Association between vitamin D receptor gene FokI polymorphism and atopic childhood bronchial asthma

The serum level of vitamin D and prevalence of vitamin D deficiency among children with asthma in Asia and Africa: a systematic review and meta-analysis

BACKGROUND

Several studies on the serum level of vitamin D and the percentage of vitamin D deficiency in children with asthma have been conducted in Asia and Africa, but the results have been inconsistent and inconclusive, requiring a systematic review and meta-analysis to assess the strength of the evidence.

OBJECTIVE

The objective of this review is to synthesize evidence on serum levels of vitamin D and the percentage of vitamin D deficiency among children with asthma in Asia and Africa.

METHODS

To identify relevant articles, a comprehensive search was conducted across various databases and repositories such as PubMed, Google Scholar, Hinary, Web of Science, ResearchGate, as well as gray literature sources. The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were followed during the retrieval process. Data extraction was performed following a standardized format based on the JBI (Joanna Briggs Institute) data extraction guidelines. Microsoft Excel was utilized for data extraction, and subsequently, the data was exported to STATA 17 for further analysis. To assess the heterogeneity among the included studies, Cochrane Q-statistics and the I2 tests were employed. Publication bias was assessed using the Egger test and funnel plot.

RESULT

This meta-analysis investigated 33 articles encompassing a total of 3432 children diagnosed with asthma. The findings demonstrated that in low- or middle-income countries across Africa and Asia, children with asthma had an average serum vitamin D level of 21.9 ng/ml (95% confidence interval [CI]: 18.0-25.9 ng/ml), with 53.7% (95% CI: 40.5-66.9) experiencing vitamin D deficiency. Additionally, when considering the continent, children with asthma in Asia had an average serum vitamin D level of 18.5 ng/ml (95% CI: 13.8-23.3), while those in Africa had a level of 28.7 ng/ml (95% CI: 22.7-34.8). The analysis further explored different sub-group analyses. Depending on the study design, case-control studies yielded an average serum vitamin D level of 20.3 ng/ml (95% CI: 18.2-22.4), whereas cross-sectional studies resulted in 23.8 ng/ml (95% CI: 17.5-30.1). Based on publication year, studies published on or before 2015 had an average serum level of 21.0 ng/ml (95% CI: 18.0-24.0), while those published after 2015 had a level of 22.4 ng/ml (95% CI: 17.2-27.7). Moreover, when considering sample size, studies with 100 participants or less had an average serum level of 21.7 ng/ml (95% CI: 17.3-26.1), while studies with more than 100 participants had a level of 22.1 ng/ml (95% CI: 18.6-25.6).

CONCLUSION

Children with asthma in Asia and Africa were found to have low serum levels of vitamin D and a high percentage of vitamin D deficiency. This highlights the importance of early detection and monitoring of vitamin D levels in these children to prevent potential complications associated with vitamin D deficiency. Taking proactive measures to address and manage vitamin D deficiency is crucial for the well-being of children with asthma in these regions.

Genetic Diversity in Bronchial Asthma Susceptibility: Exploring the Role of Vitamin D Receptor Gene Polymorphisms in Varied Geographic Contexts

Bronchial asthma (BA) exhibits varying prevalence across global populations, prompting a comprehensive investigation into genetic and environmental determinants. Vitamin D is a potent immunomodulator capable of suppressing inflammatory signals in several cell types involved in the asthmatic response; it exerts effects on the immune system by binding to the nuclear vitamin D receptor (VDR). VDR gene genetic variations are affecting serum vitamin D levels with a possible role in the BA risk. The current study aimed to examine the complex interaction of various factors (genetic background, serum vitamin D levels, and geographic location) to identify differences in the influence of these factors on the susceptibility to asthma between populations at different latitudes. Focusing on Eastern European cohorts from Latvia and Lithuania and comparing them with published data on East Asian populations, we explore the impact of VDR gene polymorphisms on BA susceptibility. Genotyping four key VDR SNPs and assessing their association with 25-hydroxyvitamin D levels, our study unveils significant associations of the studied loci with the risk of asthma-both risk-reducing and increasing effects, differently distributed between Baltic and East Asian populations. The functional effects of in silico VDR gene genetic variations are also identified and discussed.

Plasma 25-Hydroxyvitamin D Level and VDR Gene Single Nucleotide Polymorphism rs2228570 Influence on COVID-19 Susceptibility among the Kazakh Ethnic Group-A Pilot Study

Low plasma levels of the vitamin D metabolite 25-hydroxyvitamin D [25(OH)D] and the vitamin D receptor (VDR) gene single nucleotide polymorphisms (SNPs) have been associated with the body's susceptibility to infectious diseases, including COVID-19. In this pilot retrospective study, representatives of the Kazakh population (central Kazakhstan) were divided into groups based on the test for IgM and IgG for coronavirus infection. We compared the 25(OH)D plasma levels and concluded that the COVID-19-positive group values (25.17 ng/mL ± 16.65) were statistically lower (p = 0.0114) compared to the COVID-19-negative ones (35.58 ng/mL ± 20.67). There was no association between age, gender and 25(OH)D concentration within the groups (p > 0.05). The genotyping of rs2228570 was performed using a TaqMan Real-Time PCR assay. Allele C predominated among the COVID-19-negative participants and significantly reduced the likelihood of coronavirus infection (p < 0.0001; OR = 0.0804; 95% CI 0.02357-0.2798). There were no statistically significant differences in the frequencies of the A, G and T alleles in the studied groups (p > 0.05). The GG genotype of rs2228570 was associated with a 4.131-fold increased likelihood of COVID-19 infection (p = 0.0288; χ2 = 5.364; OR = 4.131; 95% CI 1.223-13.71). Comprehensive studies are required to determine whether low 25(OH)D plasma concentrations and genetic background represent a risk factor for COVID-19 infection.

Association of vitamin D gene polymorphisms in children with asthma - A systematic review

INTRODUCTION

The association of Vitamin D and children with asthma is known and there are several individual studies on Vitamin D polymorphisms. However, systematic reviews on all vitamin D associated gene polymorphisms have not been done in children with asthma.

OBJECTIVE

To investigate the association of Vitamin D associated gene polymorphisms and asthma in children (0-18 years) by systematic review and meta-analytic approach.

METHODS

Our search included 20 full text articles of which 15 were case control studies and 5 used family based linkage disequilibrium method. Total of 2491cases and 3682 controls were included in case control studies, with mean age of 9.58 years and 10.16 years respectively. Quantitative and qualitative analysis were done.

RESULTS

Quantitative analysis revealed significant association with protective effect of Apa1 polymorphism in allele (OR 0.81 (0.71,0.91) and homozygous major form (OR 0.83 (0.70,0.98) and Taq 1 minor allele in homozygous form (OR 0.73 (0.58,0.92) in children with asthma. However, the minor allele of Apa1(OR 1.21 (1.07,1.37), Bsm 1 in heterozygous (OR 1.35 (1.07,1.71) and homozygous minor form (OR 1.95 (1.59,2.39), major allele of Fok1(OR1.34 (1.17,1.52) and Taq1 (OR 1.22 (1.08,1.38) were found to be increasing the odds of asthma. Ethnic variations were noted in subgroup analysis. Qualitative analysis of the polymorphisms of the Vitamin D associated metabolic genes also showed significant associations.

CONCLUSION

Our review shows significant associations with VDR polymorphisms - Apa1, Bsm1, Fok 1, Taq 1, polymorphisms of Vitamin D metabolic genes - CYP27A1, CYP 2R1, CYP 24A1, GC and genes related to Vitamin D response element (VDRE) in children with asthma. Conducting large studies involving various ethnic regions will strengthen our knowledge on the association and aid in targeted interventions for control of asthma in children.

Effects of genetic polymorphisms in Vitamin D metabolic pathway on Vitamin D level and asthma control in South Indian patients with bronchial asthma

Objectives:

The study was designed to evaluate the single-nucleotide polymorphisms (SNPs) of genes involved in Vitamin D actions (rs2228570) and metabolic pathways (rs2248137 and rs10766197) and their associations with serum 25-hydroxy Vitamin D (25(OH)D) level and asthma control in South Indian patients with bronchial asthma.

Materials and Methods:

One hundred and two patients of South Indian origin with bronchial asthma either naive to inhaled corticosteroids (ICSs) or not receiving ICS for ≥1 month were included and were treated with ICS (beclomethasone 200 μg twice daily) for 8 weeks. One hundred and one unrelated healthy South Indians were used as controls. Pulmonary function test and fractional exhaled nitric oxide were used to assess asthma control. Serum 25(OH)D levels (chemiluminescence immunoassay) and SNPs in Vitamin D pathway (real-time polymerase chain reaction) were assessed. The associations of SNPs and serum 25(OH)D with asthma control was determined using linear regression. All analyses were performed using SPSS (version 19) and “SNPStats.” P < 0.05 was considered as statistically significant.

Results:

Vitamin D receptor (VDR) polymorphism (rs2228570) was found to be protective against asthma (P = 0.022), while there were no significant associations between the other two SNPs and asthma. Similarly, poor correlation and insignificant associations between the SNPs and serum 25(OH)D levels were observed in both cases and controls. There were also insignificant associations between the SNPs and asthma control.

Conclusion:

VDR polymorphism (rs2228570) was found to be protective against asthma in South Indians, while other genes involved in the metabolic pathway of Vitamin D did not show associations with asthma.

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

Polymorphisms in genes encoding proteins involved in vitamin D metabolism and transport are recognised to influence vitamin D status. Syntheses of genetic association studies linking these variants to non-skeletal health outcomes are lacking. We therefore conducted a literature review to identify reports of statistically significant associations between single nucleotide polymorphisms (SNP) in 11 vitamin D pathway genes (DHCR7, CYP2R1, CYP3A4, CYP27A1, DBP, LRP2, CUB, CYP27B1, CYP24A1, VDR and RXRA) and non-bone health outcomes and circulating levels of 25-hydroxyvitamin D (25[OH]D and 1,25-dihydroxyvitamin D (1,25[OH]₂D). A total of 120 genetic association studies reported positive associations, of which 44 investigated determinants of circulating 25(OH)D and/or 1,25(OH)₂D concentrations, and 76 investigated determinants of non-skeletal health outcomes. Statistically significant associations were reported for a total of 55 SNP in the 11 genes investigated. There was limited overlap between genetic determinants of vitamin D status and those associated with non-skeletal health outcomes: polymorphisms in DBP, CYP2R1 and DHCR7 were the most frequent to be reported to associate with circulating concentrations of 25(OH)D, while polymorphisms in VDR were most commonly reported to associate with non-skeletal health outcomes, among which infectious and autoimmune diseases were the most represented.

Vitamin D levels and vitamin D receptor gene polymorphisms in asthmatic children: a case-control study

BACKGROUND

Vitamin D deficiency and single nucleotide polymorphisms (SNP) in the gene encoding vitamin D receptor (VDR) have been associated with asthma.

OBJECTIVE

To compare 25-hydroxyvitamin D (25OHD) levels and the frequency of 3 SNPs in the VDR gene between asthmatic and healthy children.

METHODS

In persistent asthmatic and healthy control children, the 25OHD levels were measured using radioimmunoassay and SNPs (FokI, ApaI, and TaqI) were analyzed by a PCR-RFLP assay. Relevant medical history was collected.

RESULTS

About 75 asthmatic (median age: 9.1 years) and 227 healthy children (10.3 years) were studied. In the whole population, the proportion of sufficient, insufficient, and deficient levels of 25OHD were 14.9%, 44%, and 41.1%, respectively. 25OHD sufficiency status was similar in asthmatic and healthy children (p = 0.57). However, the proportion of 25OHD sufficient levels among asthmatics according to the Global Initiative for Asthma treatment steps 2, 3, and 4 was significantly different (8.6%, 16.6%, and 43.7%, respectively, p = 0.046). All patients on step 4 of the treatment (16/16) were heterozygous for the C allele (FokI VDR SNP). There was a lower presence of the C allele among asthmatics in step 2 (30/33), step 3 (16/24), and controls (45/50), p = 0.007, but this significance did not persist after logistic regression. No significant differences in ApaI and TaqI were found.

CONCLUSIONS

We found a possible association of vitamin D sufficiency status and FokI C allele with higher requirement of therapy to reach asthma control, suggesting that it may be involved in treatment response. Variations in VDR might also play a role in the 25OHD levels.