A new mtDNA mutation in the tRNA(Lys) gene associated with myoclonic epilepsy and ragged-red fibers (MERRF). |
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| Authors: | G Silvestri C T Moraes S Shanske S J Oh and S DiMauro |
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| Institution: | H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Columbia University College of Physicians and Surgeons, New York, NY 10032. |
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| Abstract: | Myoclonic epilepsy with ragged-red fibers (MERRF) has been associated with an A--G transition at mtDNA nt 8344, within a conserved region of the tRNA(Lys) gene. Although the 8344 mutation is highly prevalent in patients with MERRF, it is not observed in 10%-20% of the cases, suggesting genetic heterogeneity. We have sequenced the tRNA(Lys) gene of five MERRF patients lacking the common 8344 mutation. One of these showed a novel T-->C transition at nucleotide position 8356, disrupting a highly conserved base pair in the T psi C stem. The mutant mtDNA population was essentially homoplasmic in muscle but was heteroplasmic in blood (47%). Neither 20 patients with other mitochondrial diseases nor 25 controls carried this mutation. These findings suggest that tRNA(Lys) alterations may play a specific role in the pathogenesis of MERRF syndrome. |
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