Psoriasis and psoriatic arthritis are the result of a complex interaction of genetic, immunological and environmental factors. The role of genetics is evident by various population-based studies, family-based studies and candidate gene studies both within and outside the major histocompatibility (MHC) region. The PSORS1 gene in the MHC class-l region on chromosome 6 is considered to be the most important gene locus associated with psoriasis. The discovery of the PSORS2 gene 14 years ago paved the way for extensive research in this regard, which led to the identification of various genetic susceptibility factors for psoriasis and psoriatic arthritis. The complex interrelation of immunological changes in psoriasis and other immune-mediated disorders have been studied at a genetic level as well. Novel disease-specific biological pathways have been identified which, in the future, will likely serve as diagnostic or prognostic markers, as well as potential targets of therapy.
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