In 2010, two independent studies reported that, irrespective of age, >90% of APS-1 patients tested had high serum titers of neutralizing IgG auto-Abs against at least one of the IL-17 cytokines (IL-17A, IL-17F, IL-22; Table 1, Figure 1). Here, IL17A is linked to autoimmune polyendocrine syndrome type 1.