Previous studies have reported <i>SLC20A2</i>, <i>PDGFB</i>, <i>PDGFRB</i>, <i>XPR1</i>, <i>MYORG</i>, <i>JAM2</i>, <i>CMPK2</i>, and <i>NAA60</i> as causative genes for familial PBC. The gene discussed is CMPK2; the disease is primary biliary cholangitis.