Background: Patients with COPD are at an increased risk of osteoporosis. Although many studies have addressed the relationship between the vitamin D receptor (VDR) polymorphisms and bone health, this relationship has not been fully investigated in patients with COPD. In this study, we investigated the association of VDR polymorphisms with bone mineral density (BMD) and other clinical parameters in patients with COPD.
Patients and methods: In total, 200 patients with COPD were included in this study. The VDR polymorphisms rs1544410 (A/G-BsmI), rs7975232 (A/C-ApaI), rs731236 (C/T-TaqI), and rs10735810 (C/T-FokI) were determined by Sanger sequencing using blood DNA samples. BMD of the lumbar vertebra and the femoral neck was measured by dual-energy X-ray absorptiometry. Other clinical parameters were also evaluated. Haplotype and multivariate analyses were also performed.
Results: Sex, body mass index, steroid use, percentage of forced expiratory volume in 1 second (FEV1), alkaline phosphatase, and 25-hydroxyvitamin D significantly influenced the risk of osteoporosis. Patients with osteoporosis were more likely to carry the rs7975232 C allele compared to normal patients with BMD. Haplotypes GCT and GAT were related to osteoporosis. Patients without the haplotype GAT allele showed a significantly lower T-score at the femoral neck and an increased risk of osteoporosis (odds ratio [OR]= 2.78, 95% confidence interval [CI]= 1.20-6.48, P=0.018) compared with carriers in the dominant model.
Conclusion: Genetic variations in VDR are significantly associated with osteoporosis among patients with COPD. Further studies are required to confirm the role of the VDR polymorphisms in osteoporosis among patients with COPD.
Keywords: chronic obstructive pulmonary disease; haplotype; osteoporosis; polymorphism; vitamin D receptor gene.