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ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(1): 61–67
CN 31-1940/Q
Association between VDR ApaI Polymorphism and Hip Bone
Mineral Density Can Be Modified by Body Mass Index: A Study on Postmenopausal
Chinese Women
Hong XU1,2, Dong-Hai XIONG3, Fu-Hua XU3,
Yuan-Yuan ZHANG3, Shu-Feng LEI1, and Hong-Wen DENG1,3*
1Laboratory of Molecular and Statistical Genetics, College of Life Sciences,
Hunan Normal University, Changsha 410081, China;
2Department of Physiology, Jiangxi Medical College, Nanchang 330006,
China;
3Osteoporosis Research Center and Department of Biomedical Sciences,
Creighton University Medical Center, Omaha, NE 68131, USA
Abstract Osteoporosis
is a major public health problem for old people. Genetic factors are considered
to be major contributors to the pathogenesis of postmenopausal osteoporosis.
The vitamin D receptor (VDR) gene is a prominent candidate gene for the
regulation of postmenopausal bone mass; however, despite extensive studies,
controversy remains regarding its association with postmenopausal body mineral
density (BMD) variation. In this study, a total of 260 healthy postmenopausal
Chinese women were genotyped at the VDR ApaI locus using polymerase
chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Raw hip
BMD was significantly associated with VDR ApaI polymorphism with and
without adjusting for age (P=0.015 and 0.040, respectively). This
genetic effect can explain 3.32% of hip BMD variation. However, the significant
association vanished after correcting for both age and body mass index (BMI) (P=0.169).
In addition, we observed a significant association between VDR ApaI
polymorphism with unadjusted BMI (P=0.042) or BMI adjusted for age (P=0.049).
The raw hip BMD was also found to be significantly correlated with BMI (r=0.517,
P=0.0001), with BMI explaining 26.35% of the variation of hip BMD. All
of these facts prompt us to conclude that the significant association between
the VDR ApaI genotype and hip BMD may be modified by BMI in
postmenopausal Chinese women. Our findings may partially explain the earlier
inconsistent association results concerning the VDR gene and BMD, and highlight
the importance of incorporating covariates such as BMI into osteoporosis
association studies.
Key words body mass index (BMI); bone
mineral density (BMD); genetic association; osteoporosis; vitamin D
receptor (VDR) gene
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Received: October 18, 2004 Accepted: December 14,
2004
*Corresponding author: Tel, 86-731-8872791; Fax, 86-731-8872791;
E-mail, [email protected]