Résumé :
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The mitochondrial DNA point mutation T8993G has been associated with NARP and maternally inherited Leigh syndrome (MILS). Usually there is a correlation between the percentage of mutated mtDNA and clinical severity. Objectives: The aim is to show different clinic phenotypes, multisystemic disorders and different percentage to mtDNA mutation and heteroplasmy in the same family with diagnosis of NARP and others members maternally inherited with Leigh‘s syndrome (MILS). Material and Methods: We present four members of an Argentinean family with mtDNA T8993G point mutation who had diverse clinical manifestations and different percentage of mtDNA mutation. Diagnosis was established according to modified Walker Criteria based in clinical, functional, molecular, metabolic parameters and was followed for 11 years. Case 1: IF. Female 14 years, early onset, seizures at 8 months, motor milestones delayed, nasal speech, swallowing difficulties, ataxia, and neuropathy. CT scan showed lesions in basal ganglia and atrophy of the brain. Case 2: NF. Female 13 years old, presented sudden severe weakness at 5years old, fever and lethargy. CT scan showed hypointense signal in basal ganglia. Case 3: BA. Female 40 years old, presented rheumatoid arthritis, neuropathy. Case 4: LF. Female 18 years old, presented convergent strabismus and abnormal movements at 15 years old. Molecular test showed mtDNA T8993G point mutation. They did not show cardiological disturbances. Results: The percentage of mtDNA T8993G point mutation in blood was: Case 1:74%, in muscle biopsy 92%. Sural nerve biopsy showed axonal degeneration. Case 2: 86%. Case 3: 36%. Case 4: show mtDNA T8993G point mutation. CONCLUSION: Phenotypic heterogeneity in this family show both Leigh’s and NARP phenotypes. High mitochondrial DNA T8993G mutation is not always associated with typical features and severity of Leigh’s and NARP syndromes. There was no correlation in our patients between proportion of mutant mitochondrial DNA in blood and clinical features. Acknowledgments: to Dr. Bindhoff, Middlesbrough General Hospital. United Kingdom. Dra. Lei Li, Moelcular Laboratory , Childrens Hospital Los Angeles. USA. Buenos Aires. Argentina: Dra. A. Taratutto, FLENI, Dra.Marcela Garcia Alvarez.
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