Taes Youri E C, Goemaere Stefan, Huang Guangming, Van Pottelbergh Inge, De Bacquer Dirk, Verhasselt Bruno, Van den Broeke Celine, Delanghe Joris R, Kaufman Jean-Marc
Laboratory of Clinical Chemistry, Microbiology and Immunology 2P8, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
Bone. 2006 May;38(5):701-7. doi: 10.1016/j.bone.2005.10.006. Epub 2005 Nov 22.
The vitamin D binding protein (DBP) is the major carrier protein for vitamin D metabolites in plasma. Polymorphisms in DBP have been described to be associated with an increased bone fracture risk and diabetes. The present study investigates the influence of both phenotypic and (TAAA)(n)-Alu repeat DBP-polymorphism and DBP-concentration on bone mineral density, body composition, bone turnover- and metabolic markers in a cohort of ambulatory elderly men. We included 211 men (>70 years) in this study. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. Bone turnover was assessed by measurement of serum osteocalcin, serum and urinary C-terminal telopeptides of type I collagen and urinary deoxypyridinoline, together with 25(OH)-vitamin D and 1,25(OH)(2)-vitamin D concentrations. DBP-phenotypes were determined electrophoretically and the (TAAA)(n)-Alu repeat polymorphism was determined by polymerase chain reaction. Body composition was estimated using bioelectrical impedance analysis, together with handgrip and arm strength, fasting serum glucose and leptin concentrations. No differences in BMD or bone turnover markers among DBP-phenotypes or (TAAA)(n)-genotypes were observed in this study. Serum 25(OH)-vitamin D was comparable among DBP-variants and did not relate to DBP-concentrations, whereas 1,25(OH)(2)-vitamin D was different among DBP-phenotypes and was correlated positively with DBP-concentrations. DBP-concentrations related positively to body mass index, fat mass, leptin and glucose concentration. The correlation with leptin remained significant after correction for fat mass. Fasting glucose concentrations were different among DBP-phenotypes, whereas no difference was observed between (TAAA)(n)-genotypes. In conclusion, serum 1,25(OH)(2)-vitamin D concentrations are codetermined by DBP-phenotypes and DBP-concentrations. No major effect of DBP-polymorphism was demonstrated on BMD, bone turnover markers or body composition.
维生素D结合蛋白（DBP）是血浆中维生素D代谢产物的主要载体蛋白。DBP的多态性已被描述为与骨折风险增加和糖尿病有关。本研究调查了表型和（TAAA）（n）-Alu重复DBP多态性以及DBP浓度对一组门诊老年男性骨密度、身体成分、骨转换和代谢标志物的影响。我们纳入了211名男性（年龄>70岁）进行本研究。通过双能X线吸收法测定骨密度。通过测量血清骨钙素、血清和尿I型胶原C末端肽以及尿脱氧吡啶啉，同时测定25（OH）-维生素D和1,25（OH）₂-维生素D浓度来评估骨转换。通过电泳确定DBP表型，通过聚合酶链反应确定（TAAA）（n）-Alu重复多态性。使用生物电阻抗分析以及握力和臂力、空腹血清葡萄糖和瘦素浓度来估计身体成分。在本研究中，未观察到DBP表型或（TAAA）（n）-基因型之间骨密度或骨转换标志物的差异。血清25（OH）-维生素D在DBP变体之间具有可比性，且与DBP浓度无关，而1,25（OH）₂-维生素D在DBP表型之间存在差异，并且与DBP浓度呈正相关。DBP浓度与体重指数、脂肪量、瘦素和葡萄糖浓度呈正相关。校正脂肪量后，与瘦素的相关性仍然显著。空腹血糖浓度在DBP表型之间存在差异，而在（TAAA）（n）-基因型之间未观察到差异。总之，血清1,25（OH）₂-维生素D浓度由DBP表型和DBP浓度共同决定。未证明DBP多态性对骨密度、骨转换标志物或身体成分有主要影响。
