At this locus, the most consistently associated allele is the *Cw0602 allele of HLA-C gene, although the remarkably high linkage disequilibrium (LD) at this locus has hampered definite identification of the causative variant.6 In addition, more than nine psoriasis susceptibility loci have been identified (PSORS1-9 and one further for psoriatic arthritis, PSORAS1). Here, HLA-C is linked to psoriatic arthritis.