The MTATP6 m.8993 T > G/C variant, that damages the F0 portion of ATPase [44], is associated to Maternally Inherited Leigh Syndrome (MILS) and to Neuropathy, Ataxia and Retinititis Pigmentosa (NARP) syndrome with basically the heteroplasmy rates defining the phenotype. This evidence concerns the gene MT-ATP6 and maternally-inherited Leigh syndrome.