Genetics of osteoporosis.

Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass and an increased risk of fragility fractures. Twin and family studies have shown that the heritability of bone mineral density and other determinants of fracture risk, such as ultrasound properties of bone, skeletal geometry, and bone turnover, is high, although heritability of fracture is modest. Many different genetic variants contribute to the regulation of these phenotypes. Most are common variants of small effect size, but there is evidence that rare variants of large effect size also contribute in some individuals. Many of the genes that regulate susceptibility to osteoporosis have been identified through studies of rare bone diseases, but genome-wide association studies have also been successful in identifying genes that predispose to osteoporosis. Although there has been extensive progress in this area over the past 10 years, most of the genetic variants that regulate susceptibility to osteoporosis remain to be discovered.