[Positive diagnosis of Leber's hereditary optic neuropathy using molecular genetics].
INTRODUCTION: Leber's hereditary optic neuropathy (LHON) is a bilateral optic atrophy, more common in males than in females. No specific clinical feature or biologic test exists to evidence LHON. We report here the case of a man affected with a nonfamilial bilateral optic atrophy, whose diagnostic remained uncertain for 17 years. PATIENT AND METHODS: This patient was hospitalized at the age of 27 in order to establish diagnosis. He had an ophthalmologic examination once a year. He was also affected with chronic renal failure. Detection of the G to A mutation at position 11778 of the DNA was assessed by restriction enzyme digestion of amplified genomic DNA. RESULTS: The 11778 mitochondrial DNA mutation was evidenced, in homoplasmic condition in white blood cells. DISCUSSION: Molecular biology allows to substantiate the diagnosis of LHON and is relatively easy and cheap. Assessment of mitochondrial DNA provides a useful diagnostic tool for nonfamilial or atypical cases of LHON.