Genetic aspects of osteoporosis.

Genetically determined factors strongly contribute to bone mass in healthy individuals, although their molecular nature has long remained mysterious. Structural abnormalities in type I collagen may explain some cases of severe osteoporosis. The results of recent studies also indicate that bone mass in healthy populations may be influenced by genetically controlled variations in the regulation of type I collagen synthesis and degradation, via genetic factors that appear to be different from those presumably regulating bone formation. But the major breakthrough of this past year has been the demonstration that variations in the gene encoding the vitamin D receptor may account for a substantial part of bone mass variance in healthy pre- and postmenopausal populations. Although this assertion is at present the subject of an animated controversy, it has widely opened the way to possible intervention and to the search for other regulators of bone turnover putatively underlying the genetic effect on bone mass.