Association between inflammatory bowel disease and rosacea: A bidirectional two-sample Mendelian randomization study

To the Editor: Epidemiological studies have implied a potential connection between rosacea and inflammatory bowel disease (IBD).1 However, epidemiological studies cannot completely rule out distortions. Mendelian randomization (MR) is a method used to determine the causation and limit confounding biases using genetic variants that are substantially correlated with exposure as instrumental variables (Fig 1).2 We performed an MR analysis on genome-wide association studies (GWAS) data obtained from two samples to detect whether there is a potential bidirectional causal relationship between rosacea and IBD.