Friedreich's ataxia associated with mitochondrial myopathy: clinicopathologic report.
A 13-year-old boy with clinical and electrophysiologic findings of Friedreich's ataxia developed unusually prominent myopathy. Skeletal muscle biopsy showed mitochondrial proliferation and structural abnormalities. No mutation was found in skeletal muscle mitochondrial DNA to explain this finding. Molecular genetic and pathologic studies confirmed a diagnosis of Friedreich's ataxia in the proband and affected relatives. Although the Friedreich's ataxia phenotype results from decreased expression of a mitochondrially targeted protein, frataxin, mitochondrial myopathy has not been described as a feature of the disease. The association between the frataxin gene mutation and mitochondrial myopathy in this case suggests that severe or cumulative insults to mitochondrial function may produce myopathic changes in some cases of Friedreich's ataxia. The patient also responded clinically to carnitine supplementation, suggesting a potential palliative therapy for the disease.
Gallagher
Catherine L
CL
Department of Neurology, University of Wisconsin, Madison, USA. gallagher@neurology.wisc.edu
Waclawik
Andrew J
AJ
Beinlich
Brad R
BR
Harding
Cary O
CO
Pauli
Richard M
RM
Poirer
Josée
J
Pandolfo
Massimo
M
Salamat
M Shahriar
MS
D000293:Adolescent; D001344:Autopsy; D001706:Biopsy; D002331:Carnitine / Q000627:therapeutic use; D004272:DNA, Mitochondrial / Q000032:analysis; D018450:Disease Progression; D005621:Friedreich Ataxia / Q000150:complications* / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D006801:Humans; D033862:Iron-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D008931:Mitochondria, Muscle / Q000235:genetics / Q000473:pathology*; D017240:Mitochondrial Myopathies / Q000235:genetics*; D018482:Muscle, Skeletal / Q000473:pathology*; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D000096923:Frataxin
D002331:Carnitine; D004272:DNA, Mitochondrial; D033862:Iron-Binding Proteins; D000096923:Frataxin