Article

Muscle phosphofructokinase deficiency, the seventh member of the
glycogen storage diseases family, is also called Tarui's disease (GSD VII).
METHODS: We studied two patients in two unrelated families with Tarui's disease,
analyzing clinical features, CK level, EMG, muscle biopsy findings and molecular
genetics features. Metabolic muscle explorations (forearm ischemic exercise test
[FIET]; bicycle ergometer exercise test [EE]; 31P-nuclear magnetic resonance
spectroscopy of calf muscle [31P-NMR-S]) are performed as appropriate. RESULTS:
Two patients, a 47-year-old man and a 38-year-old woman, complained of
exercise-induced fatigue since childhood. The neurological examination was normal
or showed light weakness. Laboratory studies showed increased CPK, serum uric
acid and reticulocyte count without anemia. There was no increase in the blood
lactate level during the FIET or the EE although there was a light increase in
the respiratory exchange ratio during the EE. 31P-NMR-S revealed no intracellular
acidification or accumulated intermediates such as phosphorylated monoesters
(PME) known to be pathognomic for GSD VII. Two new mutations were identified.
DISCUSSION: FIET and EE were non-contributive to diagnosis, but 31P-NMR provided
a characteristic spectra of Tarui's disease, in agreement with
phosphofructokinase activity level in erythrocytes. Muscle biopsy does not always
provide useful information for diagnosis. In these two cases, genetic studies
failed to establish a genotype-phenotype correlation. CONCLUSION: The search for
phosphofructokinase deficiency should be continued throughout life in adults
experiencing fatigability or weakness because of the severe disability for daily
life activities caused by the late onset form.
CI - Copyright (c) 2013 Elsevier Masson SAS. All rights reserved.

Langue : FRANCAIS