BACKGROUND: The aim of this paper is to describe the clinical features and molecular findings of a unique case of Leber's hereditary optic neuropathy (LHON)/mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) overlap syndrome presenting as nonischemic central retinal vein occlusion (CRVO). METHODS: An 11-year-old Chinese girl presented with sudden onset of bilateral blurred vision. The clinical history, imaging studies, and molecular analysis results were reviewed. The PubMed and OVID databases were used for literature review. RESULTS: Nonischemic CRVO in the subject's right eye and tortuosity of small and medium-sized retinal arterioles in the left eye were found at initial presentation. Bilateral optic disc pallor was then noted with recovery of CRVO. Severe headache and several stroke-like episodes occurred subsequently, with elevated lactate levels in serum and cerebrospinal fluid. LHON/MELAS overlap syndrome was diagnosed, and mitochondrial DNA sequencing revealed G13513A heteroplasmic mutation. Vision was 20/30 in the right eye and 20/800 in the left eye at the last visit. CONCLUSIONS: Mitochondrial DNA G13513A mutation can cause LHON/MELAS overlap syndrome. Nonischemic CRVO is a rare manifestation of LHON/MELAS. Atypical findings in cases of LHON should raise the suspicion of overlap syndrome or other mitochondrial diseases.
BACKGROUND: The aim of this paper is to describe the clinical features and molecular findings of a unique case of Leber's hereditary optic neuropathy (LHON)/mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) overlap syndrome presenting as nonischemic central retinal vein occlusion (CRVO). METHODS: An 11-year-old Chinese girl presented with sudden onset of bilateral blurred vision. The clinical history, imaging studies, and molecular analysis results were reviewed. The PubMed and OVID databases were used for literature review. RESULTS: Nonischemic CRVO in the subject's right eye and tortuosity of small and medium-sized retinal arterioles in the left eye were found at initial presentation. Bilateral optic disc pallor was then noted with recovery of CRVO. Severe headache and several stroke-like episodes occurred subsequently, with elevated lactate levels in serum and cerebrospinal fluid. LHON/MELAS overlap syndrome was diagnosed, and mitochondrial DNA sequencing revealed G13513A heteroplasmic mutation. Vision was 20/30 in the right eye and 20/800 in the left eye at the last visit. CONCLUSIONS: Mitochondrial DNA G13513A mutation can cause LHON/MELAS overlap syndrome. Nonischemic CRVO is a rare manifestation of LHON/MELAS. Atypical findings in cases of LHON should raise the suspicion of overlap syndrome or other mitochondrial diseases.