Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the case of a 19-year-old Chinese female harboring the m.3291T>C mutation in the MT-TL1 gene encoding the mitochondrial transfer RNA for leucine. She presented with a complex phenotype characterized by progressive cerebellar ataxia, frequent myoclonus seizures, recurrent stroke-like episodes, migraine-like headaches with nausea and vomiting, and elevated resting lactate blood level. It is known that the myoclonus epilepsy with ragged-red fibers (MERRF) is characterized by cerebellar ataxia and myoclonus epilepsy, while that the mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is characterized by recurrent stroke-like episodes, migraine-like headaches, and elevated resting lactate blood level. So the patient's clinical manifestations suggest the presence of a MERRF/MELAS overlap syndrome. Muscle biopsy of the patient showed the presence of numerous scattered ragged-red fibers, some cytochrome c oxidase-deficient fibers, and several strongly succinate dehygrogenase-reactive vessels, suggestive of a mitochondrial disorder. Direct sequencing of the complete mitochondrial genome of the proband revealed no mutations other than the T-to-C transition at nucleotide position 3291. Restriction fragment length polymorphism analysis of the proband and her family revealed maternal inheritance of the mutation in a heteroplasmic manner. The analysis of aerobic respiration and glycolysis demonstrated that the fibroblasts from the patient had mitochondrial dysfunction. Our results suggest that the m.3291T>C is pathogenic. This study is the first to describe the m.3291T>C mutation in association with the MERRF/MELAS overlap syndrome.
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PMID:MERRF/MELAS overlap syndrome due to the m.3291T>C mutation. 2433 29

Myoclonic epilepsy associated with ragged red fibers (MERRF) is a rare mitochondrial disorder. Diagnostic criteria for MERRF include typical manifestations of the disease: myoclonus, generalized epilepsy, cerebellar ataxia and ragged red fibers (RRF) on muscle biopsy. Clinical features of MERRF are not necessarily uniform in the early stages of the disease, and correlations between clinical manifestations and physiopathology have not been fully elucidated. It is estimated that point mutations in the tRNALys gene of the DNAmt, mainly A8344G, are responsible for almost 90% of MERRF cases. Morphological changes seen upon muscle biopsy in MERRF include a substantive proportion of RRF, muscle fibers showing a deficient activity of cytochrome c oxidase (COX) and the presence of vessels with a strong reaction for succinate dehydrogenase and COX deficiency. In this review, we discuss mainly clinical and laboratory manifestations, brain images, electrophysiological patterns, histology and molecular findings as well as some differential diagnoses and treatments.
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PMID:When should MERRF (myoclonus epilepsy associated with ragged-red fibers) be the diagnosis? 2533 34


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