Vitamin D receptor gene variants: implications for therapy.

Osteoporosis is a major health problem in virtually all societies where its incidence and impact have been studied in terms of cost, morbidity, mortality and quality of life. The major determinant of fracture risk is bone density and, presumably, bone strength. A large number of lifestyle influences and medical interventions modify bone density, but the variation and slowness of change in response to any intervention necessitates long-term follow up. The definition of genetic factors in the determination of bone mass, and possibly in the changes in bone density, over time offer important insights into the mechanisms of response to treatment. Most importantly, if genetic factors can determine response to therapy, the understanding of such factors could influence selection of optimum therapy.