Exploring the link between gut microbiota and alopecia areata: a two‐sample Mendelian randomization analysis

Abstract Background While observational studies have suggested a link between gut microbiota diversity and alopecia areata (AA), the causal relationship remains unclear. Methods We leveraged data from the MiBioGen and FinnGen consortiums' Genome‐wide association studies (GWAS) encompassing gut microbiota ( n = 13,266) and AA ( n = 211,428) datasets. A comprehensive Mendelian randomization (MR) and reverse MR approach were employed, utilizing five statistical methods to evaluate causality. Sensitivity analyses were also conducted to corroborate the MR results. Results Inverse variance weighted (IVW) analysis indicated a protective effect against AA from Butyricimonas (OR = 0.37, 95% CI: 0.18–0.77, P = 0.01), Enterorhabdus (OR = 0.40, 95% CI: 0.16–0.95, P = 0.04), Eubacterium (xylanophilum group) (OR = 0.36, 95% CI: 0.15–0.84, P = 0.02), and Phascolarctobacterium (OR = 0.37, 95% CI: 0.15–0.91, P = 0.03), while Ruminococcaceae UCG003 posed as a risk factor (OR = 2.79, 95% CI: 1.27–6.14, P = 0.01). Reverse MR showed no significant causal link between AA and gut microbiota, with no significant heterogeneity or horizontal pleiotropy. Conclusions Our analysis suggests probable causality between certain gut microbiota and AA, shedding light on its pathogenesis and potential intervention strategies.