Bullous Pemphigoid and Human Leukocyte Antigen (HLA)-DQA1: A Systematic Review

Bullous pemphigoid (BP) is an autoimmune blistering disease that mainly affects the elderly. The human leukocyte antigen (HLA) system is believed to be one of the genetic factors involved in the development of BP. The connection between major histocompatibility complex class II, specifically HLA-DQA1, and BP remains inconclusive. The objective of this review is to find potential associations between BP and HLA-DQA1 alleles, identify the HLA-DQA1 alleles associated with an increased or decreased risk of developing BP, and highlight literature gaps for future research. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used to conduct a literature review. Databases used included PubMed/MEDLINE, Google Scholar, Embase, and Cochrane Library. Only studies written in English and conducted after 2000 that investigated the association between HLA-DQA1 and BP in human subjects were included. Odds ratios were calculated from the data provided in the studies, and a meta-analysis was conducted using Review Manager (The Cochrane Collaboration, London, United Kingdom) and MetaXL (EpiGear International Pty Ltd., Queensland, Australia) software. The systematic review found five eligible studies, and all were included in the meta-analysis. Results show an increased odds for BP in the HLA-DQA1*05:05 loci (odds ratio (OR) = 2.25; 95% confidence interval (CI) = 1.80, 2.80) and decreased odds for BP in the HLA-DQA1*02:01 loci (OR = 0.50; 95% CI = 0.36, 0.70). Further research is needed to confirm these findings and explore the potential clinical implications for personalized medicine approaches in BP patients.