ADAD1 and psoriatic arthritis: The KIAA1109-TENR-IL2-IL21 region was first implicated in autoimmunity after a GWAS in T1D [13,22] and has since been associated, also with a genome-wide level of support, with celiac disease [16] and ulcerative colitis [14] and, with lower supporting evidence, with SLE, psoriatic arthritis, Graves' disease and juvenile idiopathic arthritis [13,17-19] (Table 1).