help button home button Endocrine Society JCEM
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Journal of Clinical Endocrinology & Metabolism , doi:10.1210/jc.2004-1618
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Reprints, Permissions and Rights
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Havill, L. M.
Right arrow Articles by Rogers, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Havill, L. M.
Right arrow Articles by Rogers, J.
Related Collections
Right arrow Calcium and Bone Metabolism
The Journal of Clinical Endocrinology & Metabolism Vol. 90, No. 6 3638-3645
Copyright © 2005 by The Endocrine Society

A Quantitative Trait Locus for Normal Variation in Forearm Bone Mineral Density in Pedigreed Baboons Maps to the Ortholog of Human Chromosome 11q

L. M. Havill, M. C. Mahaney, L. A. Cox, P. A. Morin, G. Joslyn and J. Rogers

Department of Genetics (L.M.H., M.C.M., L.A.C., J.R.) and Southwest National Primate Research Center (M.C.M., J.R.), Southwest Foundation for Biomedical Research, San Antonio, Texas 78245-0549; Southwest Fisheries Science Center (P.A.M.), La Jolla, California 92037; and Ernest Gallo Clinic and Research Center (G.J.), Emeryville, California 94608

Address all correspondence and requests for reprints to: Dr. Lorena M. Havill, Department of Genetics, Southwest Foundation for Biomedical Research, P.O. Box 760549, San Antonio, Texas 78245-0549. E-mail: lhavill{at}darwin.sfbr.org.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Baboons share many anatomical, physiological, and developmental characteristics with humans that make them excellent models for human bone maintenance and turnover. We conducted statistical genetic analyses, including a whole-genome linkage screen, of dual-energy x-ray absorptiometry-acquired measures of areal bone mineral density (aBMD), currently the most reliable single predictor of susceptibility to osteoporotic fracture in humans, from three forearm sites on the radius and ulna of 667 pedigreed baboons. We used a maximum likelihood-based variance decomposition approach to detect and quantify the effects of genes on normal variation in aBMD in the forearm of these baboons and to localize these effects to chromosomal regions. We estimated significant heritability for aBMD at all three sites and found evidence for a quantitative trait locus (QTL) contributing significantly to the genetic effects on this trait in a region of the baboon genome homologous to human chromosome 11q12-13. This first reported genome-wide linkage screen in a nonhuman primate for QTLs affecting forearm aBMD provides important cross-species replication of a QTL found in humans. The concordance of our results in a nonhuman primate with those reported for humans provides strong evidence that a gene (or genes) in this region affects normal variation in BMD.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
AREAL BONE MINERAL density (aBMD) currently serves as the most reliable single predictor of susceptibility to osteoporotic fracture (1, 2, 3), accounting for 60–70% of bone strength (4), and, depending on skeletal site, 10–44% of fractures in women over the age of 65 (5). This measure of skeletal mass is most commonly obtained using dual-energy x-ray absorptiometry (DXA), which provides an estimate of the amount of bone mineral (grams per centimeter squared) in a region of interest. Fracture risk is closely tied to aBMD such that each SD decrease in aBMD results, approximately, in its doubling (2, 6).

Although environmental factors (e.g. age, sex, diet, and exercise) are important contributors to individual variation in BMD, statistical genetic analyses in humans and nonhuman animal models clearly indicate that genes also play a substantial role (7, 8), accounting for 40–90% of BMD variance (9). Studies provide increasing evidence that gene effects vary by skeletal site (9, 10) and that multiple genes are involved (7, 8).

Several whole-genome linkage screens in humans have resulted in significant evidence for quantitative trait loci (QTLs) affecting BMD (8), including one on chromosome 11q12-13 that has received considerable attention. This region harbors the gene for low-density lipoprotein receptor-related protein 5 (LRP5), mutations of which are responsible for an autosomal dominant high bone mass phenotype (11, 12) and an autosomal recessive low bone mass phenotype in the case of osteoporosis-pseudoglioma syndrome (13). Two other Mendelian disorders, autosomal recessive osteopetrosis (14) and autosomal dominant osteopetrosis (15), also map to this region.

Equivocal, but mounting, evidence indicates that the 11q12-13 region may also harbor a gene or genes that affect normal variation in BMD in the general population (16, 17, 18, 19). This effect may be due to LRP5 polymorphisms (20) or to other genes in the region or both. Further research is warranted to elucidate the relationship between 11q12-13 and normal variation in BMD.

Animal models can be used to facilitate and expedite the search for genes influencing normal variation in osteoporosis risk factors. Indeed, much of the current knowledge of the genetics of BMD and bone turnover stems from animal models such as mice, which, relative to humans, allow for enhanced experimental manipulation and environmental control. However, extrapolation of results concerning genetic influences from mice to humans can be problematic because of the phylogenetic distance between the species and the consequent differences in skeletal maintenance and repair (21).

In contrast, the baboon, a nonhuman primate of the taxonomic family Cercopithecidae (Old World monkeys), shares physiological and developmental characteristics that make it particularly well-suited to studies of skeletal maintenance and turnover. This animal shares with humans a relatively long lifespan, bone loss with advancing age (22, 23, 24), and physiological and endocrine correlates of reproductive biology and senescence, including menopause (25, 26). More extensive characterization of the baboon model, including normal variation and age changes in aBMD in the baboon, can be found in Havill et al. (24). The similarities between baboons and humans inspire confidence that study results will be substantively relevant to humans. In addition, when QTLs are identified in the baboon, the existence of a genetic linkage map of the baboon genome consisting primarily of human microsatellite markers allows us to easily identify the corresponding chromosomal region in humans (27).

We conducted the study presented here to characterize the impact of genetic variation on normal phenotypic variation in forearm aBMD using the baboon. The specific aims of this study were to detect and quantify the effects of genes on variation in aBMD in the baboon forearm and to localize chromosomal regions that harbor loci that contribute to genetic effects. Our results reveal a QTL in a region corresponding to human 11q12-13 that affects normal variation in this baboon population. The existence of QTLs in the same location across these two primate species indicates that there is a gene (or genes) in this region that is important to normal variation in BMD in both human and nonhuman primates, thereby attesting to the importance of this region to primate skeletal biology and, ultimately, to osteoporosis risk in humans.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
We obtained data from animals ranging in age from 5.38–30.01 yr (developmentally equivalent to 16–90 yr in humans). The sample (460 females, 207 males) consisted of olive baboons (Papio hamadryas anubis), yellow baboons (Papio hamadryas cynocephalus), and their hybrids. All animals from which data were obtained are part of the much larger (n = 3700) breeding colony at the Southwest Foundation for Biomedical Research/Southwest National Primate Research Center. The colony was established during the late 1950s and early 1960s with wild-caught baboons from Kenya to facilitate the development of the baboon as a model for humans in biomedical research (28). All animals are housed out of doors in social group cages and maintained on commercial monkey chow to which they have ad libitum access. Animal care personnel and staff veterinarians provide daily maintenance and health care to all animals in accordance with the Guide for the Care and Use of Laboratory Animals (29). All procedures related to their treatment during the conduct of this study were approved by the Institutional Animal Care and Use Committee in accordance with the established guidelines.

After sedation by means of im ketamine followed by iv rompun, atropine, acepromazine, and ketamine to effect relaxation, aBMD (grams per centimeter squared) was assessed at six different skeletal sites via DXA (Lunar DPX +6529, Lunar Corp., Madison, WI). All DXA measurements were obtained using the manufacturer’s software for adults, version 3.65. Animals were scanned in a standard supine position. The scan width varied for each animal. We used Auto Width (Intelligent Scan Mode) to automatically narrow the path of the scan after locating bone masses. Speed was set manually depending on the thickness of the animal. Medium Mode was used for most animals, but Slow Mode was used for larger ones (>26-cm chest thickness). Both modes involve a scan interval of 1.2 x 1.2 mm. Three forearm sites were measured: ultradistal radius, diaphyseal radius at a point 33% proximal to the styloid process (radius 1/3), and diaphyseal ulna at a point 33% proximal to the styloid process (ulna 1/3). Five percent of the monkeys were scanned twice. The resulting coefficients of variation for ultradistal radius, radius 1/3, and ulna 1/3 were 2.3, 2.5, and 2.5%, respectively.

Data on additional variables possibly related to aBMD were also collected for each animal at the time of DXA. These variables include body weight, height (crown-rump length), and spinal osteophytosis score [related to development of spinal arthritis and diffuse idiopathic spinal hyperostosis in these animals assessed subjectively from visual inspection of radiographs and assigned a score on a four-point ordinal scale (0 = no osteophytosis, 3 = most severe osteophytosis)].

Baboon genotyping

Microsatellite markers were amplified from baboon genomic DNA by PCR. The forward primer for each microsatellite carried a fluorescent label. Amplification reactions included 2 U TaKaRa (Shiga, Japan) Taq Polymerase, 1x TaKaRa buffer, 0.33 mM dNTP mix, 1 µM forward and reverse primers, and 50 ng baboon genomic DNA. MgCl2 concentrations were optimized for each primer pair. PCR was performed with an initial denaturing step of 5 min at 94 C followed by 35 cycles of 40-sec denaturation at 94 C, 30-sec annealing, and 30-sec extension at 72 C followed by a final 5-min extension at 72 C. Annealing temperatures were optimized for each primer pair. Genotypes of baboons were determined through gel electrophoresis of the fluorescently labeled PCR products in ABI 377 automated sequencers with Gene Scan software (PerkinElmer Life and Analytical Sciences, Boston, MA) and analyzed using Genotyper software (PerkinElmer Life and Analytical Sciences). Detailed information about marker properties has been published elsewhere (27) and can be found at http://www.snprc.org/baboon/genome/index.html.

Baboon whole-genome linkage map

Genotype data from many of the same animals for whom aBMD data were obtained for this study were used to develop a first generation genetic linkage map of the baboon genome (27). Genotype data for 325 human microsatellite loci [short tandem repeats (STRs)], and six novel baboon microsatellites were used in marker-to-marker linkage analyses, facilitated by the expert system program Multimap (30, 31), which implements routines of the computer program CRIMAP (30), to produce a meiotic recombination map covering all 20 baboon autosomes. The average maker density is 7.2 cM. The most recent version of this map, used for multipoint interval mapping of aBMD QTLs in this study, contains 275 of these STRs that have been placed in unique positions at 1000:1 odds and eight more that have been placed in unique positions on the map at 100:1 odds.

Direct comparison among homologous (orthologous) loci reveals large regions of synteny in which the human marker order is conserved [seven autosomes with no major rearrangement, 15 with one or more rearrangements; please see Rogers et al. (27) for further details]. Given the degree of similarity, we have chosen to refer to baboon chromosomes by the number usually assigned their human homolog throughout the manuscript (with the baboon chromosome number in parentheses) to facilitate comprehension of our results and their comparison with the human situation. For example, chromosome 6 (Pha 4) designates the syntenic grouping of microsatellite marker loci that map to human chromosome 6, a syntenic grouping that comprises the loci on chromosome 4 in the baboon (Papio hamadryas; Pha). Using similar logic, chromosome 7_21 (Pha 3) designates a baboon chromosome that represents (relative to the human condition) a fusion of what are two different syntenic groups in humans, i.e. chromosomes 7 and 21.

Baboon pedigree

The baboons are assigned to 11 extended pedigrees that include the following relative pairs: 412 parent-offspring, 381 siblings, 32 grandparent-grandchild, 72 avuncular, 5951 half-siblings, 1212 half-avuncular, 4 first cousins, 179 half-first cousins, 40 half-first cousins once removed, 2 half-siblings and first cousins, 54 half-siblings and half-first cousins, 13 half-siblings and half-avuncular, and six double half-avuncular. Figure 1Go shows one of the smaller baboon pedigrees to illustrate the general complexity.



View larger version (31K):
[in this window]
[in a new window]
  		FIG. 1. Representative baboon pedigree.

 
Multipoint linkage analyses

We used a variance decomposition approach implemented in SOLAR (Sequential Oligogenic Linkage Analysis Routines) (32) to test for evidence of linkage between QTLs for aBMD and the 283 autosomal STR loci. This method, described in detail elsewhere (32), entails specification of the genetic covariance between arbitrary relatives as a function of the identity-by-descent (IBD) relationships at a given marker locus. The covariance matrix for a pedigree is modeled as the sum of the additive genetic covariance attributable to the QTL, the additive genetic covariance due to the effects of loci other than the QTL, and the variance due to unmeasured environmental factors.

We estimated marker locus-specific IBD probabilities for the pedigrees using a pair-wise maximum likelihood-based procedure (32). To permit multipoint analysis for QTL mapping, we employed an extension to the method of Fulker et al. (33) to estimate IBD probabilities at 1-centimorgan (cM) intervals along each chromosome. An LOD score evaluation was performed every centimorgan along each chromosome.

We tested the hypothesis of linkage by comparing the likelihood of a restricted model in which variance due to the QTL was constrained to zero (no linkage) with that of a model in which it was estimated. The LOD score of classical linkage analysis was obtained as the quotient of the difference between the 2 ln likelihoods divided by ln10 (34).

Significance of the mean effect of each covariate [age, age2, sex, sex x age2, height (crown-rump length in baboons), and weight] was assessed using a likelihood ratio test. This test compares differences in the likelihoods of a restricted model, in which the mean effect of the covariate to be tested is constrained to zero, and a general model, in which all parameters are estimated, to the {chi}2 distribution with 1 df. If the model including the covariate effect was marginally significantly better than the model without it (P < 0.10), then the covariate was included in the final model. Reported h2 is residual heritability (that part of the variance that is attributable to the additive effects of genes after covariate effects are removed).

To control for the overall false positive rate given the finite marker locus density in the baboon genome linkage map, we estimated the LOD score associated with a genome-wide P value of 0.05 by means of a method suggested by Feingold et al. (35) At LOD more than 2.69, the genome-wide P value was <0.05. Therefore, we employ LOD equalling 2.7 as the threshold for genome-wide significance (at {alpha} = 0.05).


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Table 1Go presents the descriptive statistics for forearm BMD in these baboons by sex. Although the data in this table are from related individuals, and tests of significance that do not account for this fact are inappropriate, these summaries are presented to provide a general appreciation of the population of study animals. The study population is characterized in detail elsewhere (24). Mean aBMD in females is less than that for males at all sites. The mean age for females (12.71 yr) is slightly older than that for males (9.86 yr). Developmentally, these mean ages are roughly equivalent to those of an adult human in the 4th decade of life. Females are generally smaller than males, as indicated by height and body weight, which is to be expected in this sexually dimorphic species.


View this table:
[in this window]
[in a new window]
  		TABLE 1. Descriptive statistics for forearm aBMD and for covariates by sex

 
Table 2Go shows significant covariates and estimates of residual heritability for each site. Our analysis indicates that forearm aBMD is heritable in these baboons. Thirty-five percent of the residual variance (that portion of the variance that remains after accounting for covariate effects) in ultradistal radius aBMD (h2 = 0.35 ± 0.07, P < 0.0001) and 42% of the variance in radius 1/3 aBMD (h2 = 0.42 ± 0.08, P < 0.0001) are accounted for by the additive effects of genes. Heritability is lower in the ulna, for which 18% (h2 = 0.18 ± 0.07, P = 0.0001) of the residual variance in aBMD is due to genetic effects.


View this table:
[in this window]
[in a new window]
  		TABLE 2. Heritability estimates and significant covariates and covariate interactions included in maximum-likelihood models and genome-wide linkage screens

 
With the exception of the mildest osteophytosis score (ost_1), each of the potential covariates exerted a significant mean effect on at least one of the forearm measurement sites. Together, these covariates account for 16–32% (c2) of the total phenotypic variance in aBMD at the three forearm sites.

Figures 2–4GoGoGo present the genome-wide linkage results for ultradistal radius, radius 1/3, and ulna 1/3, respectively. The highest LOD score for each phenotype (3.11 for ultradistal radius, 3.00 for radius 1/3, and 1.95 for ulna 1/3) occurred on chromosome 11q (Pha 14) at points approximately 60–61 cM from the pter-most marker (see Fig. 5Go), with a peak in the area of markers D11S1329, D11S1338, and D11S916. For our baboon map, the 95% confidence interval includes an area 0.8340 below the peak LOD score. Focusing on the two peaks that reach statistical significance (those for the two radius sites), the 95% confidence interval for the ultradistal radius is a region extending from approximately 51–100 cM from the pter-most marker. This 49-cM region includes the following markers [physical location in humans (megabase pairs from pter) in parentheses]: D11S4200 (34), D11S904 (26), D11S1349 (11), D11S1329 (10), D11S1338 (5), D11S916 (73), D11S1902 (74), D11S1352 (78), D11S2002 (79), and D11S1366 (96). For the radius 1/3, the 95% confidence interval is a 16-cM interval extending from approximately 47–66 cM from the pter-most marker. This region includes all of the markers listed for the ultradistal radius 95% confidence interval, with the exception of D11S1366. The estimated effect sizes for the QTLs (h2Q) are 0.29 for the ultradistal radius, 0.30 for the radius 1/3, and 0.16 for the ulna 1/3. These values are 83, 71, and 89% of the entire additive genetic effect for the ultradistal radius, the radius 1/3, and the ulna 1/3, respectively. A post hoc pedigree-specific LOD score evaluation reveals that no single pedigree or sire line accounts for more than 38% of the total significant LOD scores for these traits; at least seven of the 11 pedigrees contribute positively to their LODs, with the highest LOD coming from a different pedigree in each case.



View larger version (15K):
[in this window]
[in a new window]
  		FIG. 2. Genome-wide linkage results for aBMD of the ultradistal radius.

 


View larger version (16K):
[in this window]
[in a new window]
  		FIG. 3. Genome-wide linkage results for aBMD of the radius 1/3.

 


View larger version (15K):
[in this window]
[in a new window]
  		FIG. 4. Genome-wide linkage results for aBMD of the ulna 1/3.

 


View larger version (18K):
[in this window]
[in a new window]
  		FIG. 5. Linkage of forearm aBMD to markers on chromosome 11.

 
A second, smaller peak is apparent for each phenotype around a point 92 cM from the pter-most marker. A sequential oligogenic linkage scan that accounts for the variance due to the highest peak (that one 60–61 cM from the pter-most marker) results in a reduction of this second peak to a LOD of 0.7–0.8 for all three phenotypes. This indicates that although there may be another QTL in this location that influences aBMD in the forearm, the evidence for it is not statistically significant.

Although no other chromosomal regions yielded a LOD greater than 2.69 (our genome-wide significance level at P = 0.05), several regions showed LOD scores greater than 1.0 including chromosomes 2q (Pha 12) (ultradistal radius, LOD 1.11; radius 1/3, LOD 1.91), 4p (Pha 5p) (ultradistal radius, LOD 1.20; radius 1/3, LOD 1.65), 7_21p (Pha 3p) (ultradistal radius, LOD 1.40; radius 1/3, LOD 1.06), and 7_21q (Pha 3q) (radius 1/3, LOD 1.47; ulna 1/3, LOD 1.16).


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The results of this study of the genetics of aBMD in pedigreed baboons lend further support to this species as an animal model for human bone maintenance and turnover. Just as has been reported for humans, a significant proportion of the variance in forearm aBMD in baboons is attributable to the additive effects of genes, although the heritability estimates are lower than those reported in some human studies. Differences in methodology and sample constituency between those studies and ours may contribute in part to these differences. Many studies of BMD in humans are limited to one sex or the other or to a narrower range of adult ages. Estimates of heritability based on a sample limited to one stage of skeletal development or aging or that is limited to one sex or the other may differ from those based on a more inclusive sample incorporating all stages of skeletal ontogenesis and both sexes because of differences in the phenotypic variance and/or because of genetic effects that are sex- or developmental stage-specific. Nevertheless, our modest heritability estimates were sufficient to enable detection of significant evidence for linkage.

This first genome-wide linkage scan in a nonhuman primate for QTLs affecting aBMD provides cross-species replication, in the form of significant evidence for linkage, of a QTL on chromosome 11q (Pha 14), a region that has received considerable attention in humans. This region, specifically 11q12-13, harbors the LRP5 gene and the T-cell immune regulator 1 (TCIRG1) gene, mutations of which are associated with the Mendelian disorders of the skeleton mentioned in the introduction. Naturally, this has prompted study into whether or not these same genes, or others in the region, might also contribute significantly to normal population level variation in BMD. Indeed, there is mounting evidence that this may be the case. Although not all published investigations of linkage between 11q12-13 and normal variation in bone phenotypes have found such (36), several studies report suggestive to significant evidence for linkage or association with genetic markers in this region. These include a QTL affecting femoral neck and lumbar spine aBMD in a Caucasian and African-American sample (16, 19), suggestive evidence of linkage with low aBMD in an Irish sample (18), evidence for association with radiographically assessed BMD of hand phalanges in a Chuvasha population (17), and suggestive evidence for association with metacarpal cortical index in a Chuvasha sample (37). Investigations of specific genes in this area have only just begun. A recent report indicates that particular LRP5 polymorphisms are associated with lumbar spine bone mineral content, bone area, and vertebral bone growth, particularly in males (20). Koay et al. (38) identified three single-nucleotide polymorphisms in the LRP5 gene that show significant associations with aBMD in their Caucasian sample. Another study found evidence of linkage between femoral neck aBMD and TCIRG1 but no evidence of association with polymorphisms in this gene (39).

Recent investigations of the relationship between LRP5 and mechanosensation are interesting in light of our finding of an 11q12-13 QTL in the forearm, a load-bearing site in the baboon. We did not find a QTL in this location for BMD of the spine (our unpublished data), a site that is subject to less mechanical loading in this locomotor quadruped. LRP5 is a coreceptor for Wnt, and recent research indicates that the role of Wnt/LRP5 signaling in the regulation of bone mass is linked to activation of this pathway through mechanical loading (40). Intensive and ongoing studies of the molecular mechanism by which a G171V mutation (41) in the LRP5 gene (using transgenic mice) regulates bone mass indicate that the high bone mass in individuals with this mutation results from decreased osteoblast and osteocyte apoptosis, increased bone formation in response to mechanical loading due to a lower threshold of sensitivity to mechanosensation, and potentially to reduced osteoclastogenesis (40). If LRP5 is indeed the candidate gene responsible for our linkage signal, the mediation of bone mass by LRP5 through increased bone formation in areas of greater mechanical loading could explain our detection of this effect in the baboon forearm.

Our results demonstrate that there is a gene (or genes) in this area that is very important to normal variation in forearm aBMD in this population of baboons. The effect size of the 11q12-13 QTL we report accounts for a very large portion of the total genetic effect (83, 71, and 89% for the ultradistal radius, radius 1/3, and ulna 1/3, respectively). Moreover, because our post hoc pedigree-specific LOD analysis shows that the LOD score we obtained stems from multiple pedigrees in the sample, rather than coming primarily from one or two pedigrees, we conclude it is unlikely that the detected QTL represents a single mutation with a major effect segregating through the baboon population. This QTL is in the same location that has been found to influence normal variation in BMD in humans at other skeletal sites (femoral neck and spine). This apparent conservation of function to the same genomic region attests to the overall importance of this region to human skeletal biology and, indeed, to primate skeletal biology in general. The fact that a QTL affecting BMD in inbred mice also maps to 11q12-13 may mean that this region is important beyond the primate order (42).

We cannot, of course, at this point, attribute the QTL effect to any particular gene. Although we consider LRP5 and TCIRG1 to be likely candidate genes responsible for the linkage to 11q12-13, there are other potential candidates in this region. These include FOS-like antigen 1 (FOSL1), latent transforming growth factor ß-binding protein (LTBP3), and fibronectin like 2 (FNL2) protein. Mice without FOS develop osteopetrosis due to a differentiation block in the osteoclast lineage (43). FOSL1 showed the highest rescue activity in a study of retroviral gene transfer of FOS genes that resulted in rescue of differentiation blocks in vitro, and a transgene expressing FOSL1 rescued the osteopetrosis of the mice lacking FOS (44). LTBP3 is a part of the biologically inactive large latent complex in which TGF-ß, a known stimulator of bone formation (45), is secreted, and affects TGF-ß bioavailability (46). FNL2 has not itself been directly shown to affect bone tissue, but fibronectin is an osteoid scaffolding protein and a downstream direct transcriptional target of the Wnt signaling pathway (47) and is found at elevated levels in serum in a high bone mass kindred (41).

Ultimately, the value of this study lies in its contribution to a growing body of data indicating that intensive investigation of genes in the 11q12-13 region is warranted because a gene or genes in this area affect not only extreme disorders of BMD but also normal variation in this fracture risk-related phenotype. Only after we successfully identify the gene and polymorphisms in this region that affect BMD can we screen individuals for the functional polymorphisms. Such screening would provide a mechanism for earlier identification of those at greatest risk of osteoporosis, allowing for earlier and more efficacious treatment and intervention. Given its current state of genetic characterization, the baboon provides an animal model for generating and testing hypotheses involving human skeletal genetics that is more directly biologically relevant than rodent models. Also, relative to humans, the baboon is a more accessible and less expensive model for testing the effects of potential treatment and intervention strategies on bone maintenance and turnover.


   Acknowledgments
 
We thank G. Joslyn and J. Lichter (formerly of Sequana Therapeutics, Inc.), K. D. Carey, K. S. Rice, W. Hodgson, E. Windhorst, T. Riley, D. E. Newman, N. J. Whittam, N. Stowell, S. Nair, and S. H. Slifer for technical contributions and support. We also thank C. Kammerer for discussions regarding bone studies in these baboons.


   Footnotes
 
This work was supported by a collaborative research contract with AxyS Pharmaceuticals, Inc. (formerly Sequana Therapeutics, Inc.) and by the National Institutes of Health (Grants F32 AR049694, R01 HL54141, R01 RR008781, R01 MH059490, P51 RR013986, CO6 RR013556, and P01 HL028972).

First Published Online March 8, 2005

Abbreviations: aBMD, Areal bone mineral density; DXA, dual-energy x-ray absorptiometry; IBD, identity-by-descent; LRP5, lipoprotein receptor-related protein 5; QTL, quantitative trait locus; STR, short tandem repeat.

Received August 19, 2004.

Accepted March 2, 2005.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Blank RD 2001 Breaking down bone strength: a perspective on the future of skeletal genetics. J Bone Miner Res 16:1207–1211[CrossRef][Medline]
  2. Hui SL, Slemenda CW, Johnston Jr CC 1988 Age and bone mass as predictors of fracture in a prospective study. J Clin Invest 81:1804–1809
  3. Black DM, Cummings SR, Genant HK, Nevitt MC, Palermo L, Browner W 1992 Axial and appendicular bone density predict fractures in older women. J Bone Miner Res 7:633–638[Medline]
  4. Ammann P, Rizzoli R 2003 Bone strength and its determinants. Osteoporos Int 14(Suppl 3):S13–S18
  5. Stone KL, Seeley DG, Lui LY, Cauley JA, Ensrud K, Browner WS, Nevitt MC, Cummings SR 2003 BMD at multiple sites and risk of fracture of multiple types: long-term results from the Study of Osteoporotic Fractures. J Bone Miner Res 18:1947–1954[CrossRef][Medline]
  6. Melton 3rd LJ, Atkinson EJ, O’Fallon WM, Wahner HW, Riggs BL 1993 Long-term fracture prediction by bone mineral assessed at different skeletal sites. J Bone Miner Res 8:1227–1233[Medline]
  7. Obermayer-Pietsch B, Chararas C, Kotschan S, Walter D, Leb G 2000 Genetic background of osteoporosis. Acta Med Austriaca 27:18–22[Medline]
  8. Peacock M, Turner CH, Econs MJ, Foroud T 2002 Genetics of osteoporosis. Endocr Rev 23:303–326[Abstract/Free Full Text]
  9. Beamer WG, Shultz KL, Donahue LR, Churchill GA, Sen S, Wergedal JR, Baylink DJ, Rosen CJ 2001 Quantitative trait loci for femoral and lumbar vertebral bone mineral density in C57BL/6J and C3H/HeJ inbred strains of mice. J Bone Miner Res 16:1195–1206[CrossRef][Medline]
  10. Turner CH, Hsieh YF, Muller R, Bouxsein ML, Rosen CJ, McCrann ME, Donahue LR, Beamer WG 2001 Variation in bone biomechanical properties, microstructure, and density in BXH recombinant inbred mice. J Bone Miner Res 16:206–213[CrossRef][Medline]
  11. Johnson ML, Gong G, Kimberling W, Recker SM, Kimmel DB, Recker RB 1997 Linkage of a gene causing high bone mass to human chromosome 11 (11q12-13). Am J Hum Genet 60:1326–1332[Medline]
  12. Little RD, Carulli JP, Del Mastro RG, Dupuis J, Osborne M, Folz C, Manning SP, Swain PM, Zhao SC, Eustace B, Lappe MM, Spitzer L, Zweier S, Braunschweiger K, Benchekroun Y, Hu X, Adair R, Chee L, FitzGerald MG, Tulig C, Caruso A, Tzellas N, Bawa A, Franklin B, McGuire S, Nogues X, Gong G, Allen KM, Anisowicz A, Morales AJ, Lomedico PT, Recker SM, Van Eerdewegh P, Recker RR, Johnson ML 2002 A mutation in the LDL receptor-related protein 5 gene results in the autosomal dominant high-bone-mass trait. Am J Hum Genet 70:11–19[CrossRef][Medline]
  13. Gong Y, Slee RB, Fukai N, Rawadi G, Roman-Roman S, Reginato AM, Wang H, Cundy T, Glorieux FH, Lev D, Zacharin M, Oexle K, Marcelino J, Suwairi W, Heeger S, Sabatakos G, Apte S, Adkins WN, Allgrove J, Arslan-Kirchner M, Batch JA, Beighton P, Black GC, Boles RG, Boon LM, Borrone C, Brunner HG, Carle GF, Dallapiccola B, De Paepe A, Floege B, Halfhide ML, Hall B, Hennekam RC, Hirose T, Jans A, Juppner H, Kim CA, Keppler-Noreuil K, Kohlschuetter A, LaCombe D, Lambert M, Lemyre E, Letteboer T, Peltonen L, Ramesar RS, Romanengo M, Somer H, Steichen-Gersdorf E, Steinmann B, Sullivan B, Superti-Furga A, Swoboda W, van den Boogaard MJ, Van Hul W, Vikkula M, Votruba M, Zabel B, Garcia T, Baron R, Olsen BR, Warman ML 2001 LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development. Cell 107:513–523[CrossRef][Medline]
  14. Heaney C, Shalev H, Elbedour K, Carmi R, Staack JB, Sheffield VC, Beier DR 1998 Human autosomal recessive osteopetrosis maps to 11q13, a position predicted by comparative mapping of the murine osteosclerosis (oc) mutation. Hum Mol Genet 7:1407–1410[Abstract/Free Full Text]
  15. Van Hul E, Gram J, Bollerslev J, Van Wesenbeeck L, Mathysen D, Andersen PE, Vanhoenacker F, Van Hul W 2002 Localization of the gene causing autosomal dominant osteopetrosis type I to chromosome 11q12-13. J Bone Miner Res 17:1111–1117[CrossRef][Medline]
  16. Koller DL, Econs MJ, Morin PA, Christian JC, Hui SL, Parry P, Curran ME, Rodriguez LA, Conneally PM, Joslyn G, Peacock M, Johnston CC, Foroud T 2000 Genome screen for QTLs contributing to normal variation in bone mineral density and osteoporosis. J Clin Endocrinol Metab 85:3116–3120[Abstract/Free Full Text]
  17. Livshits G, Trofimov S, Malkin I, Kobyliansky E 2002 Transmission disequilibrium test for hand bone mineral density and 11q12-13 chromosomal segment. Osteoporos Int 13:461–467[CrossRef][Medline]
  18. Wynne F, Drummond FJ, Daly M, Brown M, Shanahan F, Molloy MG, Quane KA 2003 Suggestive linkage of 2p22-25 and 11q12-13 with low bone mineral density at the lumbar spine in the Irish population. Calcif Tissue Int 72:651–658[CrossRef][Medline]
  19. Koller DL, Rodriguez LA, Christian JC, Slemenda CW, Econs MJ, Hui SL, Morin P, Conneally PM, Joslyn G, Curran ME, Peacock M, Johnston CC, Foroud T 1998 Linkage of a QTL contributing to normal variation in bone mineral density to chromosome 11q12-13. J Bone Miner Res 13:1903–1908[CrossRef][Medline]
  20. Ferrari S, Deutsch S, Choudhury U, Chevalley T, Bonjour J, Dermitzakis E, Rizzoli R, Antonarakis S 2004 Polymorphisms in the low-density lipoprotein receptor-related protein 5 (LRP5) gene are associated with variation in vertebral bone mass, vertebral bone size, and stature in whites. Am J Hum Genet 74:866–875[CrossRef][Medline]
  21. Jerome CP, Peterson PE 2001 Nonhuman primate models in skeletal research. Bone 29:1–6[Medline]
  22. Aufdemorte TB, Fox WC, Miller D, Buffum K, Holt GR, Carey KD 1993 A non-human primate model for the study of osteoporosis and oral bone loss. Bone 14:581–586[Medline]
  23. Kammerer CM, Sparks ML, Rogers J 1995 Effects of age, sex, and heredity on measures of bone mass in baboons (Papio hamadryas). J Med Primatol 24:236–242[Medline]
  24. Havill LM, Mahaney MC, Czerwinski SA, Carey KD, Rice K, Rogers J 2003 Bone mineral density reference standards in adult baboons (Papio hamadryas) by sex and age. Bone 33:877–888[Medline]
  25. Chen LD, Kushwaha RS, McGill Jr HC, Rice KS, Carey KD 1998 Effect of naturally reduced ovarian function on plasma lipoprotein and 27-hydroxycholesterol levels in baboons (Papio sp.). Atherosclerosis 136:89–98[CrossRef][Medline]
  26. Martin LJ, Carey KD, Comuzzie AG 2003 Variation in menstrual cycle length and cessation of menstruation in captive baboons. Mech Ageing Dev 124:865–871[CrossRef][Medline]
  27. Rogers J, Mahaney MC, Witte SM, Nair S, Newman D, Wedel S, Rodriguez LA, Rice KS, Slifer SH, Perelygin A, Slifer M, Palladino-Negro P, Newman T, Chambers K, Joslyn G, Parry P, Morin PA 2000 A genetic linkage map of the baboon (Papio hamadryas) genome based on human microsatellite polymorphisms. Genomics 67:237–247[CrossRef][Medline]
  28. Vagtborg H 1973 The story of the Southwest Research Center: a private, nonprofit scientific research adventure. Austin: University of Texas Press
  29. Council NR 1996 Guide for the care and use of laboratory animals. Washington, DC: National Academy of Sciences
  30. Matise TC, Schroeder MD, Chiarulli DM, Weeks DE 1995 Parallel computation of genetic likelihoods using CRI-MAP, PVM, and a network of distributed workstations. Hum Hered 45:103–116[Medline]
  31. Matise TC, Perlin M, Chakravarti A 1994 Automated construction of genetic linkage maps using an expert system (MultiMap): a human genome linkage map. Nat Genet 6:384–390[CrossRef][Medline]
  32. Almasy L, Blangero J 1998 Multipoint quantitative-trait linkage analysis in general pedigrees. Am J Hum Genet 62:1198–1211[CrossRef][Medline]
  33. Fulker DW, Cherny SS, Cardon LR 1995 Multipoint interval mapping of quantitative trait loci, using sib pairs. Am J Hum Genet 56:1224–1233[Medline]
  34. Ott J 1988 Analysis of human genetic linkage. Baltimore and London: The Johns Hopkins University Press
  35. Feingold E, Brown PO, Siegmund D 1993 Gaussian models for genetic linkage analysis using complete high-resolution maps of identity by descent. Am J Hum Genet 53:234–251[Medline]
  36. Deng HW, Xu FH, Conway T, Deng XT, Li JL, Davies KM, Deng H, Johnson M, Recker RR 2001 Is population bone mineral density variation linked to the marker D11S987 on chromosome 11q12-13? J Clin Endocrinol Metab 86:3735–3741[Abstract/Free Full Text]
  37. Cohen Z, Kalichman L, Kobyliansky E, Malkin I, Almog E, Livshits G 2003 Cortical index and size of hand bones: segregation analysis and linkage with the 11q12-13 segment. Med Sci Monit 9:MT13–MT20
  38. Koay MA, Woon PY, Zhang Y, Miles LJ, Duncan EL, Ralston SH, Compston JE, Cooper C, Keen R, Langdahl BL, MacLelland A, O’Riordan J, Pols HA, Reid DM, Uitterlinden AG, Wass JA, Brown MA 2004 Influence of LRP5 polymorphisms on normal variation in BMD. J Bone Miner Res 19:1619–1627[CrossRef][Medline]
  39. Carn G, Koller DL, Peacock M, Hui SL, Evans WE, Conneally PM, Johnston Jr CC, Foroud T, Econs MJ 2002 Sibling pair linkage and association studies between peak bone mineral density and the gene locus for the osteoclast-specific subunit (OC116) of the vacuolar proton pump on chromosome 11p12-13. J Clin Endocrinol Metab 87:3819–3824[Abstract/Free Full Text]
  40. Johnson ML 2004 The high bone mass family: the role of Wnt/Lrp5 signaling in the regulation of bone mass. J Musculoskelet Neuronal Interact 4:135–138[Medline]
  41. Boyden LM, Mao J, Belsky J, Mitzner L, Farhi A, Mitnick MA, Wu D, Insogna K, Lifton RP 2002 High bone density due to a mutation in LDL-receptor-related protein 5. N Engl J Med 346:1513–1521[Abstract/Free Full Text]
  42. Klein RF, Mitchell SR, Phillips TJ, Belknap JK, Orwoll ES 1998 Quantitative trait loci affecting peak bone mineral density in mice. J Bone Miner Res 13:1648–1656[CrossRef][Medline]
  43. Johnson RS, Spiegelman BM, Papaioannou V 1992 Pleiotropic effects of a null mutation in the c-fos proto-oncogene. Cell 71:577–586[CrossRef][Medline]
  44. Matsuo K, Owens JM, Tonko M, Elliott C, Chambers TJ, Wagner EF 2000 Fosl1 is a transcriptional target of c-Fos during osteoclast differentiation. Nat Genet 24:184–187[CrossRef][Medline]
  45. Bonewald LF, Dallas SL 1994 Role of active and latent transforming growth factor beta in bone formation. J Cell Biochem 55:350–357[CrossRef][Medline]
  46. Oklu R, Hesketh R 2000 The latent transforming growth factor beta binding protein (LTBP) family. Biochem J 352:601–610
  47. Gradl D, Kuhl M, Wedlich D 1999 The Wnt/Wg signal transducer beta-catenin controls fibronectin expression. Mol Cell Biol 19:5576–5587[Abstract/Free Full Text]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Reprints, Permissions and Rights
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Havill, L. M.
Right arrow Articles by Rogers, J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Havill, L. M.
Right arrow Articles by Rogers, J.
Related Collections
Right arrow Calcium and Bone Metabolism

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals