Reduced activity of serum beta-glucuronidase in Marfan syndrome.

Reduced activity of serum beta-glucuronidase (EC 3.2.1.31) was found in three patients with Marfan syndrome, two of whom were siblings. The serum beta-glucuronidase levels in the patients ranged from 294 to 439 micrograms (360.7 +/- 73.2, mean +/- SD) of the released P-nitrophenol/100 ml of serum/hour, whereas those of 7 healthy subjects ranged from 564 to 1445 micrograms (836.4 +/- 287.3). This difference was statistically significant (p less than 0.01). Plasma glycosaminoglycan levels in the patients were lower than those in the healthy subjects, owing mainly to the differences in plasma high-sulfated glycosaminoglycan. The correlation coefficients of serum beta-glucuronidase activity with high-sulfated and total plasma glycosaminoglycans were 0.794 and 0.809, respectively (p less than 0.01 and p less than 0.005, respectively). The results suggest that the decreased plasma high-sulfated glycosaminoglycan levels in Marfan syndrome are due to the reduction of serum beta-glucuronidase, which leads to the decreased degradation of macromolecules and, subsequently, the accumulation of the glycosaminoglycans in the tissues.