STAT4 and systemic sclerosis: For the type-I interferon signaling pathway, some researches have revealed that the type-I interferon signaling pathway-related genes, such as STAT4 and IRF5, are associated with a significant risk of SSc occurrence (Dieude et al., 2009; Gourh et al., 2009; Ito et al., 2009; Rueda et al., 2009).