Study design: Large scale, case-control study.
Objective: To assess the effect of the Taq I alleles in vitamin D receptor on the risk of developing degenerative disc disease in a Southern Chinese population.
Summary of background data: Previous studies in Finns and Japanese suggest that the Taq I polymorphism of vitamin D receptor is associated with the development of degenerative disc disease in the lumbar spine. However, sample sizes were small, and the results need to be confirmed in other populations.
Method: Lumbar degenerative disc disease was defined by magnetic resonance imaging (MRI) on 804 Southern Chinese volunteers between 18 and 55 years of age. Restriction enzyme digestion of polymerase chain reaction products was used to analyze the Taq I alleles. The resulting genotypes were correlated with the presence of lumbar disc degeneration and bulge on MRI.
Results: Using logistic regression analysis and adjusting for age and sex, the t allele of Taq I in vitamin D receptor gene was significantly associated with degenerative disc disease, with an odds ratio (OR) of 2.61 (95% confidence interval [CI] 1.15-5.90, P = 0.041). Further subgroup analysis showed that in individuals younger than 40 years, the OR was even higher, at 5.97 (95% CI 1.69-21.15, P = 0.002). Similarly, disc bulge was significantly associated with t allele (OR = 7.17, 95% CI 1.43-36.01, P = 0.001) in individuals younger than 40 years. Anular tears and the Schmorl nodes were not associated with the t allele of Taq I polymorphism.
Conclusion: To our knowledge, this is the largest scale genetics study to date using MRI to define precisely degenerative disc disease in the Southern Chinese population. We showed that the t allele of vitamin D receptor Taq I is associated with a high risk of degenerative disc disease and disc bulge developing, especially in individuals younger than 40 years.