macrophages mediates elimination of intracellular Mtb through lytic and antimicrobial properties only found in autolysosomes. Additionally, it has been demonstrated that standard anti-tuberculosis chemotherapy depends on host autophagy to coordinate successful antimicrobial responses to mycobacteria. Notably, autophagy constitutes an anti-inflammatory mechanism that protects against endomembrane damage triggered by several endogenous components or infectious agents and precludes excessive inflammation. It has also been reported that autophagy can be modulated by cytokines and other immunological signals. Most of the studies on autophagy as a defense mechanism against Mycobacterium have been performed using murine models or human cell lines. However, very limited information exists about the autophagic response in cells from tuberculosis patients. Herein, we review studies that face the autophagy process in tuberculosis patients as a component of the immune response of the human host against an intracellular microorganism such as Mtb. Interestingly, these findings might contribute to recognize new targets for the development of novel therapeutic tools to combat Mtb. Actually, either as a potential successful vaccine or a complementary immunotherapy, efforts are needed to further elucidate the role of autophagy during the immune response of the human host, which will allow to achieve protective and therapeutic benefits in human tuberculosis.

Interplay between Maternal and Neonatal Vitamin D Deficiency and Vitamin-D-Related Gene Polymorphism with Neonatal Birth Anthropometry

Vitamin D deficiency during pregnancy has been associated with poor foetal growth and neonatal birth anthropometry. However, the associations were inconsistent and could be confounded by neonatal vitamin D status and genetic factors. Until recently, limited studies have concomitantly examined the effect of maternal and neonatal vitamin D deficiency and vitamin D-related single nucleotide polymorphisms (SNPs) on neonatal birth anthropometry. This study aims to examine the independent and combined effects of maternal and neonatal vitamin D deficiency and vitamin-D-related SNPs on neonatal birth anthropometry. This cross-sectional study included 217 mother−neonate dyads recruited from Hospital Serdang, Selangor, Malaysia, between 2015 and 2017. Plasma 25-hydroxyvitamin D (25OHD) concentration was measured in maternal and umbilical cord blood using ultra-high-performance liquid chromatography (UHPLC). Maternal and neonatal vitamin D Receptor (VDR) SNP (rs2228570) genotypes were determined using high-resolution melting (HRM). Group-specific component (GC) SNPs (rs4588 and rs7041) genotypes were determined using restriction fragment length polymorphism. Our results showed that: (1) maternal vitamin D deficiency (25OHD < 30 nmol/L) was inversely associated with birth weight, head circumference and crown−heel length; (2) neonatal SNPs, VDR rs2228570 and GC rs4588, were significantly associated with birth weight and head circumference, respectively; and (3) a potential interaction was observed between maternal VDR rs2228570 with maternal vitamin D deficiency on head circumference. These findings suggest that the underlying mechanisms of vitamin D on foetal growth are likely to be localised in the maternal compartment, mediated through the placenta, rather than through cellular mechanisms within the foetus. Further large-scale studies are warranted to validate and extend these findings.

DBP rs7041 and DHCR7 rs3829251 are Linked to CD4+ Recovery in HIV Patients on Antiretroviral Therapy

Background: The lack of the recovery of CD4⁺ T-cells (CD4⁺ recovery) among immunodeficiency virus (HIV)-infected patients on antiretroviral therapy (ART) is not well known. We aimed to analyze the association between single nucleotide polymorphisms (SNPs) underlying vitamin D metabolism and the CD4⁺ recovery in naïve HIV-infected patients who started ART with low baseline CD4⁺.

Methods: We conducted a retrospective study in 411 naïve individuals with plasma HIV load >200 copies/mL and CD4⁺ <200 cells/mm³. During 24 months of follow-up, all patients had plasma HIV load <50 copies/mL. DNA genotyping was performed using the Sequenom MassARRAY platform. The outcome variable was the change in CD4⁺ during the study.

Results: CD4⁺ recovery was higher in patients carrying DBP rs7041 AA genotype (AA versus CC/AC) and DHCR7 rs3829251 AA genotype (AA versus GG/AG) (p-value < 0.05). DBP rs7041 AA genotype was linked to increase in CD4⁺ (adjusted arithmetic mean ratio (aAMR) = 1.22; q-value = 0.011), increase in CD4⁺ ≥P75th [adjusted odds ratio (aOR) = 2.31; q-value = 0.005], slope of CD4⁺ recovery (aAMR = 1.25; q-value = 0.008), slope of CD4⁺ recovery ≥ P75th (aOR = 2.55; q-value = 0.005) and achievement of CD4⁺ ≥500 cells/mm³ (aOR = 1.89; q-value = 0.023). Besides, DHCR7 rs3829251 AA genotype was related to increase in CD4⁺ (aAMR = 1.43; q-value = 0.031), increase in CD4⁺ ≥P75th (aOR = 3.92; q-value = 0.030), slope of CD4⁺ recovery (aAMR = 1.40; q-value = 0.036), slope of CD4⁺ recovery ≥ P75th (aOR = 3.42; q-value = 0.031) and achievement of CD4⁺ ≥500 cells/mm³ (aOR = 5.68; q-value = 0.015).

Conclusion: In summary, DHCR7 rs3829251 and DBP rs7041 polymorphisms were associated with CD4⁺ recovery in HIV-infected patients who started cART with low CD4⁺ T-cell counts.

The role of vitamin D deficiency and elevated inflammatory biomarkers as risk factors for the progression of diabetic nephropathy in patients with type 2 diabetes mellitus

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. Albuminuria is the most sensitive marker for the early recognition of DN. Therefore, we aimed to study the risk factors of albuminuria as a marker of DN among diabetic patients. The study included 41 patients with type 2 diabetes mellitus (T2DM), 50 type 2 diabetic nephropathy (T2DN) patients with macroalbuminuria, 43 T2DN patients with microalbuminuria and 38 healthy controls. Logistic regression was used to detect the most significant risk factors for albuminuria. A high statistically significant difference was found between the groups regarding age, sex, body mass index (BMI), diabetes mellitus (DM) duration, glucose, glycated haemoglobin (HbA1c), creatinine, glomerular filtration rate (GFR), lipid profile, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), the albumin–creatinine ratio (ACR), vitamin D, total parathyroid hormone (PTH), urea, total calcium and chemerin (p < 0.001). It was found that the duration of DM, BMI, glucose, GFR, total cholesterol (TC), low-density lipoprotein (LDL), TNF-α, IL-6, CRP, ACR, vitamin D, PTH and chemerin are significant albuminuria risk factors in DN. Vitamin D deficiency and associated inflammatory mediators such as chemerin, TNF-α, IL-6 and CRP are the most essential risk factors for albuminuria in T2DM patients.

The impact of vitamin D level on serum lipids in type 2 diabetes mellitus

Background: Vitamin D is considered an important regulator of many metabolic processes in the body. Its deficiency was reported to associate with many pathological conditions, with contradicting reports on its role in dyslipidemia. Objectives: To evaluate the role of vitamin D (total and/or free) in improving dyslipidemia of type 2 diabetes mellitus (T2DM). Methods: Sixty-four patients with T2DM, and 73 apparently healthy normal subjects were enrolled in the study from March to October 2020. Their fasting blood glucose, glycated hemoglobin, HbA1c, and serum lipids (cholesterol, its fractions and triglycerides) were measured in addition to total and free vitamin D. Results: There was a significant negative correlation between total vitamin D and each of cholesterol and LDL-C in the diabetic group. The correlations between serum vitamin D and all other lipid parameters (HDL-C, VLDL-C and triglycerides) were non-significant in the diabetic group, while in the control groups none of serum lipids showed significant correlations with vitamin D. Conclusions: The significant negative association of vitamin D with total cholesterol and LDLC in the diabetics reveals the important action of vitamin D in reducing the atherogenic indices, and consequent reduction in the rate of atherosclerosis and cardiovascular disease or stroke.

Genetic Polymorphism of Vitamin D Family Genes CYP2R1, CYP24A1, and CYP27B1 Are Associated With a High Risk of Non-alcoholic Fatty Liver Disease: A Case-Control Study

Background

Previous studies have highlighted the important role of vitamin D and calcium pathway genes in immune modulation, cell differentiation and proliferation, and inflammation regulation, all closely implicated in the pathogenesis of non-alcoholic fatty liver disease (NAFLD).

Objective

This study aims to investigate whether 11 candidate single nucleotide polymorphisms (SNPs) in vitamin D and calcium pathway genes (CYP2R1, CYP24A1, and CYP27B1) are associated with the risk of NAFLD.

Methods

In this case-control study, a total of 3,023 subjects were enrolled, including 1,114 NAFLD cases and 1,909 controls. Eleven genetic variants in CYP2R1, CYP24A1, and CYP27B1 genes were genotyped. Logistic regression analysis was used to assess the effects of these variants on NAFLD risk. The functional annotations of positive SNPs were further evaluated by bioinformatics analysis.

Results

After adjusting for age, gender, and metabolic measures, we identified that CYP24A1 rs2296241 variant genotypes (recessive model: OR, 1.316; 95% CI, 1.048–1.653; p = 0.018), rs2248359 variant genotypes (recessive model: OR, 1.315; 95% CI, 1.033–1.674; p = 0.026), and CYP27B1 rs4646536 variant genotypes (additive model: OR, 1.147; 95% CI, 1.005–1.310; p = 0.042) were associated with an elevated risk of NAFLD. In combined effects analysis, we found that NAFLD risk significantly increased among patients carrying more rs2296241-A, rs2248359-T, and rs4646536-T alleles (p_trend = 0.049). Multivariate stepwise analysis indicated that age, visceral obesity, ALT, γ-GT, hypertriglyceridemia, hypertension, low HDL-C, hyperglycemia, and unfavorable alleles were independent predictors of NAFLD (all p < 0.05). The area under the receiver operating characteristic curve was 0.789 for all the above factors.

Conclusion

The polymorphisms of vitamin family genes CYP24A1 (rs2296241, CYP24A1, and rs2248359) and CYP27B1 (rs4646536) were associated with NAFLD risk in Chinese Han population, which might provide new insight into NAFLD pathogenesis and tools for screening high-risk population.

Association between Polymorphisms in Vitamin D Pathway-Related Genes, Vitamin D Status, Muscle Mass and Function: A Systematic Review

An association between vitamin D level and muscle-related traits has been frequently reported. Vitamin D level is dependent on various factors such as sunlight exposure and nutrition. But also on genetic factors. We, therefore, hypothesize that single nucleotide polymorphisms (SNPs) within the vitamin D pathway-related genes could contribute to muscle mass and function via an impact on vitamin D level. However, the integration of studies investigating these issues is still missing. Therefore, this review aimed to systematically identify and summarize the available evidence on the association between SNPs within vitamin D pathway-related genes and vitamin D status as well as various muscle traits in healthy adults. The review has been registered on PROSPERO and was conducted following PRISMA guidelines. In total, 77 studies investigating 497 SNPs in 13 different genes were included, with significant associations being reported for 59 different SNPs. Variations in GC, CYP2R1, VDR, and CYP24A1 genes were reported most frequently, whereby especially SNPs in the GC (rs2282679, rs4588, rs1155563, rs7041) and CYP2R1 genes (rs10741657, rs10766197, rs2060793) were confirmed to be associated with vitamin D level in more than 50% of the respective studies. Various muscle traits have been investigated only in relation to four different vitamin D receptor (VDR) polymorphisms (rs7975232, rs2228570, rs1544410, and rs731236). Interestingly, all of them showed only very low confirmation rates (6-17% of the studies). In conclusion, this systematic review presents one of the most comprehensive updates of the association of SNPs in vitamin D pathway-related genes with vitamin D status and muscle traits in healthy adults. It might be used for selecting candidate SNPs for further studies, but also for personalized strategies in identifying individuals at risk for vitamin D deficiency and eventually for determining a potential response to vitamin D supplementation.

A 12 kb multi-allelic copy number variation encompassing a GC gene enhancer is associated with mastitis resistance in dairy cattle

Clinical mastitis (CM) is an inflammatory disease occurring in the mammary glands of lactating cows. CM is under genetic control, and a prominent CM resistance QTL located on chromosome 6 was reported in various dairy cattle breeds. Nevertheless, the biological mechanism underpinning this QTL has been lacking. Herein, we mapped, fine-mapped, and discovered the putative causal variant underlying this CM resistance QTL in the Dutch dairy cattle population. We identified a ~12 kb multi-allelic copy number variant (CNV), that is in perfect linkage disequilibrium with a lead SNP, as a promising candidate variant. By implementing a fine-mapping and through expression QTL mapping, we showed that the group-specific component gene (GC), a gene encoding a vitamin D binding protein, is an excellent candidate causal gene for the QTL. The multiplicated alleles are associated with increased GC expression and low CM resistance. Ample evidence from functional genomics data supports the presence of an enhancer within this CNV, which would exert cis-regulatory effect on GC. We observed that strong positive selection swept the region near the CNV, and haplotypes associated with the multiplicated allele were strongly selected for. Moreover, the multiplicated allele showed pleiotropic effects for increased milk yield and reduced fertility, hinting that a shared underlying biology for these effects may revolve around the vitamin D pathway. These findings together suggest a putative causal variant of a CM resistance QTL, where a cis-regulatory element located within a CNV can alter gene expression and affect multiple economically important traits.

Association of the polymorphism of the vitamin D receptor gene (VDR) with the risk of leprosy in the Brazilian Amazon

The transmission and evolution of leprosy depends on several aspects, including immunological and genetic factors of the host, as well as genetic factors of Mycobacterium leprae. The present study evaluated the association of single nucleotide polymorphisms (SNPs) on the FokI (rs2228570), TaqI (rs731236), ApaI (rs7975232) regions of the vitamin D receptor (VDR) gene with leprosy. A total of 405 individuals were evaluated, composed by groups of 100 multibacillary (MB) and 57 paucibacillary (PB) patients, and 248 healthy contacts. Blood samples were collected from patients and contacts. The genotyping was performed by sequencing of the interest regions. The alleles of the studied SNPs, and SNP FokI genotypes, were not associated with leprosy. For the SNP on TaqI region, the relationship between the tt genotype, and for the SNP ApaI, the AA genotype, revealed an association with susceptibility to MB form, while Aa genotype with protection. The extended genotypes AaTT and AaTt of ApaI and TaqI were associated with protection against MB form. Further studies analyzing the expression of the VDR gene and the correlation with its SNPs might help to clarify the role of polymorphisms on the immune response in leprosy.

Whole-Exome Sequencing for Identification of Genetic Variants Involved in Vitamin D Metabolic Pathways in Families With Vitamin D Deficiency in Saudi Arabia

Background

Numerous research studies have found an association between vitamin D (vitD) status and single-nucleotide polymorphisms (SNPs) in genes involved in vitD metabolism. It is notable that the influence of these SNPs on 25-hydroxyvitamin D [25(OH)D] levels might vary in different populations. In this study, we aimed to explore for genetic variants in genes related to vitD metabolism in families with vitD deficiency in Saudi Arabia using whole-exome sequencing (WES).

Methods

This family-based WES study was conducted for 21 families with vitD deficiency (n = 39) in Saudi Arabia. WES was performed for DNA samples, then resulting WES data was filtered and a number of variants were prioritized and validated by Sanger DNA sequencing.

Results

Several missense variants in vitD-related genes were detected in families. We determined two variants in low-density lipoprotein 2 gene (LRP2) with one variant (rs2075252) observed in six individuals, while the other LRP2 variant (rs4667591) was detected in 13 subjects. Single variants in 7-dehydrocholesterol reductase (DHCR7) (rs143587828) and melanocortin-1 receptor (MC1R) (rs1805005) genes were observed in two subjects from two different families. Other variants in group-specific component (GC), cubilin (CUBN), and calcium-sensing receptor (CASR) gene were found in index cases and controls. Polymorphisms in GC (rs9016) and CASR (rs1801726) were found in the majority of family cases (94 and 88%), respectively.

Conclusion

In vitD-deficient families in Saudi Arabia, we were able to detect a number of missense exonic variants including variants in GC (rs9016), CUBN (rs1801222), CASR (rs1801726), and LRP2 (rs4667591). However, the existence of these variants was not different between affected family members and non-affected controls. Additionally, we were able to find a mutation in DHCR7 (rs143587828) and a polymorphism in LRP2 (rs2075252), which may affect vitD levels and influence vitD status. Further studies are now required to confirm the association of these variants with vitD deficiency.

Vitamin D: Not Just Bone Metabolism but a Key Player in Cardiovascular Diseases

Vitamin D is the first item of drug expenditure for the treatment of osteoporosis. Its deficiency is a condition that affects not only older individuals but also young people. Recently, the scientific community has focused its attention on the possible role of vitamin D in the development of several chronic diseases such as cardiovascular and metabolic diseases. This review aims to highlight the possible role of vitamin D in cardiovascular and metabolic diseases. In particular, here we examine (1) the role of vitamin D in diabetes mellitus, metabolic syndrome, and obesity, and its influence on insulin secretion; (2) its role in atherosclerosis, in which chronic vitamin D deficiency, lower than 20 ng/mL (50 nmol/L), has emerged among the new risk factors; (3) the role of vitamin D in essential hypertension, in which low plasma levels of vitamin D have been associated with both an increase in the prevalence of hypertension and diastolic hypertension; (4) the role of vitamin D in peripheral arteriopathies and aneurysmal pathology, reporting that patients with peripheral artery diseases had lower vitamin D values than non-suffering PAD controls; (5) the genetic and epigenetic role of vitamin D, highlighting its transcriptional regulation capacity; and (6) the role of vitamin D in cardiac remodeling and disease. Despite the many observational studies and meta-analyses supporting the critical role of vitamin D in cardiovascular physiopathology, clinical trials designed to evaluate the specific role of vitamin D in cardiovascular disease are scarce. The characterization of the importance of vitamin D as a marker of pathology should represent a future research challenge.

Association of SNPs in GC and CYP2R1 with total and directly measured free 25-hydroxyvitamin D in multi-ethnic postmenopausal women in Saudi Arabia

Background

Group-specific component (GC) and cytochrome P450 Family 2 Subfamily R Member 1 (CYP2R1) genes are one of the vital genes involved in the vitamin D (vitD) metabolic pathway. Association of genetic polymorphisms in these two genes with 25-hyroxyvitamin D (25(OH)D) level has been reported in several studies. However, this association has been reported to be discrepant among populations from different ethnicities. Therefore, we aimed in this study to investigate association of the two major single nucleotide polymorphisms (SNP) in GC (rs4588 and rs7014) and a SNP (rs12794714) in CYP2R1 in postmenopausal women in Saudi Arabia.

Methods

This study randomly selected 459 postmenopausal women (aged ≥50 years) of multiple ethnicities in Jeddah, Saudi Arabia. Blood samples were collected from all participating women for DNA extraction and for assessment of serum levels of total 25(OH)D, directly measured free 25(OH)D and other biochemical parameters. SNPs in selected vitD related genes (rs4588 in GC, c.1364G > T with transcript ID: NM_001204307.1 and rs7041 in GC, c.1353A > C with transcript ID NM_001204307.1 and rs12794714 in CYP2R1, c.177G > A with transcript ID NM_024514.4) were determined in DNA samples using Sanger DNA sequencing.

Results

Minor allele frequency for rs4588, rs7041 and rs12794714 were 0.25, 0.44 and 0.42 respectively. Genotypes of rs7041 showed significant difference in total 25(OH)D level but not in free 25(O)D level (P = 0.023). In comparison, genotypes of rs4588 and rs12794714 did not show any significant difference neither in total nor in free 25(OH)D level. Post hoc test revealed that total 25(OH)D was lower in the rs7041 TT allele compared to the GG allele (P = 0.022). Chi-square test showed that vitD status was associated with rs7041 genotypes (P = 0.035). In addition, rs7041 minor alleles were found to have an association with vitD deficiency with a statistical significant odds ratio (>1) of 2.24 and 3.51 with P = 0.006 and P = 0.007 for TG and GG genotypes respectively.

Conclusion

The rs7041 SNP in GC was associated with total 25(OH)D level in postmenopausal women in Saudi Arabia, while rs4588 in GC and rs12794714 in CYP2R1 did not show association with total 25(OH)D. Further studies exploring additional variants in vitD related genes are needed to understand genetic factors underlying vitD deficiency in Saudi population.

Brief Report: CYP27B1 rs10877012 T Allele Was Linked to Non-AIDS Progression in ART-Naïve HIV-Infected Patients: A Retrospective Study

BACKGROUND

HIV/AIDS progression is linked to vitamin D, which is regulated by several key cytochromes P450 (CYP). Single nucleotide polymorphisms (SNPs) in CYP genes influence vitamin D metabolism and serum levels. The objective of this study was to evaluate the association between CYP SNPs and the clinical AIDS progression in antiretroviral treatment (ART)-naïve HIV-infected patients.

METHODS

We performed a retrospective study in 661 ART-naïve HIV-infected patients who were stratified by their AIDS progression pattern [181 long-term nonprogressors (LTNPs), 332 moderate progressors, and 148 rapid progressors (RPs)]. Four CYP SNPs (CYP2R1 rs10500804, CYP2R1 rs1993116, CYP27B1 rs10877012, and CYP24A1 rs6013897) were genotyped using Agena Bioscience's MassARRAY platform. Correction for multiple testing was performed using the false discovery rate (Benjamini-Hochberg procedure).

RESULTS

The adjusted regression showed a significant association only for CYP27B1 rs10877012 SNP. When analyzing all HIV patients, the rs10877012 T allele was protective against AIDS progression (ordinal outcome) under the dominant [adjusted odds ratio (aOR) = 0.69; P = 0.021) and additive (aOR) = 0.75; P = 0.025] inheritance models. When analyzing LTNPs versus RPs, the rs10877012 T allele also showed a significant protective association under the dominant (aOR = 0.45; P = 0.004) and additive (aOR = 0.54; P = 0.008) inheritance models. P values remained significant after correcting by multiple comparisons only for the comparison of LTNPs versus RPs (extreme phenotypes).

CONCLUSIONS

The CYP27B1 rs10877012 T allele was linked to non-AIDS progression in ART-naïve HIV-infected patients. The rs10877012 SNP seems to have an impact on the clinical AIDS progression, possibly modifying vitamin D levels, which could be relevant for the pathogenesis of HIV infection.

Rapid improvement in vitamin D status with dietary 25-hydroxycholecalciferol in vitamin D insufficient dogs

Vitamin D insufficiency is associated with various disease processes. We determined whether consumption of a diet supplemented with HyD^®, a 25-hydroxycholecalciferol (25(OH)D₃) source, would safely increase plasma 25(OH)D₃ concentrations in Golden Retrievers with low vitamin D status. We hypothesised that dietary supplementation with HyD^® would rapidly increase and sustain plasma 25(OH)D₃ levels in healthy Golden Retrievers with low vitamin D status compared with supplementation with vitamin D₃. Of fifty-seven privately owned dogs recruited with written owner consent, eighteen dogs with low vitamin D status were identified and sorted between two groups to have similar initial plasma 25(OH)D₃ concentrations, sex distributions, ages and body weights. Dogs of each group were fed a dry dog food supplemented with either 16 μg/kg of 25(OH)D₃ as HyD^® (n 10) or 81 μg/kg of cholecalciferol (D₃) (n 8) for 4 months. Plasma 25(OH)D₃ concentrations were determined monthly. A significant time effect (P < 0⋅001) and time by group interaction (P = 0⋅0045) were found for monthly determined plasma 25(OH)D₃ concentrations. Dogs fed the HyD^®-supplemented diet experienced a 40⋅5 % rise in plasma 25(OH)D₃ values after 1 month (P < 0⋅001) and no change thereafter. Plasma 25(OH)D₃ values of dogs supplemented with vitamin D₃ did not increase (P > 0⋅05) and were less than values of dogs supplemented with HyD^® (P = 0⋅044). With few exceptions, average haematologic, biochemical and urinalyses results remained within the reference range for both groups. Dietary supplementation with HyD^® is sufficient to safely increase and sustain plasma 25(OH)D₃ levels in healthy dogs.

Genotype-guided dietary supplementation in precision nutrition

Achieving adequate micronutrient status, while avoiding deficiencies, represents a challenge for people globally. Consequently, many individuals resort to oral nutrient supplementation (ONS) in order to correct suboptimal dietary intakes. Advances in the fields of nutrigenetics and nutritional genomics have identified differences in response to micronutrient supplementation according to genetic makeup, adding dietary supplement use to the clinician's toolkit in the precision nutrition era. This review focuses on published evidence linking genetic variants to the responses associated with some of the most popular dietary supplements. With an increasing number of health professionals becoming involved in the prescription of ONS, identifying and matching individuals to the appropriate dietary supplement according to their genotype is important for achieving optimal health benefits and micronutrient equilibrium, while reducing the adverse events and financial costs often associated with excessive ONS.

Genetic Variants Shaping Inter-individual Differences in Response to Dietary Intakes-A Narrative Review of the Case of Vitamins

Recent advances in the field of nutrigenetics have provided evidence on how genetic variations can impact the individuals' response to dietary intakes. An objective and reliable assessment of dietary exposures should rely on combinations of methodologies including frequency questionnaires, short-term recalls or records, together with biological samples to evaluate markers of intake or status and to identify genetic susceptibilities. In an attempt to present current knowledge on how genetic fingerprints contribute to an individual's nutritional status, we present a review of current literature describing associations between genetic variants and levels of well-established biomarkers of vitamin status in free-living and generally healthy individuals. Based on the outcomes of candidate gene, genome-wide-association studies and meta-analyses thereof, we have identified several single nucleotide polymorphisms (SNPs) involved in the vitamins' metabolic pathways. Polymorphisms in genes encoding proteins involved in vitamin metabolism and transport are reported to have an impact on vitamin D status; while genetic variants of vitamin D receptor were most frequently associated with health outcomes. Genetic variations that can influence vitamin E status include SNPs involved in its uptake and transport, such as in SCAR-B1 gene, and in lipoprotein metabolism. Variants of the genes encoding the sodium-dependent vitamin C transport proteins are greatly associated with the body's status on vitamin C. Regarding the vitamins of the B-complex, special reference is made to the widely studied variant in the MTHFR gene. Methodological attributes of genetic studies that may limit the comparability and interpretability of the findings are also discussed. Our understanding of how genes affect our responses to nutritional triggers will enhance our capacity to evaluate dietary exposure and design personalized nutrition programs to sustain health and prevent disease.

Tracking of serum 25-hydroxyvitamin D during 21 years

BACKGROUND/OBJECTIVES

Our objective was to evaluate the degree of tracking for serum levels of 25-hydroxyvitamin D [25(OH)D] over time, by using data from three previously conducted surveys of the Tromsø study collected in the years 1994/1995 (Tromsø 4), 2007/2008 (Tromsø 6), and 2015/2016 (Tromsø 7).

SUBJECTS/METHODS

Subjects with valid 25(OH)D measurements in all three surveys were included. 25(OH)D z-scores were used to adjust for seasonal variation. Z-scores and sextiles were used to illustrate tracking of 25(OH)D.

RESULTS

1702 subjects (572 males, 1130 females) fulfilled the inclusion criteria. Median (5th, 95th percentiles) age for these subjects was 55 (33, 65) years in Tromsø 4, and mean (SD) 25(OH)D levels were 57 (18) nmol/L, 59 (19) nmol/L, and 72 (21) nmol/L for Tromsø 4, Tromsø 6, and Tromsø 7, respectively. There was significant tracking of serum 25(OH)D over the 21 years period between the surveys of the Tromsø study. The correlation coefficient r between 25(OH)D z-scores from Tromsø 4 and Tromsø 6 was 0.40, and declined to 0.29 for the correlation between Tromsø 4 and Tromsø 7. Twenty-six percent of the subjects in the lowest 25(OH)D z-score sextile in Tromsø 4 were in the three highest sextiles of 25(OH)D in Tromsø 7. Similarly, 35% of those in the highest sextile in Tromsø 4 were in the lowest three sextiles in Tromsø 7.

CONCLUSIONS

The degree of tracking for serum 25(OH)D declines over time, and the use of a single serum 25(OH)D measurement as an indicator of the vitamin-D status is questionable if used in long-lasting observational studies.

Influence of vitamin D binding protein polymorphism, demographics and lifestyle factors on vitamin D status of healthy Malaysian pregnant women

BACKGROUND

Vitamin D deficiency (VDD) has been related to vitamin D binding protein (GC) gene polymorphism, demographics and lifestyle factors in different populations. However, previous studies only focused on demographic and lifestyle factors or genetic factors alone. Therefore, this cross-sectional study aimed to assess the association between GC gene polymorphism, demographics and lifestyle factors with VDD among Malaysian pregnant women.

METHOD

Information on demographic characteristics, dietary vitamin D intake from supplement and food, time spent outdoors, skin type and clothing were collected using a questionnaire. Plasma total 25-hydroxyvitamin D (25OHD) levels were measured using an Ultra-High-Performance Liquid Chromatography (UHPLC). Maternal GC single nucleotide polymorphisms (SNPs) (rs4588 and rs7041) were determined using restriction fragment length polymorphism (RFLP) technique.

RESULTS

Results showed that 50.2% of pregnant women were vitamin D deficient (25OHD < 30 nmol/L). VDD (25OHD < 30 nmol/L) was significantly associated with age, veiled clothing, maternal vitamin D intakes from both food and supplements, and GC rs7041(and GC diplotypes). In contrast to previous studies that reported for non-pregnant population, a significant positive association was found between CC genotype for SNP GC rs7041, GC 1s-1s and GC If-2 with risk of VDD (25OHD < 30 nmol/L).

CONCLUSIONS

The high prevalence of maternal VDD found in this study suggests the need for urgent development and implementation of vitamin D supplementation or fortification strategies to reduce VDD among pregnant women. The discrepancy in the association between GC rs7041 gene polymorphism and VDD reflects the variation in the factors associated with VDD in pregnancy compared to non-pregnant state.

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.

Placenta expression of vitamin D and related genes in pregnant women with gestational diabetes mellitus

OBJECTIVES AND METHODS

A total of 41 GDM and 40 normal glucose tolerance subjects were recruited. Through detecting the level of Serum vitamin D with electrochemical luminescence and vitamin D receptor (VDR) with Enzyme-linked immunosorbent assay (ELISA) in maternal and cord blood, the expression leves of CYP24A1, CYP27B1, VDR protein and mRNA in placenta and umbilical cord with western blotting and RT-PCR, and the DNA methylation levels of CYP24A1 and CYP27B1 gene in placenta with methylation-specific PCR (MSP) and direct bisulfite sequencing (BSP) analysis to explore the potential role of the vitamin D and its related genes in gestational diabetes mellitus (GDM).

RESULTS

Serum vitamin D concentrations were significantly higher in normal pregnant than women with GDM in maternal blood (P < 0.01) and cord blood (P = 0.014). Compared to the control group, the expression levels of CYP24A1 protein (P < 0.01) and mRNA (P = 0.021) and VDR protein (P = 0.026) and mRNA (P = 0.023) in the GDM group were significantly higher in placenta and umbilical cord tissues (P = 0.015, P < 0.01, P = 0.028, P < 0.01, respectively), while that of CYP27B1 protein (P < 0.01) and mRNA (P = 0.042) was significantly lower (P = 0.022, P = 0.032, respectively). Moreover, partial DNA methylation of CYP24A1 and CYP27B1 genes was observed in both GDM and control groups.

CONCLUSIONS

Vitamin D deficiency participates in the pathogenesis of GDM, and changes in the expression of genes related to the vitamin D metabolic pathway are closely related to vitamin D levels in the pregnancy and fetus. However, DNA methylation of CYP24A1 and CYP27B1 might not be involved in the pathogenesis of GDM.

Genomics in Personalized Nutrition: Can You "Eat for Your Genes"?

Genome-wide single nucleotide polymorphism (SNP) data are now quickly and inexpensively acquired, raising the prospect of creating personalized dietary recommendations based on an individual's genetic variability at multiple SNPs. However, relatively little is known about most specific gene-diet interactions, and many molecular and clinical phenotypes of interest (e.g., body mass index [BMI]) involve multiple genes. In this review, we discuss direct to consumer genetic testing (DTC-GT) and the current potential for precision nutrition based on an individual's genetic data. We review important issues such as dietary exposure and genetic architecture addressing the concepts of penetrance, pleiotropy, epistasis, polygenicity, and epigenetics. More specifically, we discuss how they complicate using genotypic data to predict phenotypes as well as response to dietary interventions. Then, several examples (including caffeine sensitivity, alcohol dependence, non-alcoholic fatty liver disease, obesity/appetite, cardiovascular, Alzheimer's disease, folate metabolism, long-chain fatty acid biosynthesis, and vitamin D metabolism) are provided illustrating how genotypic information could be used to inform nutritional recommendations. We conclude by examining ethical considerations and practical applications for using genetic information to inform dietary choices and the future role genetics may play in adopting changes beyond population-wide healthy eating guidelines.

The "Virtual Digital Twins" Concept in Precision Nutrition

Nutritional and lifestyle changes remain at the core of healthy aging and disease prevention. Accumulating evidence underscores the impact of genetic, metabolic, and host gut microbial factors on individual responses to nutrients, paving the way for the stratification of nutritional guidelines. However, technological advances that incorporate biological, nutritional, lifestyle, and health data at an unprecedented scale and depth conceptualize a future where preventative dietary interventions will exceed stratification and will be highly individualized. We herein discuss how genetic information combined with longitudinal metabolomic, immune, behavioral, and gut microbial parameters, and bioclinical variables could define a digital replica of oneself, a "virtual digital twin," which could serve to guide nutrition in a personalized manner. Such a model may revolutionize the management of obesity and its comorbidities, and provide a pillar for healthy aging.

Hypovitaminosis D and reduced cathelicidin are strongly correlated during the multidrug therapy against leprosy

Mycobacterium leprae infection depends on the competence of the host immune defense to induce effective protection against this intracellular pathogen. The present study investigated the serum levels of vitamin D and the antimicrobial peptide cathelicidin, to determine the statistical correlation between them in leprosy patients before and post-six months of multidrug therapy (MDT), household contacts, and healthy individuals. Previous studies associated these molecules with high risks to develop mycobacterial diseases, such as tuberculosis and leprosy. A total of 34 leprosy patients [paucibacillary (n = 14), multibacillary (n = 20)], and 25 household contacts were recruited. Eighteen healthy adults were selected as a control group. Serum concentrations of vitamin D (25(OH)VD₃) and cathelicidin were measured using high-performance liquid chromatography (HPLC), and an enzyme-linked immunosorbent assay (ELISA) kit, respectively. There were no significant differences in serum levels of 25(OH)VD₃ between all groups, and the overall prevalence rate of vitamin D deficiency was 67.1%. Cathelicidin levels were significantly lower in both untreated and treated patients when compared to controls and household contacts (p < 0.05). Strong correlations between hypovitaminosis D and reduced cathelicidin in untreated (r = 0.86) and post-six months of MDT (r = 0.79) leprosy patients were observed. These results suggest that vitamin D status and cathelicidin levels are strongly correlated during multidrug therapy for leprosy and nutritional supplementation from the beginning of treatment could strengthen the immune response against leprosy.

Effectiveness of vitamin D supplementation on the outcome of pulmonary tuberculosis treatment in adults: a meta-analysis of randomized controlled trials

Supplemental Digital Content is available in the text

Background:

Tuberculosis (TB) is one of the most debilitating diseases worldwide. Current studies have shown that vitamin D plays a significant role in host immune defense against Mycobacterium tuberculosis, but clinical trials reported inconsistent results. Therefore, we systematically reviewed the literature to investigate whether vitamin D supplementation could improve the effect of anti-TB therapy.

Methods:

We systematically searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials from their inception to February 8th, 2019 for randomized controlled trials on vitamin D supplementation in patients with pulmonary TB receiving anti-TB therapy. The primary outcomes were time to sputum culture and smear conversion and proportion of participants with negative sputum culture. The secondary outcomes were clinical response to treatment and adverse events. A random-effects model was used to pool studies. Data were analyzed using RevMan 5.3 software.

Results:

Five studies with a total of 1126 participants were included in our meta-analysis. Vitamin D supplementation did not shorten the time to sputum culture and smear conversion (hazard ratio [HR] 1.04, 95% confidence interval [CI] 0.89–1.23, P = 0.60; HR 1.15, 95% CI 0.93–1.41, P = 0.20, respectively) and did not lead to an increase in the proportion of participants with negative sputum culture (relative risk [RR] 1.04, 95% CI 0.97–1.11, P = 0.32). However, it reduced the time to sputum culture conversion in the sub-group of participants with TaqI tt genotype (HR 8.09, 95% CI 1.39–47.09, P = 0.02) and improved the multidrug-resistant (MDR) TB sputum culture conversion rate (RR 2.40, 95% CI 1.11–5.18, P = 0.03). There was no influence on secondary outcomes.

Conclusions:

Vitamin D supplementation had no beneficial effect on anti-TB treatment, but it reduced the time to sputum culture conversion in participants with tt genotype of the TaqI vitamin D receptor gene polymorphism and improved the MDR TB sputum culture conversion rate.

Vitamin D Deficiency and the Risk of Cerebrovascular Disease

Vitamin D deficiency has been clearly linked to major chronic diseases associated with oxidative stress, inflammation, and aging, including cardiovascular and neurodegenerative diseases, diabetes, and cancer. In particular, the cardiovascular system appears to be highly sensitive to vitamin D deficiency, as this may result in endothelial dysfunction and vascular defects via multiple mechanisms. Accordingly, recent research developments have led to the proposal that pharmacological interventions targeting either vitamin D deficiency or its key downstream effects, including defective autophagy and abnormal pro-oxidant and pro-inflammatory responses, may be able to limit the onset and severity of major cerebrovascular diseases, such as stroke and cerebrovascular malformations. Here we review the available evidence supporting the role of vitamin D in preventing or limiting the development of these cerebrovascular diseases, which are leading causes of disability and death all over the world.

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.

Single Nucleotide Polymorphisms in 25-Hydroxyvitamin D3 1-Alpha-Hydroxylase (CYP27B1) Gene: The Risk of Malignant Tumors and Other Chronic Diseases

: Vitamin D is widely known for its roles in the promotion of apoptosis and differentiation, with simultaneous inhibition of proliferation, inflammation, angiogenesis, invasion, and metastasis. Modern literature lacks complete information on polymorphisms in CYP27B1, the only enzyme capable of vitamin D activation. This review presents gathered data that relate to genetic variants in CYP27B1 gene in correlation to multiple diseases, mostly concerning colorectal, prostate, breast, lung, and pancreatic cancers, as well as on other pathologies, such as non-Hodgkin's lymphoma, oral lichen planus, or multiple sclerosis.

Variants rs1544410 and rs2228570 of the vitamin D receptor gene and glycemic levels in adolescents from Northeast Brazil

Introduction

Objective: to verify the association of serum concentrations of 25-hydroxyvitamin D and glycemic levels with the genetic variants rs1544410 and rs2228570 of the VDR gene in adolescents from the Northeast region of Brazil. Materials and methods: a cross-sectional epidemiological study with 208 adolescents from public schools in the city of João Pessoa (Paraíba, Brazil) between 15 and 19 years of age. Blood samples were collected for DNA extraction and analysis of polymorphisms rs1544410 and rs2228570, as well as biochemical analyses (25-hydroxyvitamin D, parathyroid hormone, calcium and glycemia). Results: the mean age was 17.7 (± 1.14) years. Half of adolescents had sufficient serum levels of 25-hydroxyvitamin D and the other half had insufficient/deficient vitamin. The most frequent genotypic distribution was bb and Ff and of lesser frequency BB and ff. There was a significant relationship between the genotypes of rs1544410 and glycemia values (p = 0.049) in the relationships between the genotypes BBxbb (p = 0.012) and Bbxbb (p = 0.037); (p = 0.036, OR = 2.15, 95% CI = 1.05-4.41), and in the BB+Bb group analysis when compared to the bb (p = 0.025, OR = 1.89, 95% CI = 1.08-3.29) presented higher risk of glycemia above the median. On the other hand, when Bb+bb was analyzed in relation to BB, adolescents had a greater chance of blood glucose below the median (p = 0.025, OR = 0.66, CI = 0.47-0.95). Conclusion: this study showed a significant relation of glycemia with the distribution of rs1544410 polymorphism genotypes.

Identification and analysis of 35 genes associated with vitamin D deficiency: A systematic review to identify genetic variants

Vitamin D deficiency is a public health concern associated with, but not limited to, skeletal anomalies, chronic diseases, immune conditions, and cancer, among others. Hypovitaminosis D is mainly associated with environmental and lifestyle factors that affect sunlight exposure. However, genetic factors also influence 25-hydroxyvitamin D (25[OH]D) serum concentration. Although there is available information of genes with clear biological relevance or markers identified by Genome-Wide Association Studies, an overall view and screening tool to identify known genetic causes of altered serum levels of 25(OH)D is lacking. Moreover, there are no studies including the total genetic evidence associated with abnormal serum concentration of 25(OH)D. Therefore, we conducted a de-novo systematic literature review to propose a set of genes comprehensive of all genetic variants reported to be associated with deficiency of vitamin D. Abstracts retrieved from PubMed search were organized by gene and curated one-by-one using the PubTerm web tool. The genes identified were classified according to the type of genetic evidence associated with serum 25(OH)D levels and were also compared with the few commonly screened genes related to vitamin D status. This strategy allowed the identification of 35 genes associated with serum 25(OH)D concentrations, 27 (75%) of which are not commercially available and are not, therefore, analyzed in clinical practice for genetic counseling, nor are they sufficiently studied for research purposes. Functional analysis of the genes identified confirmed their role in vitamin D pathways and diseases. Thus, the list of genes is an important source to understand the genetic determinants of 25(OH)D levels. To further support our findings, we provide a map of the reported functional variants and SNPs not included in ClinVar, minor allelic frequencies, SNP effect sizes, associated diseases, and an integrated overview of the biological role of the genes. In conclusion, we identified a comprehensive candidate list of genes associated with serum 25(OH)D concentrations, most of which are not commercially available, but would prove of importance in clinical practice in screening for patients that should respond to supplementation because of alterations in absorption, patients that would have little benefit because alterations in the downstream metabolism of vitamin D, and to study non-responsiveness to supplementation with vitamin D.

DKK1 Induced by 1,25D3 Is Required for the Mineralization of Osteoblasts

1α,25-dihydroxyvitamin D3 (1,25D3), the most popular drug for osteoporosis treatment, drives osteoblast differentiation and bone mineralization. Wnt/β-catenin signaling is involved in commitment and differentiation of osteoblasts, but the role of the Dickkopf-related protein 1 (DKK1), a Wnt antagonist, in osteoblasts remains unknown. Here, we demonstrate the molecular mechanism of DKK1 induction by 1,25D3 and its physiological role during osteoblast differentiation. 1,25D3 markedly promoted the expression of both CCAAT/enhancer binding protein beta (C/EBPβ) and DKK1 at day 7 during osteoblast differentiation. Interestingly, mRNA and protein levels of C/EBPβ and DKK1 in osteoblasts were elevated by 1,25D3. We also found that C/EBPβ, in response to 1,25D3, directly binds to the human DKK1 promoter. Knockdown of C/EBPβ downregulated the expression of DKK1 in osteoblasts, which was partially reversed by 1,25D3. In contrast, overexpression of C/EBPβ upregulated DKK1 expression in osteoblasts, which was enhanced by 1,25D3. Furthermore, 1,25D3 treatment in osteoblasts stimulated secretion of DKK1 protein within the endoplasmic reticulum to extracellular. Intriguingly, blocking DKK1 attenuated calcified nodule formation in mineralized osteoblasts, but not ALP activity or collagen synthesis. Taken together, these observations suggest that 1,25D3 promotes the mineralization of osteoblasts through activation of DKK1 followed by an increase of C/EBPβ.

The Eurasian lactase persistence variant LCT-13910 C/T is associated with vitamin D levels in individuals living at high latitude, more so than exposure to sunlight

Rapid selection of a genetic variant that confers continuous life-long lactase production in Europeans (LCT-13910 C/T) has been attributed to the advantages of acquiring nutrients from consuming milk without the disadvantages of lactose malabsorption. Individuals with this genetic lactase persistence (LP) variant generally consume more milk and have been shown to have higher levels of serum vitamin D. Vitamin D is the principal regulator of Ca absorption and its synthesis in skin is dependent on UVB exposure. The primary aim of the present study was to compare serum vitamin D concentrations with LP variant and to control for UVB exposure. Data from over 100 000 individuals living in Norway, a country with low UVB exposure, was retrospectively retrieved for comparison of genetic LP variant, serum 25-hydroxyvitamin D (25(OH)D) concentration and the time of year when serum samples were taken. For comparison, a similar analysis was performed with a natural dairy micronutrient, namely vitamin B₁₂. It was found that individuals with the genetic LP variant had considerably higher levels of serum 25(OH)D (P < 2 × 10^-16, Cohen's d = 0·73) but lower levels of vitamin B₁₂ (P < 2 × 10^-16, Cohen's d = 0·11), compared with genetic lactase non-persistent individuals, even when controlled for seasonality, age and sex. The difference in serum 25(OH)D levels did not diminish in summer months, showing the role of vitamin D in LP variant selection in areas of low UVB irradiation. LP variant selection advantage through acquiring another dairy micronutrient, vitamin B₁₂, was not observed.

Posttraumatic stress disorder is associated with reduced vitamin D levels and functional polymorphisms of the vitamin D binding-protein in a population-based sample

OBJECTIVE

Low levels of vitamin D were found to be associated with different mental disorders. However, the role of vitamin D in the pathogenesis of PTSD is unclear. In this study, we aimed at investigating whether PTSD is linked to reduced vitamin D levels and vitamin D deficiency. Moreover, we sought to investigate the role of the vitamin D-binding protein (also group-specific component or Gc) by testing if two functional polymorphisms (rs4588 and rs7041) were associated with vitamin D levels and PTSD.

METHODS

Serum levels of total 25(OH)D were measured in a general-population sample of the Study of Health in Pomerania (SHIP-1). The number of traumatic events and status of PTSD were assessed using the PTSD module of the Structured Clinical Interview for the DSM-IV. Study participants were genotyped for rs4588 and rs7041. Associations of 25(OH)D levels and the genotypes with PTSD were tested in subjects with at least one traumatic event (n = 1653).

RESULTS

25(OH)D levels were inversely (OR: 0.96; p = 0.044) and vitamin D deficiency was positively (OR = 2.02; p = 0.028) associated with PTSD. Both polymorphisms of the Gc were associated with 25(OH)D levels and PTSD: Carriers of the CC-genotype of rs4588 showed significantly higher 25(OH)D levels (ß = 0.179, p < 0.001) and lower odds for PTSD (OR = 0.35; p = 0.023) compared to the AA-genotype. Likewise, carriers of the TT-allele of rs7041 showed lower 25(OH)D levels (-0.122; p < 0.001) and increased odds for PTSD (OR = 2.80; p = 0.015) compared to the GG-genotype.

CONCLUSIONS

Our results suggest that an altered vitamin D metabolism may be involved in the pathophysiology of PTSD. Also, genotypes of the Gc and thus Gc serum levels may impact on PTSD development over and above the effects of 25(OH)D. Our findings contribute to explain the associations of PTSD with different mental and physical disorders.

Vitamin D Status in Russian Children and Adolescents: Contribution of Genetic and Exogenous Factors

Background: The problem of vitamin D deficiency is particularly relevant for the entire territory of Russia, since most parts of the country are located above the 42nd geographical latitude and the residents are therefore at risk of vitamin D deficiency. Despite the urgency of the problem, a comprehensive study of the molecular and genetic mechanisms and exogenous factors of vitamin D deficiency in children living in various geographical areas of the Russian Federation has not been conducted. Different variants in the loci of the genes responsible for the synthesis, hydroxylation, and transport of vitamin D (such as DHCR7, CYP2R1, CYP24A1, and GC), as well as VDR gene polymorphisms may also be associated with the risk of vitamin D deficiency. The aim of this study was to analyze the influence of exogenous factors on the blood levels of 25-hydroxyvitamin D (25(OH)D) in children of three regions of the Russian Federation, as well as the relationship of blood 25(OH)D levels with polymorphic variants of cytochrome P450 genes and VDR gene. Methods: We conducted blood 25(OH)D level analysis in 333 healthy children and adolescents in three regions located in different geographical zones of the Russian Federation. We studied the polymorphic variants c.1075A>C (I359L, rs1057910, CYP2C9 ^* 3) and c.430C>T (R144C, rs1799853, CYP2C9 ^* 2) in the CYP2C9 gene, c.1334T>C (M445T, rs4986910, CYP3A4 ^* 3), and CYP3A4 ^* 1B (c.-392C>T, rs2740574) in the CYP3A4 gene, 1846G>A, (rs3892097, CYP2D6 ^* 4) in the CYP2D6gene, TaqI (NM_000376.2: c.1056T>C; rs731236), FokI (NM_000376.2:c.2T>C; (rs2228570), and BsmI (NM_000376.2: c.1024+283G>A; rs1544410) in the VDR gene. We also analyzed the influence of exogenous factors on the level of 25(OH)D in children of the three study regions, as well as the relationship of the level of 25(OH)D with variants CYP2C9 ^* 2 (c.430C>T; R144C), CYP2C9 ^* 3 (c,1075A>C; I359L), CYP2D6 ^* 4 (1846G>A), CYP3A4 ^* 3 (c.1334T>C), and CYP3A4 ^* 1B (c.-392C>T) and rs731236, rs2228570 and rs1544410 in the VDR gene. Results: We found that the blood level of 25(OH)D depended on the geographical location and the number of sunny days per year. The average blood level of 25(OH)D in adolescent boys was statistically significantly lower than in girls of this age group. The level of 25(OH)D also significantly depended on the prophylactic dose of cholecalciferol administered to the subjects. In the study, it was shown that a dose of cholecalciferol ≥1,000 IU per day can achieve a normal level of 25(OH)D in healthy children. We found no statistically significant association between single-nucleotide polymorphic variants of cytochrome P450 genes (CYP2C9 ^* 3, CYP3A4 ^* 3, CYP2C9 ^* 2, CYP2D6 ^* 4, and CYP3A4 ^* 1B) and blood level of 25(OH)D in the subjects. We also did not find a relationship between the TaqI, FokI, and BsmI polymorphisms of the VDR gene and serum 25(OH)D concentration. Conclusion: Exogenous factors (time of year, place of residence, and prophylactic administration of cholecalciferol), as well as endogenous factors (age and sex), play a determining role in the development of vitamin D deficiency and insufficiency; in contrast to genetic factors-polymorphic variants of the genes of xenobiotic phase 1 enzymes (CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and the VDR gene-which do not play such role. This study shows the need to create a diagnostic algorithm for Vitamin D deficiency based on the age, season of the year, and prophylactic dose of cholecalciferol.

Association of circulating 25-hydroxyvitamin D levels with hypertension and blood pressure values in Korean adults: A Mendelian randomization study on a subset of the Korea National Health and Nutrition Survey 2011-2012 population

BACKGROUND/OBJECTIVES

Lower circulating 25-hydroxyvitamin D [25(OH)D] levels are associated with a higher risk of hypertension (HTN); however, it remains unclear whether the relationship is causal. We aimed to evaluate the causal effects of circulating 25(OH)D levels on the prevalence of HTN in the Korean population using the Mendelian randomization (MR) approach.

SUBJECTS/METHODS

Epidemiological data, serum 25(OH)D data, and genomic DNA biospecimens were obtained from 2,591 participants, a subset of the study population in the Korea National Health and Nutrition Survey 2011-2012. Five 25(OH)D-related single nucleotide polymorphisms (SNPs; DHCR7 rs12785878, CYP2R1 rs10741657, CYP2R1 rs12794714, CYP24A1 rs6013897, and GC rs2282679), identified a priori from genome-wide association studies, were used as instrument variables (IVs) for serum 25(OH)D levels. In the MR analysis, we performed IV analyses using the two-stage least squares method.

RESULTS

In the observational analysis, circulating 25(OH)D levels were found to be inversely associated with the HTN prevalence in ordinary least squares models (odds ratio: 0.97, 95% confidence interval: 0.96, 0.99) after adjusting for the potential confounders. There were differences in the circulating 25(OH)D levels across genotypes of individual SNPs. In the MR analysis, using individual SNPs as IVs, 25(OH)D levels were not associated with the HTN prevalence.

CONCLUSIONS

We found no association between genetically determined circulating 25(OH)D levels and HTN in Korean adults. Our results are listed owing to the relatively small sample size and possible weak instrument bias; therefore, further studies are needed to confirm these results.

DBP rs16846876 and rs12512631 polymorphisms are associated with progression to AIDS naïve HIV-infected patients: a retrospective study

Background

Most of the circulating Vitamin D (VitD) is transported bound to vitamin D-binding protein (DBP), and several DBP single nucleotide polymorphisms (SNPs) have been related to circulating VitD concentration and disease. In this study, we evaluated the association among DBP SNPs and AIDS progression in antiretroviral treatment (ART)-naïve-HIV-infected patients.

Methods

We performed a retrospective study in 667 patients who were classified according to their pattern of AIDS progression (183 long-term non-progressors (LTNPs), 334 moderate progressors (MPs), and 150 rapid progressors (RPs)) and 113 healthy blood donors (HIV, HCV, and HBV negative subjects). We genotyped seven DBP SNPs (rs16846876, rs12512631, rs2070741, rs2282679, rs7041, rs1155563, rs2298849) using Agena Bioscience’s MassARRAY platform. The genetic association was evaluated by Generalized Linear Models adjusted by age at the moment of HIV diagnosis, gender, risk group, and VDR rs2228570 SNP. Multiple testing correction was performed by the false discovery rate (Benjamini and Hochberg procedure; q-value).

Results

All SNPs were in HWE (p > 0.05) and had similar genotypic frequencies for DBP SNPs in healthy-controls and HIV-infected patients. In unadjusted GLMs, we only found significant association with AIDS progression in rs16846876 and rs12512631 SNPs. In adjusted GLMs, DBP rs16846876 SNP showed significant association under the recessive inheritance model [LTNPs vs. RPs (adjusted odds ratio (aOR) = 3.53; q-value = 0.044) and LTNPs vs. MPs (aOR = 3.28; q-value = 0.030)] and codominant [LTNPs vs. RPs (aOR = 4.92; q-value = 0.030) and LTNPs vs. MPs (aOR = 3.15; q-value = 0.030)]. Also, we found DBP rs12512631 SNP showed significant association in the inheritance model dominant [LTNPs vs. RPs (aOR = 0.49; q-value = 0.031) and LTNPs vs. MPs (aOR = 0.6; q-value = 0.047)], additive [LTNPs vs. RPs (aOR = 0.61; q-value = 0.031)], overdominant [LTNPs vs. MPs (aOR = 0.55; q-value = 0.032)], and codominant [LTNPs vs. RPs (aOR = 0.52; q-value = 0.036) and LTNPs vs. MPs (aOR = 0.55; q-value = 0.032)]. Additionally, we found a significant association between DBP haplotypes (composed by rs16846876 and rs12512631) and AIDS progression (LTNPs vs RPs): DBP haplotype AC (aOR = 0.63; q-value = 0.028) and the DBP haplotype TT (aOR = 1.64; q-value = 0.028).

Conclusions

DBP rs16846876 and rs12512631 SNPs are related to the patterns of clinical AIDS progression (LTNP, MP, and RP) in ART-naïve HIV-infected patients. Our findings provide new knowledge about AIDS progression that may be relevant to understanding the pathogenesis of HIV infection.

Vitamin D pathway related polymorphisms and vitamin D receptor expression in breast cancer

Vitamin D deficiency is an emerging risk factor for breast cancer suggesting its role in breast cancer pathogenesis. Recent evidence suggests vitamin D receptor (VDR) expression is a prognosis predictor in breast cancer. We set out to determine the status of VDR expression in histologically characterized breast cancers, and whether common genetic variants modify VDR expression in breast cancer. One-hundred and twenty Kuwaiti female breast cancer fixed tissues were assessed for VDR expression to identify the level and location of its expression by immunohistochemistry. VDR variants (rs731236, rs2228570), and vitamin D binding protein (VDBP) variants (rs4588, rs7041) genotypes were ascertained in breast cancer specimens using Taqman genotyping assays. VDR nuclear expression correlated with low grade tumors (p = 0.01), whereas cytoplasmic expression correlated with lymph node positive tumors (p = 0.03). Absence of VDR expression was a marker for high-grade dedifferentiated tumors (p = 0.01). VDBP rs7041 associated with breast cancer risk (OR 1.92, 95% CI: 1.34 - 2.73; p = 0.0004), and VDR rs2228570 correlated with increased VDR cytoplasmic expression (p < 0.0001). In conclusion, VDR expression is altered in breast cancer confirming its involvement in breast cancer progression. Genetic factors appear to play a role in breast cancer risk, and may modify tumor sensitization to vitamin D.