IL17A and psoriasis: In general, the HLA-Cw6 allele is predictive of type I early-onsetpsoriasis, guttate psoriasis, Koebner phenomenon (KP), susceptibility to the IL23/IL17 axis dysfunction and thus better response to immunotherapies targeting IL17, IL23 and related cytokines, and better response to conventional methotrexate (MTX) therapy.But, the HLA-Cw1 allele is predictive of erythrodermic psoriasis, pustular psoriasis, and axial PsA.