The association between postmenopausal vertebral bone mineral density and estrogen receptor gene alleles in ethnic Japanese living in Western Japan

Bone mass and its mineral content has been shown to be under genetic contro l. Our purpose in this study was to assess whether estrogen receptor genoty pes influence changes in bone mass in post menopausal Japanese women and cl arify the regional differences in Japanese women. Pvu II and Xba I restrict ion enzyme fragment length polymorphism of the estrogen receptor gene and i ts relationship with vertebral bone mineral density were examined in 300 un related post menopausal women, aged 42-69 years, from the Kinki region in J apan. Vertebral bone mineral density was evaluated at the lumbar spine (L2- 4) by dual energy X-ray absorptiometry. We found no relationship between an y single restriction site polymorphism and the Z-score of bone mineral dens ity. However, the allelic haplotype PPXx was found to be associated with a significantly low bone mineral density (Z-score for the lumbar spine -1.118 +/- 1.270 vs. PPxx 0.04 +/- 1.150; p<0.01, vs. ppxx 0.387 <plus/minus> 1.2 26; p<0.05, respectively). We suggest that ER gene polymorphism is associated with low bone mineral de nsity and that this partly explains the cause of post menopausal bone loss in Japanese women. The contradictory conclusions compared with previous stu dies in the Japanese population regarding the association of BMD with ER RF LPs demands further investigation.