title: Exercise intolerance, muscle pain and lactic acidaemia associated with a 7497G>A mutation in the tRNASer(UCN) gene.
abstract: A 13-year-old girl with non-familial exercise intolerance, muscle pain and lactic acidaemia underwent a muscle biopsy for suspected mitochondrial disease. Muscle morphology showed 25% ragged-red fibres and 80% COX-negative staining. Enzymatic activities of mitochondrially co-encoded respiratory chain enzymes (complexes I, III, and IV) were decreased in muscle but normal in cultured skin fibroblasts. mtDNA analysis revealed the presence of the 7497G>A mutation in the tRNASer(UCN) gene, homoplasmic in skeletal muscle and 90% in leukocytes. Analysis of the mother's mtDNA showed 10% heteroplasmy in blood. It may be concluded that the 7497G>A mutation is associated with a muscle-only disease presentation for which high levels of mutated mtDNA are required. Exercise intolerance and muscle pain in otherwise normal children warrants further mitochondrial evaluation.
authors: Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, University Medical Center Nijmegen, The Netherlands.
authors: O
authors: O
authors: Grafakou
authors: F A
authors: FA
authors: Hol
authors: K
authors: K
authors: Otfried Schwab
authors: M H
authors: MH
authors: Siers
authors: H
authors: H
authors: ter Laak
authors: F
authors: F
authors: Trijbels
authors: R
authors: R
authors: Ensenauer
authors: C
authors: C
authors: Boelen
authors: J
authors: J
authors: Smeitink
mesh_terms: D000140:Acidosis, Lactic / Q000150:complications / Q000235:genetics*; D000293:Adolescent; D001921:Brain / Q000473:pathology; D004272:DNA, Mitochondrial / Q000235:genetics; D004562:Electrocardiography; D004569:Electroencephalography; D004576:Electromyography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D017079:Exercise Tolerance / Q000235:genetics*; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D008279:Magnetic Resonance Imaging; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology; D009135:Muscular Diseases / Q000235:genetics* / Q000473:pathology; D010084:Oxidation-Reduction; D010146:Pain / Q000150:complications / Q000235:genetics*; D012362:RNA, Transfer, Ser / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D004272:DNA, Mitochondrial; D012362:RNA, Transfer, Ser