Aim: To establish personalized treatment of osteoporosis.
Methods: A T869-->C polymorphism in exon 1 of the transforming growth factor-beta1 gene, which results in a Leu-->Pro substitution at amino acid 10, is reported to be associated with the rate of bone loss as well as the response to active vitamin D treatment. Therefore, we determined this single nucleotide polymorphism (SNP) to estimate the need of active vitamin D treatment. We also determined serum level of 25 hydroxy-vitamin D to evaluate a degree of vitamin D fulfillment. Based on these data, we categorized postmenopausal patients into four groups; C homozygote with vitamin D deficiency patients to whom 1 microg/day active vitamin D was administered, C homozygote without vitamin D deficiency patients or those who bore at least one T-allele with vitamin D deficiency to whom 0.5 microg/day active vitamin D was administered, and patients who bore at least one T-allele without vitamin D deficiency to whom no drug was given. The patients were checked up every 6 months with regard to changes in bone mineral density and occurrence of fresh fractures.
Results: The SNP was associated with prevalent vertebral fractures; the frequency of the T allele was significantly greater in patients with vertebral fractures. Furthermore, the serum level of 25 hydroxy-vitamin D was significantly lower in patients with vertebral fractures, which were observed in 17 out of 34 patients who bore at least one T-allele as well as vitamin D deficiency, while only 2 of 15 homozygous C-allele carriers without vitamin D deficiency suffered from fractures.
Conclusion: These findings suggest that the SNP in combination with the serum level of 25 hydroxy-vitamin D can predict fracture risk in postmenopausal osteoporosis.