First-time screening for autoimmune liver disease revealed smooth muscle antibodies (SMA)+++, an antinuclear antibody (ANA) titer of 1:320, antimitochondrial antibodies (AMA)++, an anti-M2 antibody titer of 1:1140, and a total serum IgM level of 8.5 g/L (0.3-2.4 g/L), consistent with autoimmune hepatitis/primary biliary cirrhosis (AIH/PBC) overlap syndrome, which is a rare condition in which patients have features of both diseases. This evidence concerns the gene CD40LG and primary biliary cholangitis.