MT-ND4 and cardiomyopathy: For the mtDNA-subnetwork, mutations of MT-ND1, MT-ND2, MT-ND3, MT-ND4, MT-ND4L, MT-ND5, MT-ND6, MT-CO1, MT-CO2, MT-CO3, MT-ATP6, MT-ATP8, and MT-CYB have been identified in cardiomyopathy patients [25,26,27,28].