Other HLA class I alleles associated with a risk of psoriasis are HLA-C*07:01, HLA-C*07:02, HLA-C*07:04, and HLA-B*27:05 [48,49,50,51,52,53], with HLA-B*27:05 and HLA-C*06:02 being phenotype-defining risk alleles also for psoriatic arthritis [48,54]. The gene discussed is HLA-C; the disease is psoriatic arthritis.