ビタミンD受容体の遺伝子多型と骨密度の関係 縦断分析による長期橈骨骨密度推移の検討

摘要

Recent studies have shown that genetic effects on bone mineral density (BMD) and bone turnover are related to vitamin D receptor (VDR) gene polymorphism. However,discordant studies have been published and it is still not clear whether VDR genotypes influence bone mass accretion and/or postmeno-pausal bone loss. To assess allelic influence of the VDR gene on BMD, we determined changes in 1/6-radial-BMD by several repeat measurements in the same subjects for about ten years and analyzed VDR polymorphism of Bsml restriction enzyme in 53 normal healthy Japanese women (age:50.3+-4.7 years,mean+-SD).Twenty-seven (age:53.2+-4.7 years) of the subjects were post-menopausal (POST group).Among these 53 subjects,the distribution of bb,Bb and BB genotypes was 64.2%,34% and 1.9%, respectively.The genotype frequencies in this study were very similar to those in previous reports concerning other Japanese women.There was no difference between the b group (women with bb genotype) and B group (women with BB or Bb genotype) in age,body weight,height,body mass index (BMI),years since menopause,serum osteocalcin and serum alkaline phosphatase values.In the POST group, BMD of the B group at menopause was lower than that of the b group (p<0.05).About ten years after menopause,BMD did not differ significantly between these groups Because the decrease in BMD in the b group was larger than that in the B group. Regarding changes in BMD in the POST group for four years after menopause,BMD of the b group was significantly decreased compared with the B group (p<0.01).Our findings suggest that the differences in BMD by VDR genotype were larger among pre- and pri-menopausal women and seemed to decrease with years after menopause.It is suggested that there are other factors influencing BMD and postmenopausal bone loss in elderly women.