Fine mapping of multiple sclerosis susceptibility genes provides evidence of allelic heterogeneity at the IL2RA locus

Multiple sclerosis (MS) is a genetically complex autoimmune disease. To dissect further the involvement of four recent identified MS susceptibility genes (KIAA0350, IL2RA, RPL5 and CD58) in disease pathogenesis, we genotyped 94 haplotype-tagging single nucleotide polymorphisms (SNPs) from these loci in 1146 MS cases and 1309 controls. Seven newly-typed SNP variants were nominally associated with risk of MS, and one SNP (rs791589) in the first intron of the IL2RA gene remained associated after adjustment for rs2104286 genotype, a previously reported SNP association. These data provide further evidence of allelic heterogeneity at the IL2RA locus and point to the existence of at least two independent MS susceptibility alleles.