Key elements of psoriasis immunogenetics: A review

Psoriasis is one of the most common skin diseases, affecting 2% to 3% of the world population. It occurs at any stage of life. "Early" psoriasis or type I manifests before 40 years, and "late" psoriasis or type II, after 40 years. It has a strong genetic basis and the probability of inheriting the disease when both parents are affected is up to 50%. Different susceptibility regions associated with psoriasis, called PSORS, have been described, PSORS-1 being the most frequent one. It is in chromosome 6 and in this region HLA-Cw6 is located, which is until now the gene more associated with psoriasis. The role of HLA-Cw6 in psoriasis is not fully understood, but it has a relationship with type I psoriasis, guttate psoriasis and the presentation of an array of antigens including those derived from Streptococcus pyogenes. Furthermore, some single nucleotide polymorphisms in genes encoding cytokines such as IL-12, IL-23, TNF-alpha or their receptors are associated with the immunopathogenesis of the disease.