IL9 and psoriasis vulgaris: Reversely, we identified causal effects of the onset of psoriasis vulgaris on 11 circulating cytokine levels including IL-1ra, IL-5, CTACK, MIG, VEGF, IL-8, IL-9, IL-13, IL-12p70, TNF-α, and IL-2 at p < 0.05 in at least one of the 3 MR methods based on MR results from Supplementary Table S4.