Flanagan SE, Haapaniemi E, Russell MA, Caswell R, Allen HL, De Franco E, McDonald TJ, Rajala H, Ramelius A, Barton J, Heiskanen K, Heiskanen-Kosma T, Kajosaari M, Murphy NP, Milenkovic T, Seppänen M, Lernmark A, Mustjoki S, Otonkoski T, Kere J, Morgan NG,
Monogenic causes of autoimmunity provide key insights into the complex regulation of the immune system. We report a new monogenic cause of autoimmunity resulting from de novo germline activating STAT3 mutations in five individuals with a spectrum of early-onset autoimmune disease, including type 1 diabetes. These findings emphasize the critical role of STAT3 in autoimmune disease and contrast with the germline inactivating STAT3 mutations that result in hyper IgE syndrome.