Association Between CTSK Gene Polymorphisms and Response to Alendronate Treatment in Postmenopausal Chinese Women with Low Bone Mineral Density.

Purpose: The aim of this study was to explore the association between CTSK polymorphisms and the response to alendronate treatment in postmenopausal Chinese women with low bone mineral density.

Patients and methods: In this study, 460 postmenopausal women from Shanghai were included. All of them were treated with weekly oral alendronate 70 mg, daily calcium 600 mg and vitamin D 125 IU for a year. Four tag single nucleotide polymorphisms (SNPs) in CTSK gene were genotyped. Bone mineral densities of lumbar spine (L1-L4), femoral neck and total hip were measured at baseline and after 12 months of treatment, respectively.

Results: After 1-year of treatment, there was no significant differences in BMI between baseline and follow-up. After alendronate treatment, the BMD of L1-4, femoral neck and total hip all increased significantly (all P < 0.001), with average increases of 4.33 ± 6.42%, 1.85 ± 4.20%, and 2.36 ± 3.79%, respectively. There was no significant difference in BMD at L1-L4, the femoral neck and total hip between different genotype groups at baseline (P>0.05). After 1-year treatment with alendronate, rs12746973 and rs10847 were associated with the % change of BMD at L1-L4 (P=0.038) and % change of BMD at femoral neck (P=0.038), respectively. Furthermore, rs10847 was associated with BMD response at femoral neck (P=0.013). However, the associations were not significant after Bonferroni correction.

Conclusion: We concluded that the common variations of CTSK gene were potentially associated with the therapeutic response to alendronate treatment in Chinese women with low bone mineral density. However, further validation is needed.