Association Between the Aggrecan Gene Variable Number of Tandem Repeats Polymorphism and Intervertebral Disc Degeneration

Study Design: Cross-sectional study.

Objective: To examine the association between an aggrecan variable number of tandem repeats (VNTR) polymorphism and intervertebral disc degeneration in middle-aged Finnish men.

Summary Of Background Data: An association between the aggrecan VNTR polymorphism and multilevel disc degeneration has been previously reported in young Japanese women.

Methods: Lumbar discs of 132 men representing 3 occupations (carpenters, machine drivers, and office workers) were evaluated on magnetic resonance imaging, using decreased signal intensity of the nucleus pulposus, disc bulges, and decreased disc height as signs of degeneration. The aggrecan gene VNTR region was analyzed by Southern hybridization.

Results: The allele A26 with 26 repeats was statistically significantly overrepresented among the persons with dark nucleus pulposus. Carrying 2 copies of the A26 allele increased the risk of dark nucleus pulposus (odds ratio = 2.77; 95% confidence interval, 1.24-6.16). Carrying the alleles with either less or more than 26 repeats decreased the risk of dark nucleus pulposus. The carpenters and machine drivers with the A26 allele had a statistically significantly higher risk of disc bulge and decreased disc height than the office workers without the allele.

Conclusion: The findings provide additional support for the role of the aggrecan gene VNTR polymorphism in intervertebral disc degeneration.