RESUMEN
BACKGROUND: Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder with optic nerve atrophy. Although there are no other associated neurological abnormalities in most cases of LHON, cases of "LHON plus" have been reported. CASE REPORT: The proband was a 37-year-old man who had visual and gait disturbances that had first appeared at 10 years of age. He showed horizontal gaze palsy, gaze-evoked nystagmus, dysarthria, and cerebellar ataxia. Brain and orbit MRI disclosed atrophy of the optic nerve and cerebellum, and degenerative changes in the bilateral inferior olivary nucleus. Mutational analyses of mitochondrial DNA identified the coexistence of heteroplasmic G11778A and homoplasmic T3394C mutations. CONCLUSIONS: These results suggest that the combination of G11778A and T3394C mutations leads to an atypical LHON phenotype.