More than 40 regions in the human genome have been associated with psoriasis [14], such as HLA-Cw6, IL12B, IL23R, LCE3A, LCE3D, and STAT3C. The chromosomal region that is thought to encode a psoriasis gene is referred to as the psoriasis susceptibility (PSORS) locus and is currently known to encode at least 15 different PSORS loci, which are mainly linked by a chain analysis of multiple members of the psoriasis family. This evidence concerns the gene IL12B and psoriasis.