STAT3 and agammaglobulinemia: Other notable monogenic defects that can result in concurrent antibody deficiency and non-infectious complications include: signal transducer and activator of transcription 3 (STAT3) gain-of-function (GOF) germline mutations, inducible T-cell costimulatory (ICOS) deficiency, IKAROS deficiency, and an interferon regulatory factor-2 binding protein 2 (IRF2BP2) mutation.