IRF5 and rheumatoid arthritis: Among the IFN-I signaling pathway genes, a SNP (rs4731532) had an ir-QTL effect for an IRF5 isoform (IRF5_1, unannotated in GENCODE) and was co-localized with GWAS signals linked to a range of autoimmune diseases, including systemic sclerosis, Sjögren’s syndrome, and RA (Figure 6D).