Besides the HLA loci: SNPs and non-HLA gene products as immunoregulatory factors in the onset of psoriatic arthritis subtypes.

Psoriatic arthritis (PsA) is described as a multifactorial autoimmune rheumatic disease although its development is surely linked to some specific HLA genes (especially the HLA-Cw*06:02 allele). To date, its complex immunopathogenetic mechanism is not well clarified. Actually, increasing evidence suggest that qualitative and quantitative interplays between some PsA-susceptibility HLA alleles and other genetic, regulatory and environmental factors, may develop distinct subphenotypes of PsA. We first provide a brief summary of current knowledge about the various PsA conditions. Then, we consider the reasons why further analysis of the clinical course of patients affected by distinct PsA subsets, and who receive different therapeutic treatments, should be carried out in conjunction with deeper investigations about the identification of key genes and immunoregulatory agents by applying the most recent advances in biotechnology. This approach could better explain the molecular mechanisms responsible for both the onset and progression of this multi-faceted pathology with the purpose of significantly improving the management of PsA patients.