A novel IL36RN/IL1F5 homozygous nonsense mutation, p.Arg10X, in a Japanese patient with adult-onset generalized pustular psoriasis

Funding sources: this study was supported in part by a Grant‐In‐Aid for Scientific Research, (C) 23591617 (to K.S.) and (A) 23249058 (to M.A.) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Conflicts of interest: none declared. Madam, Generalized pustular psoriasis (GPP) is a rare but severe form of psoriasis that is sometimes life‐threatening. It is characterized by sudden, repeated episodes of high‐grade fever, generalized rash and disseminated pustules. The pathogenesis is unclear except for familial GPP, whose cause was recently identified as homozygous or compound heterozygous mutations in the IL36RN gene, also known as IL1F5, encoding the interleukin (IL)‐36 receptor antagonist (IL36RN).1, 2 IL36RN is primarily expressed in the skin,3 and is an antagonist of three cytokines that belong to the IL‐1 family: IL‐36α, IL‐36β and IL‐36γ, which are also known as IL‐1F6, IL‐1F8 and IL‐1F9, respectively.4, 5 These cytokines activate several proinflammatory signalling pathways, such as the nuclear factor‐κB and mitogen‐activated protein kinase pathways.6, 7