This study aimed to explore the role of additional mitochondrial DNA (mtDNA) variants in the development of Leber hereditary optic neuropathy (LHON) by screening the entire mitochondrial genome in individuals who had previously tested negative for the three common mtDNA variants: m.3460G > A (MT-ND1), m.11778G > A (MT-ND4), and m.14484 T > C (MT-ND6), by conventional Sanger sequencing. This evidence concerns the gene MT-ND4 and Leber hereditary optic neuropathy.