TYK2-deficient human T cells exhibit impaired responses to IL-12, IL-23, IFN-α, and IL-1042 whereas Tyk2 dysfunction has been related to the prevention of immune- mediated inflammatory diseases including psoriasis, psoriatic arthritis and vitiligo43,44 without immunodeficiency.45 In SLE, TYK2 is implicated in the increased autophagy activity by B cells46 and NPSLE.47 Here, TYK2 is linked to psoriatic arthritis.