ENPP2 and primary biliary cholangitis: PBC and PSC patients had increased ATX activity compared to healthy controls (10.2 ± 4.4 vs. 7.3 ± 3.4 vs. 2.8 ± 1.4 nmol mL−1 min−1 in patients with PBC, PSC and controls, respectively; P < 0.0001 for all; Fig. 1).