A 37-year-old woman presented with proximal limb weakness, an unstable gait, tiredness and paroxysmal jitters. Neurological examination showed decreased deep tendon reflexes and positive signs indicating damage to the cerebellum. The patient's children reported no symptoms but were found to have the mitochondrial 3302A>G mutation in the mitochondrially encoded tRNA-Leu (UUA/G) 1 gene. The patient presented with increased blood lactic acid and lactic acid dehydrogenase levels, myopathy-related limb muscle electromyographic activities, ragged red fibers (RRFs), cytochrome oxidase-negative muscle fibers and mitochondrial 3302A>G mutation. Inverted lactic acid peaks in the basal ganglia, an atrophied cerebellum and multiple electroencephalographic spike waves were also observed. Therefore, myoclonic epilepsy with RRFs syndrome with the 3302A>G mutation was considered.
Keywords: MT-TL1 gene; gene mutation; mitochondrial DNA; mitochondrial encephalomyopathy; myoclonic epilepsy with ragged red fibers syndrome.
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