Increased amounts of hyaluronic acid accumulate in fibroblasts cultured from patients with Marfan's disease, an autosomal dominant disorder. In the recessive Hurler's disease, the storage of glycosaminoglycan (GAG) is due to impaired degradation. This study examines the kinetics of GAG accumulation in Marfan's disease in order to determine whether the mechanism of accumulation differs from that in Hurler's disease. Marfan derived fibroblasts incorporated [14C]acetate or [14C]glucosamine into GAG to a level 4-6 times greater than control fibroblasts. Sugar analyses, electrophoretic mobility, and enzyme susceptibility studies showed that the isolated material was hyaluronic acid. There were no differences in activity of a variety of glycosidases between Marfan and control fibroblasts, nor were there differences in the ability to degrade prelabeled hyaluronate by cell free extracts. Finally, chase experiments showed parallel rates of loss of labeled GAG from control fibroblasts and fibroblasts from Marfan patients. It appears that hyaluronic acid was accumulating in greater amounts in the fibroblasts from patients with Marfan's disease because of a greater rate of synthesis as opposed to a decreased rate of breakdown.
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