Rigorous sensitivity analyses including MR-Egger, weighted median and MR-PRESSO were conducted to ensure the reliability of the causal estimate.<h4>Results</h4>We identified two immunophenotypes associated with an increased risk of allergic purpura: HLA-DR on CD14 + CD16- monocyte (OR: 1.2379; 95% CI: 1.0612-1.4440; P = 0.0066) and CD11b on basophil (OR: 1.2973; 95% CI: 1.0905-1.5433; P = 0.0033). The gene discussed is ITGAM; the disease is Henoch-Schoenlein purpura.