SLC4A2 knockdown experiments in mammalian cholangiocytes have implicated AE2 as the main effector in biliary HCO3− secretion4 and furthermore, SLC4A2 knockdown mice exhibited typical symptoms of primary biliary cholangitis (PBC), including generation of antimitochondrial antibodies (AMA), portal inflammation and damaged interlobular bile ducts9–11. This evidence concerns the gene SLC4A2 and primary biliary cholangitis.