OBJECTIVE: To assess whether impaired energy metabolism in skeletal muscle is a hallmark feature of patients with dominant optic atrophy due to several different mutations in the OPA1 gene. DESIGN: We used phosphorus 31 magnetic resonance spectroscopy to assess calf muscle oxidative metabolism in subjects with molecularly defined dominant optic atrophy carrying different mutations in the OPA1 gene. In a subset of patients, we also evaluated serum lactate levels after exercise and muscle biopsy results for histology and mitochondrial DNA analysis. SETTING: University neuromuscular and neurogenetics and magnetic resonance imaging units. PATIENTS: Eighteen patients with dominant optic atrophy were enrolled from 8 unrelated families, 7 of which carried an OPA1 mutation predicted to induce haploinsufficiency and 1 with a missense mutation in exon 27. Fifteen patients had documented optic atrophy. MAIN OUTCOME MEASURES: Presence of skeletal muscle mitochondrial oxidative phosphorylation dysfunction as assessed by phosphorus 31 magnetic resonance spectroscopy, serum lactate levels, and histological and mitochondrial DNA analysis. RESULTS: Phosphorus 31 magnetic resonance spectroscopy showed reduced phosphorylation potential in the calf muscle at rest in patients with an OPA1 mutation (-24% from normal mean; P = .003) as well as a reduced maximum rate of mitochondrial adenosine triphosphate synthesis (-36%; P < .001; ranging from -28% to -49% in association with different mutations). In 4 of 10 patients (40%), the serum lactate level after exercise was elevated. Only 2 of 5 muscle biopsies, from the 2 patients with a missense mutation, showed slight myopathic changes. Low levels of mitochondrial DNA multiple deletions were found in all muscle biopsies. CONCLUSIONS: Defective oxidative phosphorylation in skeletal muscle is a subclinical feature of patients with OPA1-related dominant optic atrophy, indicating a systemic expression of the OPA1 defect, similar to that previously reported for Leber hereditary optic neuropathy due to complex I dysfunction. This defect of oxidative phosphorylation does not appear to depend on the low amounts of mitochondrial DNA multiple deletions detected in muscle biopsies.
OBJECTIVE: To assess whether impaired energy metabolism in skeletal muscle is a hallmark feature of patients with dominant optic atrophy due to several different mutations in the OPA1 gene. DESIGN: We used phosphorus 31 magnetic resonance spectroscopy to assess calf muscle oxidative metabolism in subjects with molecularly defined dominant optic atrophy carrying different mutations in the OPA1 gene. In a subset of patients, we also evaluated serum lactate levels after exercise and muscle biopsy results for histology and mitochondrial DNA analysis. SETTING: University neuromuscular and neurogenetics and magnetic resonance imaging units. PATIENTS: Eighteen patients with dominant optic atrophy were enrolled from 8 unrelated families, 7 of which carried an OPA1 mutation predicted to induce haploinsufficiency and 1 with a missense mutation in exon 27. Fifteen patients had documented optic atrophy. MAIN OUTCOME MEASURES: Presence of skeletal muscle mitochondrial oxidative phosphorylation dysfunction as assessed by phosphorus 31 magnetic resonance spectroscopy, serum lactate levels, and histological and mitochondrial DNA analysis. RESULTS:Phosphorus 31 magnetic resonance spectroscopy showed reduced phosphorylation potential in the calf muscle at rest in patients with an OPA1 mutation (-24% from normal mean; P = .003) as well as a reduced maximum rate of mitochondrial adenosine triphosphate synthesis (-36%; P < .001; ranging from -28% to -49% in association with different mutations). In 4 of 10 patients (40%), the serum lactate level after exercise was elevated. Only 2 of 5 muscle biopsies, from the 2 patients with a missense mutation, showed slight myopathic changes. Low levels of mitochondrial DNA multiple deletions were found in all muscle biopsies. CONCLUSIONS: Defective oxidative phosphorylation in skeletal muscle is a subclinical feature of patients with OPA1-related dominant optic atrophy, indicating a systemic expression of the OPA1 defect, similar to that previously reported for Leber hereditary optic neuropathy due to complex I dysfunction. This defect of oxidative phosphorylation does not appear to depend on the low amounts of mitochondrial DNA multiple deletions detected in muscle biopsies.
Authors: F Caffin; A Prola; J Piquereau; M Novotova; D J David; A Garnier; D Fortin; M V Alavi; V Veksler; R Ventura-Clapier; F Joubert Journal: J Physiol Date: 2013-09-16 Impact factor: 5.182
Authors: Josie J Gray; Amelia E Zommer; Ron J Bouchard; Nathan Duval; Craig Blackstone; Daniel A Linseman Journal: Brain Res Date: 2012-12-07 Impact factor: 3.252
Authors: Leonardo Caporali; Anna Maria Ghelli; Luisa Iommarini; Alessandra Maresca; Maria Lucia Valentino; Chiara La Morgia; Rocco Liguori; Claudia Zanna; Piero Barboni; Vera De Nardo; Andrea Martinuzzi; Giovanni Rizzo; Caterina Tonon; Raffaele Lodi; Maria Antonietta Calvaruso; Martina Cappelletti; Anna Maria Porcelli; Alessandro Achilli; Maria Pala; Antonio Torroni; Valerio Carelli Journal: Biochim Biophys Acta Date: 2012-12-14