Osteoporosis is a common disease that affects 1 in 3 women. Family and twin studies have demonstrated that there is a strong genetic component to this condition. Potential candidate genes examined for their regulatory effect on bone mass include those for collagen type I, estrogen and vitamin D receptors, and various cytokines and growth factors. To date, most work has focused on the vitamin D receptor (VDR) gene, and experience with this locus will probably act as a model for many future studies.

There is increasing evidence, from population studies that have examined the relationship between VDR genotype and bone mineral density, of genetic heterogeneity and gene-environment interactions. Response to therapeutic agents may also be affected by an individual’s underlying genotype, partly explaining the range of responses that are commonly observed in clinical practice. Knowledge of a person’s genotype could, therefore, allow current therapies to be targeted to those most likely to benefit, with a possible reduction in adverse effects. Large-scale genomic studies of osteoporosis may also identify novel genes, and this may lead to both a better understanding of disease pathophysiology and to the discovery of potential targets for drug development.