Abstract
Summary
The genetic contribution to age-related bone loss is not well understood. We estimated that genes accounted for 25–45% of variation in 5-year change in bone mineral density in men and women. An autosome-wide linkage scan yielded no significant evidence for chromosomal regions implicated in bone loss.
Introduction
The contribution of genetics to acquisition of peak bone mass is well documented, but little is known about the influence of genes on subsequent bone loss with age. We therefore measured 5-year change in bone mineral density (BMD) in 300 Mexican Americans (>45 years of age) from the San Antonio Family Osteoporosis Study to identify genetic factors influencing bone loss.
Methods
Annualized change in BMD was calculated from measurements taken 5.5 years apart. Heritability (h2) of BMD change was estimated using variance components methods and autosome-wide linkage analysis was carried out using 460 microsatellite markers at a mean 7.6 cM interval density.
Results
Rate of BMD change was heritable at the forearm (h2 = 0.31, p = 0.021), hip (h2 = 0.44, p = 0.017), spine (h2 = 0.42, p = 0.005), but not whole body (h2 = 0.18, p = 0.123). Covariates associated with rapid bone loss (advanced age, baseline BMD, female sex, low baseline weight, postmenopausal status, and interim weight loss) accounted for 10% to 28% of trait variation. No significant evidence of linkage was observed at any skeletal site.
Conclusions
This is one of the first studies to report significant heritability of BMD change for weight-bearing and non-weight-bearing bones in an unselected population and the first linkage scan for change in BMD.
Similar content being viewed by others
References
Dennison E, Cole Z, Cooper C (2005) Diagnosis and epidemiology of osteoporosis. Curr Opin Rheumatol 17:456–461
Cummings SR, Kelsey JL, Nevitt MC et al (1985) Epidemiology of osteoporosis and osteoporotic fractures. Epidemiol Rev 7:178–208
Krall EA, Dawson-Hughes B (1993) Heritable and life-style determinants of bone mineral density. J Bone Miner Res 8:1–9
Wilkins CH, Birge SJ (2005) Prevention of osteoporotic fractures in the elderly. Am J Med 118:1190–1195
Eisman JA (1999) Genetics of osteoporosis. Endocr Rev 20:788–804
Huang QY, Kung AW (2006) Genetics of osteoporosis. Mol Genet Metab 88:295–306
Kammerer CM, Schneider JL, Cole SA et al (2003) Quantitative trait loci on chromosomes 2p, 4p, and 13q influence bone mineral density of the forearm and hip in Mexican Americans. J Bone Miner Res 18:2245–2252
Mitchell BD, Kammerer CM, Schneider JL et al (2003) Genetic and environmental determinants of bone mineral density in Mexican Americans: results from the San Antonio Family Osteoporosis Study. Bone 33:839–846
Dirschl DR, Henderson RC, Oakley WC (1997) Accelerated bone mineral loss following a hip fracture: a prospective longitudinal study. Bone 21:79–82
Engelke K, Kemmler W, Lauber D et al (2006) Exercise maintains bone density at spine and hip EFOPS: a 3-year longitudinal study in early postmenopausal women. Osteoporos Int 17:133–142
Hannan MT, Felson DT, Dawson-Hughes B et al (2000) Risk factors for longitudinal bone loss in elderly men and women: the Framingham Osteoporosis Study. J Bone Miner Res 15:710–720
Warming L, Hassager C, Christiansen C (2002) Changes in bone mineral density with age in men and women: a longitudinal study. Osteoporos Int 13:105–112
Knoke JD, Barrett-Connor E (2003) Weight loss: a determinant of hip bone loss in older men and women. The Rancho Bernardo Study. Am J Epidemiol 158:1132–1138
Sornay-Rendu E, Munoz F, Duboeuf F et al (2005) Rate of forearm bone loss is associated with an increased risk of fracture independently of bone mass in postmenopausal women: the OFELY study. J Bone Miner Res 20:1929–1935
Yang F, Shen H, Jiang H et al (2006) On genetic studies of bone loss. J Bone Miner Res 21:1676–1677
Christian JC, Yu PL, Slemenda CW et al (1989) Heritability of bone mass: a longitudinal study in aging male twins. Am J Hum Genet 44:429–433
Kelly PJ, Nguyen T, Hopper J et al (1993) Changes in axial bone density with age: a twin study. J Bone Miner Res 8:11–17
Makovey J, Nguyen TV, Naganathan V et al (2007) Genetic effects on bone loss in peri- and postmenopausal women: a longitudinal twin study. J Bone Miner Res 22:1773–1780
Hui SL, Koller DL, Foroud TM et al (2006) Heritability of changes in bone size and bone mass with age in premenopausal white sisters. J Bone Miner Res 21:1121–1125
Green P, Falls K, Crooks S (1990) Documentation for CRI-MAP, Version 2.4. In. Washington University School of Medicine, St. Louis, MO, USA
Brown LB, Streeten EA, Shapiro JR et al (2005) Genetic and environmental influences on bone mineral density in pre- and post-menopausal women. Osteoporos Int 16:1849–1856
Heath SC (1997) Markov chain Monte Carlo segregation and linkage analysis for oligogenic models. Am J Hum Genet 61:748–760
Blangero J, Williams JT, Almasy L (2000) Robust LOD scores for variance component-based linkage analysis. Genet Epidemiol 19 Suppl 1:S8–14
Almasy L, Blangero J (1998) Multipoint quantitative-trait linkage analysis in general pedigrees. Am J Hum Genet 62:1198–1211
Burger H, van Daele PL, Odding E et al (1996) Association of radiographically evident osteoarthritis with higher bone mineral density and increased bone loss with age. The Rotterdam Study. Arthritis Rheum 39:81–86
Smith JA, Vento JA, Spencer RP et al (1999) Aortic calcification contributing to bone densitometry measurement. J Clin Densitom 2:181–183
Zmuda JM, Cauley JA, Glynn NW et al (2000) Posterior-anterior and lateral dual-energy x-ray absorptiometry for the assessment of vertebral osteoporosis and bone loss among older men. J Bone Miner Res 15:1417–1424
Wilson SG, Reed PW, Bansal A et al (2003) Comparison of genome screens for two independent cohorts provides replication of suggestive linkage of bone mineral density to 3p21 and 1p36. Am J Hum Genet 72:144–155
Brown LB, Streeten EA, Shuldiner AR et al (2004) Assessment of sex-specific genetic and environmental effects on bone mineral density. Genet Epidemiol 27:153–161
Wang X, Kammerer CM, Wheeler VW et al (2007) Genetic and environmental determinants of volumetric and areal BMD in multi-generational families of African ancestry: the Tobago Family Health Study. J Bone Miner Res 22:527–536
Devoto M, Spotila LD, Stabley DL et al (2005) Univariate and bivariate variance component linkage analysis of a whole-genome scan for loci contributing to bone mineral density. Eur J Hum Genet 13:781–788
Ioannidis JP, Ng MY, Sham PC et al (2006) Meta-Analysis of Genome Wide Scans Provides Evidence for Gender and Site Specific Regulation of Bone Mass. J Bone Miner Res 22:173–183
Liu YJ, Shen H, Xiao P et al (2006) Molecular genetic studies of gene identification for osteoporosis: a 2004 update. J Bone Miner Res 21:1511–1535
Peacock M, Koller DL, Hui S et al (2004) Peak bone mineral density at the hip is linked to chromosomes 14q and 15q. Osteoporos Int 15:489–496
Streeten EA, McBride DJ, Pollin TI et al (2006) Quantitative trait loci for BMD identified by autosome-wide linkage scan to chromosomes 7q and 21q in men from the Amish Family Osteoporosis Study. J Bone Miner Res 21:1433–1442
Styrkarsdottir U, Cazier JB, Kong A et al (2003) Linkage of osteoporosis to chromosome 20p12 and association to BMP2. PLoS Biol 1:E69
Schwartz AV, Sellmeyer DE, Strotmeyer ES et al (2005) Diabetes and bone loss at the hip in older black and white adults. J Bone Miner Res 20:596–603
Seeman E (1998) Growth in bone mass and size–are racial and gender differences in bone mineral density more apparent than real? J Clin Endocrinol Metab 83:1414–1419
Cauley JA, Lui LY, Stone KL et al (2005) Longitudinal study of changes in hip bone mineral density in Caucasian and African-American women. J Am Geriatr Soc 53:183–189
Tracy JK, Meyer WA, Flores RH et al (2005) Racial differences in rate of decline in bone mass in older men: the Baltimore men’s osteoporosis study. J Bone Miner Res 20:1228–1234
Acknowledgements
We are deeply grateful for the cooperation of the families participating in the SAFOS. This work was supported by research grants R01-AR43351 and P01-HL45522 awarded by the National Institutes of Health. Support for the Frederic C. Bartter General Clinical Research Center was made available by Clinical National Institutes of Health Grant M01-RR-01346. Development of SOLAR is supported by R01-HG59490. We would also like to express our gratitude to three anonymous reviewers for their thoughtful consideration of this work.
Disclaimers
Funding:National Institutes of Health research grants R01-AR43351, P01-HL45522, and R01-HG59490; Clinical National Institutes of Health grant M01-RR-01346.
Conflicts of interest
None.
Author information
Authors and Affiliations
Corresponding author
Appendix
Appendix
DXA measurement and cross-validation
Due to an upgrade in equipment, densitometry was carried out on a pencil-beam Hologic Model 1500 at baseline examination (1997–2000) and a fan-beam Model 4500 W at follow-up examination (2002–2006). For both densitometers, areal BMD was calculated by manufacturer’s software as per current recommendations by dividing bone mineral content (g) by the projected area of the region scanned (cm2). Precision of pencil-beam DXA was 0.009 g/cm2 for spine, 0.007 g/cm2 for total hip, and 0.002 g/cm2 for the manufacturer’s spine phantom. Precision of fan-beam DXA was 0.006 g/cm2 for spine, 0.007 g/cm2 for hip, and 0.002 g/cm2 for radius. Based on the precision of our equipment, least significant change (at 95% confidence) was 3.2 mg/cm2/year for hip, 3.1 mg/cm2/year for spine, and 1.1 mg/cm2/year for forearm DXA measurements.
To address the comparability in our study of measurements taken from Hologic 1500 and 4500 W scanners, we performed cross-calibration of absorptiometry equipment used at baseline and follow-up on 10 participants. Measurements obtained from the two scanners showed near-perfect agreement (R2 values = 99.95%, 99.81%, and 99.87% for spine, total hip, and femoral neck sites, respectively; p-value <10–13 for all). Moreover, regression slopes (0.99, 0.99, and 1.01, respectively, for spine, total hip, and femoral neck; p-value < 10–13 for all) and paired T-tests (p > 0.1, for all) revealed no evidence of systematic or mean differences between absorptiometers. This evaluation of equipment indicates that measurements from Hologic 1500 and 4500 W scanners used in this study are comparable, and that 5-year change in BMD can be adequately calculated. Cross-calibration was not performed for forearm BMD, although we expect that measurements at this site are equally comparable.
Robustness of methods to measurement error
Though we found no evidence to suggest that systematic differences exist in the measurements between scanners, we have nonetheless employed statistical methods that are robust to potential differences. If present, such bias (e.g., systematic measurement error) would decrease our power to detect covariate effects and attenuate our estimate of heritability and linkage, but should not otherwise affect our results. That is, machine differences leading to biased estimates of BMD change could prevent us from assessing environmental and genetic factors affecting BMD change, but would not produce false positive results or lead to overestimation of effects sizes. Our findings, therefore, are conservative. Furthermore, we recognize that deviations from absolute agreement between machines would not adversely affect the genetic analyses as long as the relative BMD between individuals as measured by each scanner is accurate (i.e., variances are comparable). In other words, as long as BMD measured for an individual at baseline is accurate relative to the baseline measurements of the rest of the study sample, and the same holds for measurements at follow-up, the estimation of heritability will be unaffected by inter-machine differences. This is because the genetic modeling used to assess heritability decomposes the trait variance into genetic and environmental components irrespective of the trait mean.
To demonstrate this point, we removed the possibility of any inter-machine effects by first standardizing (mean=0, SD = 1) the BMD measurements in our sample separately at baseline and follow-up, and then analyzing yearly change in standardized values. This process retains the information of individuals’ measurements relative to the sample, but not of the absolute magnitude of measurements. In doing so, potential unknown machine differences that could invalidate direct inter-machine comparisons are avoided. Results (not shown) of change in standardized BMD are very similar to the absolute change reported herein. Likewise, results (not shown) of percent change in BMD were also similar.
Attenuation of heritability due to measurement error
The precision of DXA, which is excellent when looking at cross-sectional BMD measurements, is poor when looking at change over time, leading to considerable uncertainty of actual rates of change. Therefore, rates of change assessed in this study are notably crude, with a large percentage of observations being less than our measurement uncertainty (i.e., no measurable change). Since noise constitutes a substantial portion of the variation in observed rates of change, our results represent a considerable underestimation of the heritability of observed BMD change compared to that of true change (free of such measurement error) [19]. Noise due to our crude assessment of BMD change effectively drowns the heritability signal, and diminishes our ability to detect linkage.
Rights and permissions
About this article
Cite this article
Shaffer, J.R., Kammerer, C.M., Bruder, J.M. et al. Genetic influences on bone loss in the San Antonio Family Osteoporosis study. Osteoporos Int 19, 1759–1767 (2008). https://doi.org/10.1007/s00198-008-0616-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00198-008-0616-0