Vitiligo and Rise in Blood Pressure - a Case-Control Study in a Referral Dermatology Clinic in Southern Iran

Identification of TNF-α as Major Susceptible Risk Locus for Vitiligo: A Systematic Review and Meta-Analysis Study in the Asian Population

INTRODUCTION

Vitiligo is a common depigmentation disorder characterized by defined white patches on the skin and affecting around 0.5% to 2% of the general population. Genetic association studies have identified several pre-disposing genes and single nucleotide polymorphisms (SNPs) for vitiligo pathogenesis; nonetheless, the reports are often conflicting and rarely conclusive. This comprehensive meta-analysis study was designed to evaluate the effect of the risk variants on vitiligo aetiology and covariate stratified vitiligo risk in the Asian population, considering all the studies published so far.

METHODS

We followed a systematic and comprehensive search to identify the relevant vitiligo-related candidate gene association studies in PubMed using specific keywords. After data extraction, we calculated, for the variants involved, the study-level unadjusted odds ratio, standard errors, and 95% confidence intervals by using logistic regression with additive, dominant effect, and recessive models using R software package (R, 3.4.2) "metafor." Subgroup analysis was performed using logistic regression (generalized linear model; "glm") of disease status on subgroup-specific genotype counts. For a better understanding of the likely biological function of vitiligo-associated variant obtained through the meta-analysis, in silico functional analyses, through standard publicly available web tools, were also conducted.

RESULTS

Thirty-one vitiligo-associated case-control studies on eleven SNPs were analysed in our study. In the fixed-effect meta-analysis, one variant upstream of TNF-α gene: rs1800629 was found to be associated with vitiligo risk in the additive (p = 4.26E-06), dominant (p = 1.65E-7), and recessive (p = 0.000453) models. After Benjamini-Hochberg false discovery rate (FDR) correction, rs1800629/TNF-α was found to be significant at 5% FDR in the dominant (padj = 1.82E-6) and recessive models (padj = 0.0049). In silico characterization revealed the prioritized variant to be regulatory in nature and thus having potential to contribute towards vitiligo pathogenesis.

CONCLUSION

Our study constitutes the first comprehensive meta-analysis of candidate gene-based association studies reported in the whole of the Asian population, followed by an in silico analysis of the vitiligo-associated variant. According to the findings of our study, TNF-α single nucleotide variant rs1800629G>A has a risk association, potentially contributing to vitiligo pathogenesis in the Asian population.

Prevalence and burden of vitiligo in Africa, the Middle East and Latin America

Vitiligo is a common chronic autoimmune disorder characterized by skin and hair depigmentation that affects 0.5%-2.0% of the global population. Vitiligo is associated with diminished quality of life (QoL) and psychosocial burden. The burden of vitiligo may vary based on skin tone and cultural differences as well as geographical variations in disease awareness, societal stigma, healthcare systems and treatment options. Data on the burden and management of vitiligo in Africa, the Middle East and Latin America are scarce. Literature searches using terms covering vitiligo in Africa, the Middle East and Latin America were conducted using PubMed to identify relevant publications that focused on disease prevalence and burden, QoL and psychosocial impact and disease management between 2011 and 2021. Most of the reviewed studies were conducted in the Middle East, and most Latin American studies were from Brazil. Most studies involved small patient numbers and may not be generalizable. Reported prevalence of vitiligo ranged from 0.18% to 5.3% in Africa and the Middle East, and from 0.04% to 0.57% in Latin America. In several studies, prevalence was higher among female participants. Generally, non-segmental vitiligo was the dominant clinical variant identified and the age at onset varied widely across studies. Common comorbidities include autoimmune diseases such as Hashimoto's thyroiditis, alopecia areata and diabetes. Few treatment guidelines exist in these regions, with the exceptions of guidelines published by the Brazilian and Argentinian Societies of Dermatology. There is a clear unmet need for large epidemiological studies with uniform methodology to accurately ascertain the true prevalence of vitiligo in Africa, the Middle East and Latin America. Additional data on vitiligo burden and management in Africa and Latin America are also needed, along with local disease management guidelines that consider genetic variation, psychosocial burden and socioeconomic diversity in all 3 regions.

Vitiligo and insulin resistance as a component of metabolic syndrome: an analysis

There have been many studies on the association between vitiligo and metabolic syndrome, while only few scientific papers on vitiligo and insulin resistance. In recent years, there have been significant developments in research to trace and understand the aetiology of both conditions. In this article we have analysed pathophysiological mechanisms and the association of insulin resistance (as a component of metabolic syndrome) and vitiligo.

Comorbidities in Patients with Vitiligo: A Systematic Review and Meta-Analysis

Vitiligo has been reported to be associated with a variety of diseases, but it has not been systematically reviewed. Therefore, we aimed to identify prevalent diseases in patients with vitiligo and quantify their associations compared with those in healthy controls. A comprehensive search of MEDLINE and EMBASE from the inception to June 2022 was conducted. Observational studies on prevalent diseases in patients with vitiligo compared with those in healthy controls were included, whereas studies limited to pediatrics or providing only laboratory results were excluded. A total of 78 studies were eligible for analyses. Patients with vitiligo showed higher risks of having comorbid autoimmune and connective tissue diseases, including alopecia areata (OR = 2.63, 95% confidence interval [CI] = 2.50‒2.78), discoid lupus erythematosus (OR = 2.54, 95% CI = 1.74‒3.72), Sjogren's syndrome (OR = 2.50, 95% CI = 1.98‒3.16), myasthenia gravis (OR = 2.30, 95% CI = 1.74‒3.02), systemic lupus erythematosus (OR = 1.96, 95% CI = 1.52‒2.52), and rheumatoid arthritis (OR = 1.82, 95% CI = 1.55‒2.15). Thyroid diseases, diabetes mellitus, metabolic syndrome, sensorineural hypoacusis, and ophthalmic abnormalities were also more prevalent in patients with vitiligo. In conclusion, vitiligo is associated with various systemic diseases. Physicians should evaluate and manage potential comorbid conditions in patients with vitiligo.

Vitiligo and Metabolic Syndrome: Systematic Review and Meta-Analysis

BACKGROUND

Metabolic syndrome (MetS) has been associated with various skin conditions including vitiligo. However, the association between these 2 conditions has yet to be determined by quantitative meta-analysis.

OBJECTIVE

The aim of this paper was to determine the association between vitiligo and metabolic syndrome via systematic review and meta-analysis.

METHODS

A systematic literature search of Pubmed, Embase, Cochrane, and Web of Science was performed for all published literature prior to August 16, 2020. Case control and prospective cross-sectional studies analyzing the association between vitiligo and MetS were included in this review. The primary outcome measures include the type of vitiligo, diagnostic criteria for MetS, components of MetS (waist circumference, blood pressure, triglycerides, fasting glycemic index, and high-density lipoprotein cholesterol), low-density lipoprotein cholesterol levels, and BMI. A meta-analysis was performed to evaluate the prevalence and association of MetS in patients with vitiligo.

RESULTS

A total of 6 studies (n=734 participants) meeting eligibility criteria were included for systematic review and meta-analysis. The pooled prevalence of MetS in patients with vitiligo was (0.296, 95% CI 0.206, 0.386; P<.001). Patients with vitiligo were no more likely to develop MetS compared to control patients (odds ratio 1.66, 95% CI 0.83, 3.33; P=.01). A leave-one-out sensitivity analysis showed a significant association between MetS and vitiligo (P<.001). Significant elevations in fasting glycemic index (mean difference 5.35, 95% CI 2.77, 7.93; P<.001) and diastolic blood pressure (mean difference 1.97, 95% CI 0.02, 3.92; P=.05) were observed in patients with vitiligo compared to control patients.

CONCLUSIONS

The association between vitiligo and metabolic syndrome carries important clinical implications. Dermatologists and other multidisciplinary team members should remain vigilant when treating this patient population in order to prevent serious cardiovascular complications that may arise as a result of metabolic disease.

Vitiligo: The Association With Metabolic Syndrome and the Role of Simvastatin as an Immunomodulator

Vitiligo is an autoimmune condition primarily affecting the skin where there is destruction of melanocytes characterized by pinkish-white patches on the skin. It is associated with other autoimmune diseases such as thyroid disease, rheumatoid arthritis, diabetes mellitus, and metabolic syndrome. Metabolic syndrome is a constellation of disorders including insulin resistance, hypertension, dyslipidemia, and obesity, and is considered a leading cause of cardiovascular morbidity. Simvastatin is a potent hypolipidemic drug that also possesses immunomodulating properties and is a common drug used in dyslipidemia and cardiovascular diseases. This study aimed to assess the association between vitiligo and metabolic syndrome and explore the immunomodulating properties of simvastatin for use in vitiligo. We reviewed various articles from PubMed, ResearchGate, and Google Scholar using different keywords and Medical Subject Headings and finalized 33 studies to be used in our review. The articles selected showed a positive association between vitiligo and metabolic syndrome or one of the component diseases of metabolic syndrome. The benefits of using simvastatin were also addressed by few articles attributing to its antioxidant and immunomodulating effect. However, there was no concrete explanation justifying the association between vitiligo and metabolic syndrome due to a limited number of studies and smaller sample size. Large-scale clinical trials should be conducted to evaluate the use of simvastatin as an immunomodulator in vitiligo to prevent possible metabolic complications.