HLA-C and multiple sclerosis: Recently, the presence of the activating KIR2DS1 and KIR2DS2 genes was reported to be a novel risk factor for psoriasis and an interaction between HLA-C and KIR observed with the overall combination of activating and inhibitory genotypes influencing susceptibility.56 Association of combinations between HLA class I and KIR genes has also been reported for a range of other infectious and autoimmune diseases.54 This provides a strong rationale for investigating the KIR gene cluster as a candidate susceptibility locus in multiple sclerosis subsequent to our finding of association with HLA-C.