Friedreich ataxia: III. Mitochondrial malic enzyme deficiency

David A. Stumpf*, Janice K. Parks, Luis A. Eguren, Richard Haas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Polarographic assays of oxidative phosphorylation in muscle mitochondria indicated abnormal pyruvate-malate metabolism in Friedreich ataxia (FA). Pursuing this clue, more specific assays were performed. Mitochondrial malic enzyme (MEm; malate: NADP oxidoreductase) specific activity was 10% of controls in fibroblasts from eight FA patients (p < 0.0001). Cytosolic malic enzyme was modestly increased in FA fibroblasts. Mitochondrial and cytosolic malate dehydrogenase and aspartate aminotransferase, and inalate transport on the dicarboxylate and a-ketoglutarate carriers were normal in fibroblasts or leukocytes. MEm activity is normally highest in the nervous system and heart and is important in regulating carbohydrate metabolism. MEm deficiency could cause FA; further studies are required to substantiate this hypothesis.

Original languageEnglish (US)
Pages (from-to)221-227
Number of pages7
Issue number3
StatePublished - Mar 1982

ASJC Scopus subject areas

  • Clinical Neurology


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