Both autoimmune polyendocrinopathy‐candidiasis‐ectodermal dystrophy (APECED) and the rare thymoma patients with chronic mucocutaneous candidiasis (CMC) have neutralizing autoantibodies to Th17 cytokines and significant defects in production of IL‐22 and IL‐17F by their T cells. Here, IL17F is linked to chronic mucocutaneous candidiasis.