IL12RB2 and primary biliary cholangitis: GWASs have also identified 44 non-HLA PBC predisposition loci [121] A significant association has been shown between PBC and genetic variants of interleukin (IL)12A, IL12RB2, interferon regulatory factor 5 (IRF5), transportin 3 (TNPO3), and, finally, transcription factor Spi-B (SPIB) encoding a transcription factor involved in B-cell receptor and T-cell signaling [125].