title: Quantification of changes in muscle from individuals with and without mitochondrial disease.
abstract: BACKGROUND
  Muscle biopsy is used in the diagnosis of mitochondrial disorders. There are limited data on the normal ranges, so interpretation of findings can be difficult.
  
  
  METHODS
  We evaluated the percentage of fibers showing mitochondrial abnormalities using Gomori trichrome staining, succinate dehydrogenase, and cytochrome oxidase histochemistry in autopsy samples taken from 45 individuals without evidence of muscle disease and biopsies from 17 patients with mitochondrial disorders.
  
  
  RESULTS
  In controls, mitochondrial abnormalities were rare before the fifth decade, and most had <0.1% abnormal fibers. The proportion of abnormal fibers increased with age and was higher in deltoid than quadriceps. Most patients with mitochondrial disorders had >0.5% abnormal fibers.
  
  
  CONCLUSIONS
  Although some patients with mitochondrial disease have very few muscle fibers that show mitochondrial abnormalities, a rate of abnormality of >0.5% fibers, in the absence of a primary muscle disease this should raise the possibility of a mitochondrial disorder.
authors: Department of Cellular and Anatomical Pathology, Derriford Hospital, Plymouth PL6 8DH, UK.
authors: Kerry
authors: K
authors: Sleigh
authors: Susan
authors: S
authors: Ball
authors: David A
authors: DA
authors: Hilton