TYK2 and psoriasis: Multiple genetic psoriasis susceptibility loci affect different parts of the Th1 signaling pathway, including IL-12B (coding for the p40 subunit of IL-12) [100], tyrosine kinase 2 (TYK2) [101], ZC3H12C (transcript involved in macrophage activation) [89], STAT5A, STAT5B, and ILF3 (interleukin enhancer-binding factor 3) [102].