Cartilage Intermediate Layer Protein and Asporin Polymorphisms Are Independent Risk Factors of Lumbar Disc Degeneration in Male Collegiate Athletes

Objective: Lumbar disc degeneration (LDDG), recently reported to have strong genetic determinants, is a major cause of discopathy and lower back pain. However, most studies have only evaluated the effects of a single susceptibility polymorphism. Our purpose was to examine the effect of two susceptibility polymorphism for LDDG in Japanese collegiate athletes. Design: We investigated two susceptibility genes for LDDG—cartilage intermediate layer protein (CILP) and asporin (ASPN)—in 516 collegiate athletes and genotyped the risk allele of CILP (1184T/C) and ASPN (D14). LDDG was evaluated using T2-weighted magnetic resonance imaging. Results: By using logistic regression analysis, we found that the ASPN D14 allele and CILP genotype were associated with an increased risk of LDDG in male but not female athletes (CILP CT: odds ratios [OR] = 1.77, 95% confidence interval [CI] = 1.07-2.93; CILP CC: OR = 4.38, 95% CI = 1.42-13.54; ASPN D14: OR = 2.17, 95% CI = 1.10-4.28]. We also found that CILP C and ASPN D14 were independent variables. The ORs with more than two risk alleles were largely increased. Conclusions: The CILP and ASPN polymorphisms are independent genetic risk factors for LDDG in male but not female Japanese collegiate athletes.