CD40 and primary biliary cholangitis: A striking cluster of genes was associated with PBC, including LTBR (TNFR3), TNFRSF1A (TNFR1), NFKB1 (the p50 subunit of the classical NF-κB transcription factor complex), CHUK (NF-κB inhibitor kinase α) and IKBKB (NF-κB inhibitor kinase β), that all play roles in TNF and lymphotoxin alpha (LTA) signalling.