APBB1 and Alzheimer disease: Amyloid precursor protein (APP) a highly expressed transmembrane protein in the AD brain, and a neuronal adapter Fe65 binds to APP intracellular domain (AICD), after the proteolytic cleavage of APP by β-secretase and γ-secretase.22 The Fe65/APP complex is then translocated to the nucleus to initiate gene transcription, the exact function of which is still unclear.