MT-ND4 and age-related macular degeneration: Common mtDNA pathogenic variants identified in AMD include changes in the MT-ND2 (m.4917A>G), MT-ND4 (m.11812A>G, m.11778G>A), MT-ND6 (m.14233A>G), and MT-ATP6 genes (m.8993T>G), which are involved in the function of the electron transport chain [89,90].