As increased DPP4 serum activity has been found in multiple hepatological diseases, such as hepatocellular carcinoma, NASH or cirrhosis, with DPP4 showing ubiquitous expression in bile ducts and adjacent hepatocytes17,47,48we deem our observations to be unspecific to BA, but rather interpret the DPP4 activity as a sign of a general activation of the immune system in the setting of hepatic inflammation. Here, DPP4 is linked to glycogen storage disease VI.