MT-ND5 and Leber hereditary optic neuropathy: However within that clinical heterogeneity, at certain points in the course of disease, several distinct clinical syndromes associated with mutations in the MT-ND5 gene were clearly discernible: early onset LS (38%), late childhood/early adulthood-onset LS/MELAS overlap syndrome (13%) and LHON (4%) (not previously recognized in association with the m.13094T>C mutation).