STAT4 and systemic sclerosis: Genetic associations that predispose for development of SSc-ILD specifically, have been found in interferon regulatory factor 5 (IRF5), signal transducer and activator of transcription 4 (STAT4), DNAX accessory molecule 1 (CD226) and interleukin-1 receptor-associated kinase-1 (IRAK1) (63).