APP and Cholestatic liver disease: In addition, the authors found altered expression of several genes involved in amyloid-β precursor protein (APP) processing and the Alzheimer’s secretase signaling pathway.37 Other authors found amyloid-β expression increased in the plasma and livers of infants with BA38 and based on the liver APP gene expression suggested the utility of APP as a biomarker in conjunction with other liver function parameters for BA and non-BA cholestatic liver diseases.39