MERRF-Like Phenotype Associated with a Rare Mitochondrial tRNA^Ile Mutation (m.4284 G>A)

Abstract

Nearly all patients affected by myoclonic epilepsy with ragged-red fibres (MERRF) harbour a mutation in the mitochondrial transfer RNA^Lys gene. We report on an 8-year-old girl with clinical and diagnostic features of MERRF. After excluding one of the common mutations associated with MERRF, a complete sequence analysis of the mitochondrial genome revealed an m.4284 G>A mutation in the mitochondrial transfer RNA^Ile gene. This mutation has only once been described in a family with variable clinical symptoms, but has not yet been linked to MERRF. This case extends the mutational spectrum associated with the MERRF phenotype, and demonstrates the importance of performing a comprehensive mutational analysis in patients with suspected mitochondrial disease when common mutations have been ruled out.

Key words

mitochondrial disorder - ragged-red fibres - progressive myoclonic epilepsy - MERRF - mtDNA-mutation

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