MEDICAL PHYSIOLOGY AND RHEUMATIC DISEASES: Edited by Jose U. ScherWhat have we learned about genetic susceptibility in psoriasis and psoriatic arthritis?Eder, Lihi; Chandran, Vinod; Gladman, Dafna D. Author Information Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, Toronto, Ontario, Canada Correspondence to Dr Dafna D. Gladman, MD, FRCPC, Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, 399 Bathurst St., 1E-410B, Toronto, ON M5T 2S8, Canada. Tel: +1 416 603 5753; fax: +1 416 603 9387;e-mail: [email protected] Current Opinion in Rheumatology 27(1):p 91-98, January 2015. | DOI: 10.1097/BOR.0000000000000136 Buy Metrics Abstract Purpose of review To review recent evidence for genetic susceptibility in psoriasis and psoriatic arthritis. Recent findings 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-C*0602 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. Summary 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. © 2015 Lippincott Williams & Wilkins, Inc.