中国老年人骨量丢失与维生素D受体基因启动子中Cdx-2结合位点的多态性

背景：骨质疏松症是一种与基因有关的骨脆性疾病，维生素D受体基因是主要候选基因之一。 目的：前瞻性调查老年人维生素D受体基因启动子中Cdx-2结合位点多态性与骨密度、骨量丢失的关系。 设计、时间及地点：前瞻性横断面调查，于2000-03/2005-03在沈阳医学院营养与食品卫生学教研室完成。 对象：选取沈阳市某社区无血缘关系、60岁以上的100名汉族健康老年人作为调查对象，性别不限，未服用过维生素D和钙补充剂，均自愿参与调查。 方法：用聚合酶链反应限制性片段长度多态性方法检测维生素D受体基因启动子中Cdx-2结合位点的多态性，应用DPX-L双能X射线吸收仪分别在调查初始和5年后两次测量调查对象的髋部骨密度。 主要观察指标：检测维生素D受体基因启动子中Cdx-2结合位点基因型分布，以协方差分析法分析维生素D受体基因启动子中Cdx-2结合位点多态性与髋部骨密度的关系。 结果：调查人群维生素D受体基因启动子中Cdx-2结合位点基因型频率分布为AA型17%，AG型57%，GG型26%；男女间等位基因型分布差异无显著性意义（P > 0.05）；该人群中等位基因频率分布符合Hardy-Weinberg 定律。无论男女各基因型间年龄、身高和体质量差异均无显著性意义（P > 0.05）。经身高、体质量和年龄校正后，调查初始不同基因型调查对象间股骨颈和大转子的骨密度差异无显著性意义（P > 0.05）；不同基因型调查对象间各部位年骨量丢失率差异也无显著性意义（P > 0.05）。 结论：调查人群维生素D受体基因启动子中Cdx-2结合位点基因型与髋部骨密度及骨量丢失无明显相关性。

Gene polymorphism in Cdx-2 binding sites of the vitamin D receptor and bone loss in the elderly in China

BACKGROUND: Osteoporosis is a bone fragility disorder with a strong genetic predisposition. The vitamin D receptor gene was one of the main candidate ones. OBJECTIVE: To investigate whether the gene polymorphism in Cdx-2 binding sites of vitamin D receptor has related to the bone mineral density (BMD) and bone loss in older adults. DESIGN, TIME AND SETTING: Prospective Longitudinal study was performed in the Department of Nutrition and Food Hygiene, Shenyang Medical College form March 2003 to March 2005 PARTICIPANTS: A total of 100 healthy unrelated individuals, over 60 years old, in Han of Shenyang were selected. They all had no history of taking vitamin D and calcium supplement. METHODS: The gene polymorphism of Cdx-2 binding sites of vitamin D receptor was measured by polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP). BMD at hip was measured using dual-energy X-ray (DPX-L) absorption apparatus (Lunar,USA) at baseline and after 5 years, respectively. MAIN OUTCOME MEASURES: The distribution of genotypes in Cdx-2 binding sites was measured. The association between the gene polymorphism of Cdx-2 combine sites of vitamin D receptor and BMD in hip were analyzed by covariance analysis. RESULTS: The frequencies of AG, GG and AA genotypes in Cdx-2 binding sites were 57 %, 26 %, and 17 %, repectively. There was no significant difference in alleles between males and females. The frequencies distribution in the population accorded with the Hardy-Weinberg equilibrium. There was no significant difference in age, height, body mass among the genotypes both in males and females. After adjusting for height, weight and age, there was no significant difference in BMD in the femoral neck and trochanter among the different genotypes, as well as the Annualized bone loss rate. CONCLUSION: The genotype in Cdx-2 binding site of vitamin D receptor did not have obviously related to BMD and bone loss at hip.