HLA-C*06 alleles are the genetic component for the predisposition to the autoimmune reactions that result in psoriasis. Recent total-genome association studies have confirmed that of all gene sites HLA-C shows the highest association with psoriasis, and HLA-C*06 can be considered as by far the most powerful genetic marker for the disease. In chronic inflammatory skin diseases the determination of HLA-C*06 is of great significance for differential diagnostics, since the presence of the HLA-Cw6 antigen is associated in particular with type 1 psoriasis vulgaris (OR 16.0) and psoriasis guttata (OR 33.6), but only is comparatively weakly associated (OR 2.6) with type 2 psoriasis vulgaris. In type 1 psoriasis vulgaris around 83% of patients carry the HLA-C*06 allele, whereas in type 2 the proportion of HLA-Cw6-positive patients is only 44%. Type 1 psoriasis vulgaris has a more severe course than type 2 psoriasis vulgaris.
The EUROArray HLA-Cw6 Direct has been specifically designed for the determination of HLA-C*06 alleles. It is therefore particularly easy to perform compared to other molecular biological methods for the detection of HLA-C*06. In this test system the PCR primers have been chosen and optimised so that all relevant HLA-C*06 subtypes are detected.