The p.E105K mutation promoted the apoptotic process, evidenced by increasing ratios of annexin V+ cells, elevated releases of cytochrome c into cytosol, and increased levels in caspases-9 in both MT cell lines bearing the p.E105K mutation and knockdown cell lines, as in the cases of cells bearing the LHON-associated mtDNA mutations (15, 30, 60–62). This evidence concerns the gene CASP9 and Leber hereditary optic neuropathy.