In postmenopausal women with osteoporosis or decreased BMD, longer treatment duration (1 to 5 years), increasing age, lower body weight, increasing time since menopause, lower baseline T score of lumbar spine, lower baseline serum levels of 25-OH vitamin D, and higher baseline serum levels of CTX and BSAP predicted better efficacy of ibandronate in improving BMD of the lumbar spine (Table 2). The gene discussed is CYP27A1; the disease is osteoporosis.