Résumé :
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We report on a nine-year girl who was referred for early fatigue and exercise-induced pain. Those symptoms as well as cramps had developed during early childhood. CK were elevated by one and a half. On clinical examination, a mild pelvic girdle weakness was discovered and muscles strength was graduated 4. Skeletal Muscles were normal in size and the tendon reflexes were present. Screening for other inborn-errors of energy metabolism was negative. Electromyography was normal. Exercise test failed to produce ammonia. Muscle biopsy was performed on vastus medialis. No abnormal fiber pattern was observed. However, complete deficit of activity with AMP deaminase was detected by enzymohistochemistry on the muscle biopsy. The deficiency was confirmed by molecular analysis. A homozygous C34T mutation in the AMPD1 gene was present in the patient and both parents were heterozygous. As this young girl was complaining about her every day life and about school difficulties administration of D-Ribose was tested. The benefit of this treatment was obvious as exercise-induced symptoms decreased. These improvements allowed the young patient to start again a regular practice of sports. Control exercise test under D-Ribose treatment did not find any ammonia production but CK did not rise. As a conclusion, AMP deaminase deficiency could be suspected by a exercise test. Symptoms could be strongly improved by D-Ribose intake particularly in children. These positive results could suggest D-Ribose administration, at least as a test, every time exercise-related symptoms are present.
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