Recombinant osteoprotegerin for juvenile Paget's disease.

Juvenile Paget's disease, a genetic bone disease characterized by accelerated bone turnover, results from inactivating mutations in the gene encoding osteoprotegerin--a key regulator of osteoclastogenesis. The effects of recombinant osteoprotegerin were investigated in two adult siblings with juvenile Paget's disease. Bone resorption (assessed by N-telopeptide excretion) was suppressed by once-weekly subcutaneous doses of 0.3 to 0.4 mg per kilogram of body weight. After 15 months of treatment, radial bone mass increased in one patient by 9 percent and in the other by 30 percent, skeletal bisphosphonate retention decreased by 37 percent and 55 percent, respectively, and there was radiographic improvement. Apart from mild hypocalcemia and hypophosphatemia, no apparent adverse events occurred.