Normal fibroblast mitochondrial malic enzyme activity in Friedreich's ataxia.

Mitochondrial and cytoplasmic malic isoenzymes were assayed fluorometrically in digitonin-fractionated fibroblasts from three patients with Friedreich's ataxia (FA). Normal activity was found, failing to verify an earlier report of reduced fibroblast mitochondrial malic enzyme activity in FA. The previously reported disturbance in fibroblast mitochondrial malic enzyme may be an epiphenomenon in patients with the FA phenotype. Further studies are necessary to define the primary genetic defect in this inherited disorder.