The MT-ND1 and MT-ND5 genes are mutational hotspots for Chinese families with clinical features of LHON but lacking the three primary mutations

► Families with suspected LHON have a high penetrance rate. ► ND1 and ND5 are mutational hotspots for Chinese families with suspected LHON. ► Mutations m.3736G>A and m.10680G>A may be pathogenic.