Title : Polymorphisms of the interleukin 6 gene and susceptibility in multiple sclerosis: a systematic and meta-analysis
Multiple sclerosis (MS) is a chronic, degenerative inflammatory disease of the central nervous system characterised by demyelination. Genetic factors have been implicated in its pathogenesis, however their association with MS remains unclear. Genetic variants in the inflammatory mediator, interleukin 6, may determine why some patients are more susceptible to developing the disease while others are not. We undertook a systematic review of single nucleotide polymorphisms (SNPs) in the IL-6 gene to determine their relationship with disease susceptibility.
Methods: We systematically searched Embase, MEDLINE, Cochrane and Google Scholar databases. Studies which investigated SNPs in interleukin-6 and their associations with MS were included. A meta-analysis was conducted in selected variants reported by at least two studies.
Results: Twelve studies which reported on three genetic variants of interleukin 6 gene were studied. One study reported increased risk of MS in patients who carry the G allele for IL-6 572 G/C to statistical significance. Whereas, IL-6 597 G/A was reported to not have any association with disease susceptibility reported by one paper. However, both variants have not been replicated by other studies. IL-6 174 G/C was reported by seven studies respectively and selected for meta-analysis. In our meta-analysis, 2662 cases of MS and 2204 healthy controls were included from seven studies. We estimated a pooled odds ratio of 1.14 (95% CI 1.01-1.29), p<0.03 for the IL-6 174 G/C (C vs G) polymorphism and susceptibility of MS
Conclusion: Our meta-analysis suggests the polymorphism of IL-6 174 G/C are associated with increased susceptibility of MS