Abstract

Genetic factors have been implicated to play a role in both degenerative lumbar spinal stenosis (LSS) and intervertebral disc disease (IDD). Sequence variations in the genes coding for collagen IX and inflammatory mediators have been indicated as risk factors for IDD.

Nine genes coding for intervertebral disc (IVD) collagens I, II, IX and XI and aggrecan (AGC1) were analyzed for sequence variations in 29 Finnish individuals with LSS. In addition, two polymorphisms in the vitamin D receptor gene and one in the matrix metalloproteinase-3 gene were studied. Study subjects were analyzed both clinically and radiologically. Results indicated an association between the COL11A2 IVS6^-4 a to t polymorphism and LSS (p = 0.0016). Moreover, the t/t genotype was found more often in the patient group compared to controls (p = 0.0011). A novel splicing mutation, likely resulting in the synthesis of a truncated protein, was identified in COL9A2.

Eight hundred four Chinese individuals were screened for the presence of the Trp2 and Trp3 alleles. The Trp2 allele was found in 20% of the individuals compared to the previously reported 5% in Finnish patients with IDD characterized by sciatica. The Trp2 allele was found to predispose to IVD degeneration and end plate herniations, increasing the risk by 2.4-fold from 40 to 49 years of age. In addition, the degeneration was worse in individuals with the Trp2 allele. The risk for annular tears was 4-fold greater in study subjects from 30 to 39 years of age who were Trp2 positive. Surprisingly, the Trp3 allele was absent even though it was found in about 9% of Finnish individuals.

One hundred fifty-five Finnish individuals with IDD characterized by sciatica were analyzed for sequence variations in four genes coding for inflammatory mediators IL1A, IL1B, IL6, and TNFA. In addition, sixteen polymorphisms in inflammatory mediator genes were analyzed. The results identified an association between sciatica and the E5⁺¹⁵T>A polymorphism in IL6 (p = 0.007). A significant association was also seen in the IL6 haplotype analysis (-597 g>a, -572 g>c, -174 g>c and E5⁺¹⁵T>A). The association of the GGGA haplotype with the disease was highly significant (p = 0.0033).