Glutamate dehydrogenase in olivopontocerebellar atrophies: leukocytes, fibroblasts, and muscle mitochondria.

Glutamate dehydrogenase (GDH) activity was 68% of control values in leukocyte homogenates of 11 patients with dominant olivopontocerebellar atrophies (OPCA) and 46% in muscle mitochondria of 4 patients with dominant OPCA. In three patients with recessive OPCA and in one sporadic patient, muscle GDH was lower than in controls. However, muscle GDH activity was normal in one of two dominant patients in the same family and decreased in the other, and patients' activities overlapped with lower control values. Plasma glutamate levels were significantly higher in dominant patients than in controls after glutamate challenge. GDH activity may be partially altered at the mitochondrial level in a subgroup of OPCA patients.