This largest-ever population study using MRI to define DDD demonstrates for the first time that the Trp2 allele is a significant risk factor for the development and severity of degeneration. The association is age- dependent as it is more prevalent in some age groups than in others. The contrasting Trp allele frequencies between the Finns and the Chinese are the first indication that the genetic risk factors for DDD varies between ethnic groups.

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.

This is the first study to demonstrate an association between the Trp2 allele and disc mechanics, thus relating genetic variations and debilitating mechanical alterations that may ultimately result in intervertebral disc degeneration.