NDUFA9 and Alzheimer disease: The subunits of complex I including NDUFA1, NDUFA2, NDUFA4, NDUFA5, NDUFA9, NDUFA10, NDUFB3, NDUFB6, NDUFB8, NDUFB11, NDUFS4 and NDUFS7 were significantly low abundant in early-onset AD individuals (Fig. 3, lower panel).