Single nucleotide polymorphism in the MMP-9 gene is associated with susceptibility to develop multiple sclerosis in an Italian case-control study.

To investigate the role of the matrix metalloproteinase-9 gene (MMP-9) in multiple sclerosis (MS), we analyzed the functional -1562C/T and -90 (CA)n repeat polymorphisms, located in the promoter region of this gene, in 243 Italian patients with MS and 173 healthy controls. A markedly significant increase of the -1562T allele carriers was found in patients with MS compared to controls (P = 5.6 x 10-5, adjusted OR = 2.57, 95% CI = 1.52- 4.36). Moreover, carriers of (CA)>20 repeats were also significantly more frequent among patients with MS than among controls (P = 0.011, adjusted OR = 1.53, 95% CI = 1.06-2.02). There were no differences in MS disability status, age at onset or disease duration among the genotypes. Haplotype analysis showed that the haplotype formed by the -1562T allele and the L allele ((CA)d20) was over-represented in patients with MS versus controls, suggesting this haplotype could be a possible risk factor for development of the disease (P = 2.14 x 10-5, OR=6.79, 95% CI=2.82-16.35). These results suggest that genetic polymorphisms of the MMP-9 promoter regions may influence the susceptibility to MS.