TYK2 and systemic lupus erythematosus: Genome wide association studies in SLE patients has demonstrated single nucleotide polymorphisms (SNPs) in loci near IFN related genes, in particular interferon regulatory factor 5 (IRF5), IRF7, IRF8, STAT4 and Tyk2, that are associated with the risk of developing SLE in adults (Sigurdsson et al., 2005; Graham et al., 2007).