Genomic Correlation, Shared Loci, and Causal Relationship Between Bullous Pemphigoid and Atopic Dermatitis: A Large‐Scale Genome‐Wide Cross‐Trait Analysis

Abstract

ABSTRACT Background Bullous pemphigoid (BP) and atopic dermatitis (AD) are currently thought to be tightly related, yet studies of the mechanisms of co‐morbidities are lacking. Methods We obtained GWAS data for BP (N = 376,274) and AD (N = 796,661) from the Finnish Genetic Research Program dataset and the UK Biobank, separately. Then, the following four analyses were performed: (1) cross‐trait linkage disequilibrium score regression (LDSC) to assess the genetic correlation between BP and AD, (2) cross‐phenotype association analysis (CPASSOC) to identify multiple effector loci shared by BP and AD, (3) transcriptome‐wide association study (TWAS) to determine whether their cross‐organizational expression patterns share genes with a common biological mechanism of relevance, and (4) bidirectional Mendelian randomization (MR) analysis to assess bidirectional causal effects of BP and AD. Results We found a positive genetic association between BP and AD (rg = 0.5476, p = 0.0495) as well as identified four pleiotropic loci and 59 common genes affecting BP and AD. Bidirectional MR analysis suggested that BP promotes the risk of AD. Conclusions We revealed a genetic link between BP and AD, which is associated with biological pleiotropy and causality. Awareness of the association between BP and AD helps dermatologists manage patients with these illnesses.

Keywords

• atopic dermatitis
• bullous pemphigoid
• co‐morbidities
• cross‐trait meta‐analysis
• genome‐wide genetic correlation analysis
• mendelian randomization