Abstract
Pompe's disease is characterized biochemically by a generalized deficiency of acid α-1,4-glucosidase activity. The fact that normal leukocyte activity is occasionally found in these patients has serious diagnostic implications and raises interesting questions in regard to the etiology, genetic expression, and therapy of this disease. In the patient studied, a normal level of acid α-glucosidase activity was found in the lysosomal fraction of the leukocytes, but less than 5% of normal enzyme activity and an elevated 8.7% glycogen were detected in a muscle biopsy. Cadaver heart and liver contained 7.6% and 7.9% glycogen. Less than 2% of normal acid α-glucosidase activity was measurable in these tissues.
Long-term cultured lymphocytes and fibroblasts contain 10.2% and 24.2% of normal activity respectively. These two cell cultures were compared to normal cultures with respect to enzyme-substrate affinity and isozyme patterns.
Radioisotope labeling showed the glycogen content of Pompe's fibroblasts to be twice that of normal cells. Chase experiments indicate that while all glycogen of normal cells has a half life of 4 days, only 50% of the glycogen in Pompe's fibroblasts turns over this rapidly. The remainder has a half life greater than 30 days. This stable glycogen component may be similar to the excess lysosomal glycogen found in vivo and may serve to test for corrective factors at the cellular level.
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Hieber, V., Schmickel, R. POMPE'S DISEASE WITH NORMAL LEUKOCYTE ACID α-1, 4-GLUCOSIDASE ACTIVITY: ENZYME AND GLYCOGEN IN TISSUES AND CULTURED CELLS. Pediatr Res 8, 433 (1974). https://doi.org/10.1203/00006450-197404000-00558
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DOI: https://doi.org/10.1203/00006450-197404000-00558