Deficiencies in type 17 immunity associated with susceptibility to widespread chronic dermatophytosis have been reported in patients with ATLL (67), autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) (72), Dectin-1 mutations (39), loss-of-function mutations in STAT3 (62), autosomal gain-of-function mutations in STAT1 (96, 97), and anti-IL-17 antibody treatment (secukinumab) (73, 98). Here, IL17A is linked to adult T-cell leukemia/lymphoma.