Genetic Evidence for a Protective Role of Omega-3 Fatty Acids in Nummular Dermatitis

Background:The causal relationship between Omega-3 fatty acids and nummular dermatitis remains unclear.Methods:We performed a two-sample Mendelian randomization analysis using six independent SNPs associated with circulating Omega-3 levels. Summary statistics for nummular dermatitis were obtained from the FinnGen consortium. The inverse variance weighted method was the primary analysis, complemented by MR-Egger, weighted median, and mode-based approaches. Sensitivity analyses assessed pleiotropy and heterogeneity.Results:Higher genetically predicted Omega-3 levels were significantly associated with a reduced risk of nummular dermatitis (beta = -0.25, 95% CI: - 0.45 to - 0.06, P = 0.0111). The association was consistent across multiple MR methods, with no evidence of horizontal pleiotropy or significant heterogeneity.Conclusion:This study provides the first genetic evidence supporting a protective causal effect of Omega-3 fatty acids against nummular dermatitis, highlighting the potential of nutritional interventions for inflammatory skin diseases.