Effectiveness of alendronate treatment in postmenopausal women with osteoporosis: relationship with BsmI vitamin D receptor genotypes.

OBJECTIVE: To assess whether there is a relationship between the effectiveness of alendronate treatment in postmenopausal women with osteoporosis and BsmI vitamin D receptor (VDR) genotypes.
DESIGN: Prospective baseline-controlled clinical trial. PATIENTS: Sixty-eight Italian osteoporotic women were enrolled and treated with alendronate at a dose of 10 mg/day for 12 months. MEASUREMENTS: At entry and after treatment, lumbar bone mineral density (BMD) and serum osteocalcin (OC) and urinary deoxypyridinoline/creatinine ratio (DPD-Cr) levels were evaluated. DNA was extracted from blood and analysed for the BsmI polymorphism of the VDR gene.
RESULTS: The mean percentage (% +/- SD) change from baseline in lumbar BMD was significantly higher (P < 0.01) in bb than in BB BsmI VDR genotypes (7.92 +/- 4.31 vs. 3.40 +/- 1.81). No significant difference in lumbar BMD was observed in Bb VDR patients (6.01 +/- 3.89) in comparison with other groups. The mean percentage of change in serum OC and urinary DPD-Cr levels was significantly (P < 0.01) lower in individuals with bb than in those with BB BsmI VDR genotypes (-14.34 +/- 2.87 vs.-10.39 +/- 1.43 and -9.61 +/- 5.56 vs.-4.61 +/- 2.31). No significant difference in serum OC and urinary DPD-Cr levels was observed in Bb VDR patients (-12.31 +/- 2.11 and -6.52 +/- 2.65) in comparison with other groups.
CONCLUSION: The different BsmI vitamin D receptor genotypes modify the pharmacological response to alendronate treatment in postmenopausal women with osteoporosis.