BoneKEy Reports | BoneKEy Watch
Healthy ageing twin study reveals role of genetic factors on BMD
DOI:10.1038/bonekey.2012.163
A large longitudinal study in twins has looked at how heritable factors contribute to bone mineral density (BMD) levels in middle-age to old-age. A total of 2716 female twins taking part in an ongoing 17-year follow-up as part of the Healthy Ageing Twin Study were chosen for inclusion. All were over 35 and had received two hip and lumbar spine DXA scan results at least four years apart.
A mixed-effects random-coefficients model was used to predict how the hip and spine BMD was likely to change over time from 40 to 80 years. Adjustments were made for baseline age, height, weight and hormone replacement therapy.
Genetic factors were identified as being the most important contributors to BMD values, even in women over 70. Heritable factors did not, however, correlate well with the change in BMD with age, i.e. with bone loss. Non-genetic factors were much more important in determining bone loss after the age of 65. The authors suggest that future studies studying genetic or epigenetic markers relevant to osteoporosis need to look at bone mass and bone loss as well as age to gain an accurate view.
Editor's comment: Heritability of change in BMD is generally lower than that of one-time measurement. In this study, h2 estimates decreased with age in early postmenopausal women, and there appeared to be no heritability of BMD changes after the age of 65. While genetic ('programmed') factors appear to have an important influence on bone loss in earlier life, stochastic processes (e.g. changed environment) seem to become more important in elderly women.
This work is licensed under a
Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.