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Washington University Experience | MUSCLE | Myopathies with Mitochondrial Pathology | 27A5 Muscle Bx (Case 27) EM022 - Copy

Ultrastructural examination shows myofibers with focally increased numbers of mitochondria. Further, there is occasional clustering, and notable variability in the size and shapes of mitochondria examined, including some enlarged forms and very abnormal shapes. (electron micrographs) ---- There are normal COX and SDH stains. ---- Additional NM workup showed a probable mitochondrial disorder with combined oxidative complex deficiencies. Complex I activity is zero. Complex II+III and Complex III activities are reduced. Complex II is mildly reduced. Other mitochondrial oxidative enzyme activity levels are normal. Values have been corrected for the reduced citrate synthase level. In this case the ultrastructural findings are minimal in the presence of functional mitochondrial abnormalities.

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