A wider range of mtDNA mutations, again mainly in complex I genes (MT-ND1, MT-ND5 and MT-ND6;http://www.mitomap.org/), have been instead associated with variably overlapping phenotypes of LHON, mitochondrial encephalomyopathy with stroke-like episodes (MELAS) and Leigh syndrome (LS) [2]. Here, MT-ND5 is linked to Leigh syndrome.