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September 1993

Ocular Clinicopathologic Study of the Mitochondrial Encephalomyopathy Overlap Syndromes

Author Affiliations

From the Eye Pathology Laboratory, Wilmer Institute, and Department of Pathology (Drs Chang, Walker, and Green and Ms de la Cruz), the Center for Hereditary Eye Diseases, Wilmer Institute (Dr Maumenee), and the Department of Neurology (Dr Johns), The Johns Hopkins Medical Institutions, Baltimore, Md. Dr Walker is now with the Ophthalmology Department, University of British Columbia, Vancouver.

Arch Ophthalmol. 1993;111(9):1254-1262. doi:10.1001/archopht.1993.01090090106028

Recent advances in molecular genetics have led to a better understanding of mitochondrially inherited diseases. Mitochondrial encephalomyopathy overlap syndrome is one such group of diseases in which ocular abnormalities are frequently manifest. The authors describe the clinical, molecular genetic, and pathologic findings of two patients with the mitochondrial encephalomyopathy overlap syndrome. The patients shared a similar clinical course with features overlapping the three traditionally distinct clinical phenotypes (the Kearns-Sayre syndrome; the syndrome of mitochondrial encephalopathy, lactic acidosis, and stroke [MELAS], and the syndrome of myoclonus, epilepsy, and ragged red fibers [MERRF]). The patients had identical mitochondrial DNA mutations (at nucleotide position 3243) and had similar ultrastructural abnormalities, including abundant enlarged mitochondria with "whorled" and "tubular" cristae. These abnormal mitochondria appeared to be preferentially distributed in cells with high metabolic activity (retinal pigment epithelium, corneal endothelium, and extraocular muscles).