VDR and intervertebral disk degenerative disorder: A number of environmental factors such as age, obesity, excessive mechanical loading, injury, vibration, and smoking status, were reported to have an impact on disc degeneration.[38] However, more and more evidence showed that genetic factors may play a critical role in occurrence of disc degeneration.[39] Among these genetic factors, the allelic variants of the gene encoding VDR, include TaqI (rs731236), FokI (rs2228570) and ApaI (rs7975232) have been reported to be associated with disc degeneration risk.