Novel IL-6 haplotypes and disease association.

Interleukin-6 (IL-6) is a pleiotropic cytokine crucial in both adaptive and innate immunity. Numerous genetic studies have shown association with variants of this gene in a multitude of diseases and phenotypes. Most tests of association have focused on a limited set of promoter polymorphisms, in particular, the -174G>C; however, there are many inconsistencies within and between these studies. We propose that there is a more complex regulatory haplotype extending further upstream of the previously characterised promoter region which will provide a more detailed view of the effect of variation on lL-6 regulation. We have exploited two additional single nucleotide polymorphisms (SNPs) in IL-6 that, when examined as a haplotype with existing markers, show an increased level of association with systemic onset juvenile arthritis in a family-based study. This suggests that the haplotype effect may be more functionally relevant to the disease.