Association of ApaI and BsmI polymorphisms with vitiligo risk: a meta-analysis

Vitamin D Receptor Gene Polymorphisms and Association with Vitiligo in Indonesian Population

Introduction

Vitiligo is an acquired depigmenting skin disorder due to the loss of melanocyte function in the epidermis and hair follicles. The pathogenesis of vitiligo is multifactorial, with genetics being a predisposing factor. Previous studies had varying results regarding whether or not polymorphisms of vitamin D receptor (VDR) gene are associated with the risk of vitiligo in specific populations. This study investigated the association between three frequently analyzed VDR gene polymorphisms (ApaI, BsmI, TaqI) and susceptibility to vitiligo in Indonesian population.

Methods

Thirty-four vitiligo patients and 34 age- and sex-matched healthy subjects aged ≥18 years old were recruited in the Dermatology and Venereology Outpatient Clinic of Dr. Hasan Sadikin General Hospital, Bandung, Indonesia. Genomic deoxyribonucleic acid (DNA) was extracted from the peripheral blood using a DNA isolation kit. VDR gene polymorphisms (ApaI, BsmI, and TaqI) were investigated using the polymerase chain reaction-restriction-fragment length polymorphism method. The differences of genotype distributions and allele frequencies were statistically compared between case and control groups using Chi-square test.

Results

VDR gene polymorphisms were identified in 68 participants, consisting of Aa (n = 14), aa (n = 20), Bb (n = 15), bb (n = 19), and TT (n = 34) genotypes in the case group. In the control group, Aa (n = 6), aa (n = 28), Bb (n = 17), bb (n = 17), and TT (n = 34) genotypes were identified. However, only subjects with ApaI Aa genotype polymorphism had a 3.267-fold increased risk of developing vitiligo.

Conclusion

This study showed that ApaI Aa genotype polymorphism of the VDR gene increases the risk of vitiligo in Indonesian population.

Evaluation of vitamin D receptor gene polymorphisms (ApaI and TaqI) as risk factors of vitiligo and predictors of response to narrowband UVB phototherapy

Vitiligo is acquired depigmentation due to multiple factors. Vitamin D in skin, through its receptors (VDR), regulates cell growth, differentiation, immune response and exerts both stimulatory and protective effects on melanocytes. The gene sequence encoding VDR has polymorphic forms such as ApaI and TaqI that may affect vitamin D actions. Narrowband ultraviolet B (NB-UVB) phototherapy became the mainstay of vitiligo treatment because of its efficacy and little side effects. The current work aimed at evaluating the possible association between VDR gene polymorphisms (TaqI and ApaI) and susceptibility of vitiligo and if they could be predictors of response to NB-UVB phototherapy in Egyptian vitiligo patients. 100 vitiligo patients indicated for NB-UVB phototherapy and 100 healthy age and sex matched controls were included. All participants were subjected to history taking, general and dermatological examinations, and VDR ApaI and TaqI gene polymorphisms analysis by PCR-RFLP. The patients received NB-UVB 3times per week for 6 months then revaluated. There was significant increase in Aa genotype of ApaI polymorphism in patients associated with significant increase in vitiligo activity. 66% of patient showed variable degrees of response to NB-UVB. The responders significantly had AA genotype of ApaI polymorphism. TaqI polymorphism showed nonsignificant effects on vitiligo susceptibility and response to NB-UVB. A allele of ApaI was significant independent predictor of NB-UVB phototherapy responders. VDR gene polymorphism (ApaI) may share in vitiligo pathogenesis and response to NB-UVB. Knowing the genetic background of the patient helps individualization of treatment to get better results.

Association between vitamin D receptor polymorphisms and vitiligo susceptibility: An updated meta-analysis

BACKGROUND

Vitamin D receptor (VDR) polymorphisms may play an important role in the vitiligo susceptibility. There have been many studies looking at the associations between VDR polymorphisms and vitiligo risk, but the conclusions are still up for debate.

AIM

This study aimed to determine whether polymorphisms in the VDR are associated to the susceptibility to vitiligo.

METHODS

Vitamin D receptor polymorphisms in vitiligo patients and controls were identified using PubMed/Medline and Embase databases. The relationships between the VDR ApaI, TaqI, BsmI, and TaqI polymorphisms and vitiligo were investigated using meta-analyses of all participants and Asian, Arab, European, and Latin American groups.

RESULTS

This meta-analysis included 13 papers with 2034 patients and 2771 controls. In all individuals, there was no link between vitiligo and the VDR ApaI A allele (OR = 0.889, 95% CI = 0.713-1.109, p = 0.298). However, in Asians (OR = 0.721, 95% CI = 0.553-0.940, p = 0.016) but not in Europeans or Arabs, there was a link between the VDR ApaI A allele and vitiligo. Utilizing recessive, dominant, and homozygote contrast models, a link between vitiligo and the VDR ApaI polymorphism was discovered in Asians. Meta-analysis of the VDR BsmI polymorphism showed a significant association between vitiligo and the B allele (OR = 0.812, 95% CI = 0.686-0.961, p = 0.015). In contrast, no connection between vitiligo and VDR polymorphisms was identified for TaqI and FokI polymorphisms.

CONCLUSION

In the Asian population, ApaI and BsmI polymorphisms in VDR have been correlated to vitiligo susceptibility. However, TaqI and FokI polymorphisms in VDR are not associated with vitiligo susceptibility in European, Asian, Arab, and Latin American populations.

How Does Vitamin D Affect Immune Cells Crosstalk in Autoimmune Diseases?

Vitamin D is a secosteroid hormone that is highly involved in bone health. Mounting evidence revealed that, in addition to the regulation of mineral metabolism, vitamin D is implicated in cell proliferation and differentiation, vascular and muscular functions, and metabolic health. Since the discovery of vitamin D receptors in T cells, local production of active vitamin D was demonstrated in most immune cells, addressing the interest in the clinical implications of vitamin D status in immune surveillance against infections and autoimmune/inflammatory diseases. T cells, together with B cells, are seen as the main immune cells involved in autoimmune diseases; however, growing interest is currently focused on immune cells of the innate compartment, such as monocytes, macrophages, dendritic cells, and natural killer cells in the initiation phases of autoimmunity. Here we reviewed recent advances in the onset and regulation of Graves' and Hashimoto's thyroiditis, vitiligo, and multiple sclerosis in relation to the role of innate immune cells and their crosstalk with vitamin D and acquired immune cells.

Association of genetic variants of the vitamin D receptor gene with vitiligo in a tertiary care center in a Saudi population: a case-control study

BACKGROUND

Vitiligo is a common cutaneous disorder of the skin and hair caused by a systemic depigmentation disorder that affects 1% of the population or less due to its onset in early adulthood. Meta-analyses have documented a linkage between vitiligo and the vitamin D receptor (VDR) gene.

OBJECTIVE

Investigate the relationship between the ApaI, BsmI, FokI and TaqI genetic variants in the VDR gene with vitiligo in a Saudi population.

DESIGN

Case-control.

SETTING

Single tertiary care center.

PATIENT AND METHODS

The case-control study was carried out between January 2015-December 2015 in Saudi vitiligo patients and healthy controls. VDR genetic variants or polymorphisms (ApaI, BsmI, FokI and TaqI) were genotyped by polymerase chain reaction-restriction fragment length analysis followed by 3% agarose gel electrophoresis. Applicable statistical methods were used to assess relationships between vitiligo cases and controls.

MAIN OUTCOM MEASURE

Effect of genotype distribution among four single nucleotide polymorphisms.

SAMPLE SIZE

152 vitiligo (median [IQR] 23 [19] years) patients and 159 healthy controls (45 [28.5] years).

RESULTS

We found an association of vitiligo with ApaI and BsmI polymorphisms (P<.05). However, a decreased risk was noted in vitiligo patients with FokI and TaqI polymorphisms and in the diplotype and haplotype analysis within males and females. A positive association with vitiligo was observed in ACAC and AC (adjusted by gender) haplotypes (P<.05). The strongest linkage disequilibrium was observed between rs79785232 (ApaI) and rs731236 (TaqI) polymorphisms (r²=.83), followed by rs2228570 (FokI) and rs1544410 (BsmI) polymorphisms (r²=.53).

CONCLUSIONS

Our results confirm an association of vitiligo with ApaI and BsmI polymorphisms and fail to show an association in TaqI and FokI polymorphism with vitiligo. Additional studies need to be carried out in different Arab populations to determine whether the polymorphisms are present.

LIMITATIONS

Controls not age matched, small sample size, lack of biochemical parameters.

CONFLICT OF INTEREST

None.

Impact of vitamin D receptor gene polymorphisms on vitiligo susceptibility and clinical features in a Southeastern European Caucasian population

An association of vitamin D receptor (VDR) polymorphisms and vitiligo has been suggested. However, previous studies have reported contradictory results while including limited data among Caucasians. The aim of this single-center study was to evaluate the effect of three common VDR gene polymorphisms (FokI, TaqI and BsmI) on suscep-tibility and clinical aspects of vitiligo in a Southeastern European Caucasian population. A total of 110 unrelated vitiligo cases and 509 general population controls were enrolled from October 2018 to November 2019. Genomic DNA was extracted from whole blood after de-identification and anonymization of the samples and genotyped for the selected VDR polymorphisms by the qPCR (melting curve analysis). Subgroup analysis by clinical features among subsets of patients indicated that, compared to subjects with the FokI TT genotype or T allele, carriers of the FokI CC genotype or C allele exhibited significantly decreased risk of developing vitiligo before the age of 30 [TT vs. CC: odds ratio (OR)=0.286, 95% confidence interval (CI): 0.083-0.984, P=0.041; T vs. C: OR=0.545, 95% CI: 0.313-0.948, P=0.031]. Intra-patient analysis also revealed that, compared to T allele, the presence of TaqI C allele was adversely associated with the incidence of concurrent leukotrichia (T vs. C: OR=1.874, 95% CI: 1.018-3.451, P=0.042). Comparisons between the case and control groups showed no evidence to support an association between susceptibility to vitiligo and the VDR BsmI, TaqI, and FokI polymorphisms in this cohort. Thus, the studied VDR polymorphisms might indirectly impact the clinical course and treatment decision-making despite their lack of association with vitiligo per se. Further research with larger sample sizes, especially across Caucasian individuals, should be performed to confirm these findings.

Vitamin D and the skin: what should a dermatologist know?

Although first discovered in 1931, vitamin D has seen an increased interest in the scientific community over the past decades, including the dermatology field. Vitamin D promotes calcium and phosphorus absorption; however, the actions of vitamin D are not confined to bone. Indeed, there is now overwhelming and compelling scientific data that vitamin D plays a crucial role in a plethora of cellular function and in extra-skeletal health. Except for fatty fish livers, very few foods naturally contain vitamin D; and the major source of vitamin D comes from skin exposure to sunlight via ultraviolet B. Keratinocytes are unique in the body as not only do they provide the primary source of vitamin D for the body, but they also possess both the enzymatic machinery to metabolize the vitamin D produced to active metabolites. This has been referred to as the photoendocrine vitamin D system. Vitamin D regulates keratinocytes proliferation and differentiation; and plays a role in the defense against opportunistic infections. Multiple factors are linked to vitamin D status; and a growing number of dermatologic diseases has been linked to vitamin D status such as atopic dermatitis, psoriasis, vitiligo, and cutaneous cancers. In this article, we reviewed the potential determinants of vitamin D status, as its implications in dermatologic diseases.

Association between parental autoimmune disease and atopic dermatitis in their offspring: a matched case-control study

BACKGROUND

Atopic dermatitis (AD) is associated with many autoimmune diseases, in part due to overlapping genetic risk loci. While parental atopic disease is an important risk for AD in the offspring, little is known on the putative associations between parental autoimmune disease and AD in their children.

MATERIALS AND METHODS

All children born between 1996 and 2011 who received a diagnosis of AD in the hospital system before their fifth birthday were matched 1 : 10 with children from the general population. Maternal and paternal autoimmune diseases were assessed using registry-based data. Conditional logistic regression was performed on the relationships between parental autoimmune diseases and AD in their children.

RESULTS

A total of 8589 children with AD were matched with controls. One or more autoimmune disease was identified in 5.89% (506/8589) of mothers to AD children and 3.67% (315/8589) of fathers to AD children compared to 4.85% (4163/85 890) and 3.28% (2816/85 890) in parents of control children. Maternal autoimmune disease but not paternal autoimmune disease was associated with AD in the offspring (odds ratio [OR] 1.20 [95% confidence interval (CI) 1.20-1.32] and OR 1.08 [0.96-1.22], respectively), Two or more maternal autoimmune diseases, maternal dermatologic autoimmune disease and maternal digestive autoimmune disease were all also associated with AD development in her children (1.96 [95% CI 1.36-2.84], OR 1.60 [95% CI 1.24-2.07] and OR 1.24 [95% CI 1.06-1.45], respectively).

CONCLUSIONS

The risk of AD is influenced by many factors including atopy status and filaggrin gene mutations. In this matched case-control study, maternal autoimmune disease was associated with AD diagnosis in the offspring. Maternal dermatologic and digestive autoimmune diseases were most closely associated with subsequent AD diagnosis in the offspring.

Vitamin D receptor gene polymorphism, serum 25-hydroxyvitamin D levels, and risk of vitiligo: A meta-analysis

OBJECTIVES

To explore the relationship among the vitamin D receptor (VDR) gene polymorphisms, serum 25-hydroxyvitamin D levels, and vitiligo.

METHODS

Databases including PubMed, Cochrane Library, Ovid, Web of Science, CNKI, SinoMed, and Wanfang Data were systematically searched. The association was assessed using odds ratios (ORs), standard mean difference (SMD), and 95% confidence intervals (CIs). The statistical tests were performed using Review Manager 5.3.3.

RESULTS

We identified a total of 17 studies. The relationship between VDR gene polymorphisms (BsmI, ApaI, TaqI, and FokI), serum 25 (OH)D levels, and incidence of vitiligo was investigated. The results of this meta-analysis showed that the dominant genetic model (CC+AC vs AA, P = .007, OR = 1.41, 95% CI = 1.10-1.80), recessive genetic model (CC vs AC+AA, P = .01, OR = 4.10, 95% CI = 1.36-12.35), and allelic contrast model (C vs A, P = .005, OR = 1.87, 95% CI = 1.21-2.90) of VDR Apal locus increased the risk of vitiligo, and BsmI, TaqI, and FokI loci and the risk of vitiligo have no obvious correlation. Serum 25 (OH)D deficiency was positively associated with the incidence of vitiligo (P < .0001, SMD = -0.94, 95% CI = -1.39, -0.48).

CONCLUSION

This meta-analysis revealed that VDR Apal polymorphism increased the susceptibility risk of vitiligo, and there is a positive correlation between serum 25 (OH)D deficiency and the incidence of vitiligo.

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.