title: What have we learned about genetic susceptibility in psoriasis and psoriatic arthritis?
abstract: OBJECTIVE
  To review recent evidence for genetic susceptibility in psoriasis and psoriatic arthritis.
  
  
  RESULTS
  Psoriasis and psoriatic arthritis (PsA) have substantive genetic determinants as indicated by their high family aggregation. Psoriasis and PsA share several susceptibility genes; however, other genes, mostly within the major histocompatibility complex (MHC) region, confer an independent risk for PsA. The human leukocyte antigen-C0602 allele confers the highest risk for psoriasis whereas several human leukocyte antigen-B alleles were identified as 'PsA-specific' genes. Fine mapping of the MHC suggests that glutamine at position 45 is an important susceptibility factor for PsA. Additional genes outside of the MHC region were identified as psoriasis susceptibility genes. These genes belong to several proinflammatory pathways and skin barrier mechanisms that play a role in the pathogenesis of psoriatic disease.
  
  
  CONCLUSIONS
  The MHC remains the major susceptibility locus for psoriatic disease. Future studies using next-generation sequencing technologies may reveal novel rare susceptibility genes for this disease.
authors.affiliation: Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, Toronto, Ontario, Canada.
authors.forename: Lihi
authors.initials: L
authors.lastname: Eder
authors.forename: Vinod
authors.initials: V
authors.lastname: Chandran
authors.forename: Dafna D
authors.initials: DD
authors.lastname: Gladman
mesh_terms: D056704:Adaptive Immunity / Q000235:genetics*; D015535:Arthritis, Psoriatic / Q000235:genetics / Q000276:immunology; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D055106:Genome-Wide Association Study; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics*; D011565:Psoriasis / Q000235:genetics* / Q000276:immunology*