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 tRNALys 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 tRNALys 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 TψC 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 tRNALys alterations may play a specific role in the pathogenesis of MERRF syndrome.
|Original language||English (US)|
|Number of pages||5|
|Journal||American journal of human genetics|
|State||Published - 1992|
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