Dataset Information

Association of DXA-derived bone mineral density and fat mass with African ancestry.

ABSTRACT: Both genes and environment have been implicated in determining the complex body composition phenotypes in individuals of European ancestry; however, few studies have been conducted in other race/ethnic groups.We conducted a genome-wide admixture mapping study in an attempt to localize novel genomic regions associated with genetic ancestry.We selected a sample of 842 African-American women from the Women's Health Initiative single nucleotide polymorphism (SNP) Health Association Resource for whom several dual-energy X-ray absorptiometry (DXA)-derived bone mineral density (BMD) and fat mass phenotypes were available.We derived both global and local ancestry estimates for each individual from Affymetrix 6.0 data and analyzed the correlation of DXA phenotypes with global African ancestry. For each phenotype, we examined the association of local genetic ancestry (number of African ancestral alleles at each marker) and each DXA phenotype at 570 282 markers across the genome in additive models with adjustment for important covariates.We identified statistically significant correlations of whole-body fat mass, trunk fat mass, and all 6 measures of BMD with a proportion of African ancestry. Genome-wide (admixture) significance for femoral neck BMD was achieved across 2 regions ?3.7 MB and 0.3 MB on chromosome 19q13; similarly, total hip and intertrochanter BMD were associated with local ancestry in these regions. Trunk fat was the most significant fat mass phenotype showing strong, but not genomewide significant associations on chromosome Xp22.Our results suggest that genomic regions in postmenopausal African-American women contribute to variance in BMD and fat mass existence and warrant further study.

SUBMITTER: Ochs-Balcom HM

PROVIDER: S-EPMC3615193 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Association of DXA-derived bone mineral density and fat mass with African ancestry.

Ochs-Balcom Heather M HM Preus Leah L Wactawski-Wende Jean J Nie Jing J Johnson Nicholas A NA Zakharia Fouad F Tang Hua H Carlson Chris C Carty Cara C Chen Zhao Z Hoffman Thomas T Hutter Carolyn M CM Jackson Rebecca D RD Kaplan Robert C RC Li Li L Liu Song S Neuhouser Marian L ML Peters Ulrike U Robbins John J Seldin Michael F MF Thornton Timothy A TA Thompson Cheryl L CL Kooperberg Charles C Sucheston Lara E LE

The Journal of clinical endocrinology and metabolism 20130222 4

<h4>Context</h4>Both genes and environment have been implicated in determining the complex body composition phenotypes in individuals of European ancestry; however, few studies have been conducted in other race/ethnic groups.<h4>Objective</h4>We conducted a genome-wide admixture mapping study in an attempt to localize novel genomic regions associated with genetic ancestry.<h4>Setting/participants</h4>We selected a sample of 842 African-American women from the Women's Health Initiative single nuc ...[more]

PMID: 23436924

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Project description:Few studies have systematically evaluated the technical aspects of forearm bone mineral density (BMD) measurement. We found that BMD remained stable regardless of the reference point; however, the ROI identified was not always consistent. Our study highlights the importance of using the same reference point for serial measurements of forearm BMD.BackgroundForearm fractures are clinically important outcomes from the perspective of morbidity, health care costs, and interruption of work. BMD of the forearm, as derived by dual-energy x-ray absorptiometry (DXA), is a better predictor of fracture at the forearm compared with BMD measured at other sites. However, very few studies have evaluated the technical aspects of selecting the ROI for forearm BMD measurement. This study aimed to compare the BMD values measured at the 1/3 radius site using three different reference points: the ulnar styloid process, the radial endplate, and the bifurcation of the ulna and radius.MethodologyHealthy Chinese patients participating in the control group of an ongoing study at Zhejiang Provincial People's Hospital were recruited for this study. For each patient, a DXA scan (GE Lunar Prodigy) of the forearm was performed and BMD values were separately calculated using each of the three reference points to identify the ROI. Pearson correlation coefficients were calculated to examine the correlation between the BMD measures derived from each reference point. The F test and independent t test were applied for more robust analysis of the differences in the variances and means.ResultsSixty-eight healthy Chinese volunteers agreed to participate in this study. The root mean square standard deviation (RMS-SD) percentages of BMD values measured at the 1/3 radius site were 2.19%, 2.23%, and 2.20% when using the ulnar styloid process, radial endplate, and the bifurcation of the ulna and radius as the reference points, respectively. Pearson's correlation coefficients for all pairwise comparisons among these three groups were greater than 0.99. F tests and independent t tests showed p values ranging from 0.92 to 0.99. However, we observed that among 10% of patients, choosing an ROI at the ulnar styloid process led to an inability to accurately determine the BMD at the ultra-distal radius.ConclusionsGiven equal ability to determine BMD at the 1/3 radius accurately, the radial endplate or the bifurcation of the ulna and radius should be preferentially selected as the reference point for routine forearm BMD measurements in order to avoid situations in which the ultra-distal radius BMD cannot be determined.

Dataset Information

Association of DXA-derived bone mineral density and fat mass with African ancestry.

Publications

Association of DXA-derived bone mineral density and fat mass with African ancestry.

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