Pamidronate (PAM) infusion is the standard treatment in children with osteogenesis imperfecta (OI). Zoledronic acid (ZOL) is a bisphosphonate with higher potency and faster intravenous infusion, but its effi cacy and safety has not been established for OI patients. We report an open-label, prospective, and randomized clinical analysis to study the safety and effi cacy of ZOL compared with PAM in 23 children with OI. They were selected to receive PAM (PAM group), 1 mg/kg/day, over 2 days or ZOL (ZOL group), 0.025 -0.05 mg/kg/day, over 2 days every 3 -4 months according to their ages, during a 1-year follow-up. They were observed for clinical and biochemical parameters, side effects, bone mineral density (BMD), and fracture rate. After treatment, the PAM and ZOL groups average lumbar spine (LS) BMD increased by 51.8 % (p = 0.053) and 67.6 % (p = 0.003), respectively. Parallel improvement was seen in LS Z-score in the PAM and ZOL groups, with scores of -5.3 to -3.8 (p = 0.032) and -4.8 to -2.3 (p = 0.007), respectively. LS Z-score for the ZOL group at the end of treatment was higher compared with the PAM group but only a borderline signifi cance (p = 0.053). The total alkaline phosphatase (AP) in the ZOL group significantly decreased from baseline at third and fourth infusion (p = 0.032). Mild side effects were similar in both groups, but no severe clinical symptoms were reported. In conclusion, the present study shows that the use of ZOL in the dosage and period studied was safe and effi cient to promote a clinical and densitometric improvement, similarly to PAM. Further studies are needed to establish optimal dosing and long-term safety.

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The low-density lipoprotein receptor-related protein (Lrp)-5 regulates osteoblast proliferation and bone formation through its expression in duodenum by modifying the gut serotonin-bone endocrine axis. However, its direct role, if any, in osteoblast progenitor cells has not been studied thus far. Here, we show that mice with a Dermo1-Cre-mediated disruption of Lrp5 in osteoblast progenitor cells have normal embryonic skeletogenesis and normal skeletal growth and development postnatally. Histomorphometric analysis of 3-month-old adult mice revealed normal osteoblast numbers, bone formation rate, and bone mass in Lrp5(Dermo)(-/-) mice. In addition, analysis of two osteoporosis pseudoglioma (OPPG) patients revealed a three- to fivefold increase in their serum serotonin levels compared to age-matched controls. These results rule out a direct function of Lrp5 in osteoblast progenitor cells and add further support to the notion that dysregulation of serotonin synthesis is involved in bone mass abnormalities observed in OPPG patients.

Osteoporosis Pseudoglioma (OPPG) is characterized by severe juvenile-onset osteoporosis and ocular abnormalities. It is caused by one of several inactivating mutations in LRP5, a gene importantly involved in bone formation. The objective of this study was to evaluate the efficacy of teriparatide in a young man with OPPG. The subject of this case report is a 19-year-old man with congenital blindness and low trauma fractures because of OPPG. A 2-year course of teriparatide, 20 mg/day, was initiated after a 6-year course of intravenous pamidronate infusions, the latter 3 years of which had minimal effects on bone mineral density (BMD). Measurements in serum were made of C-terminal telopeptide of type I collagen (CTX), N-terminal propeptide of type I collagen (P1NP), total and ionized calcium, phosphate, uric acid, complete blood count, and renal and liver function tests. Urinary calcium/creatinine ratio was determined. BMD was measured by DXA yearly. BMD increased by 9.7% in lumbar spine and 10.2% in right femur hip. CTX rose early, peaking in month 3, followed by an increase in P1NP, peaking in month 9. Both indices returned to baseline by month 24. The increase in CTX followed by P1NP is an unusual time course when teriparatide is used to treat osteoporosis but may be typical of low bone turnover states. There were no adverse events. In a patient with OPPG, teriparatide markedly increased BMD in the lumbar spine and femur hip. ß

The affected brothers carry a missense mutation in the third codon of exon 8 (AAT-->ATT) that led to the exchange of an asparagine for an isoleucine (N531I). Both parents were found to be heterozygous for this mutation. The intravenous pamidronate therapy was safe for up to 3 years of use. Moreover, increased BMD and decreased fracture rate were observed in our patients with OPPG.