Exome-wide association study reveals novel psoriasis susceptibility locus at TNFSF15 and rare protective alleles in genes contributing to type I IFN signalling.

Nick Dand, Sören Mucha, Lam C Tsoi, Satveer K Mahil, Philip E Stuart, Andreas Arnold, Hansjörg Baurecht, A David Burden, Kristina Callis Duffin, Vinod Chandran, Charles J Curtis, Sayantan Das, David Ellinghaus, Eva Ellinghaus, Charlotta Enerback, Tõnu Esko, Dafna D Gladman, Christopher E M Griffiths, Johann E Gudjonsson, Per Hoffman, Georg Homuth, Ulrike Hüffmeier, Gerald G Krueger, Matthias Laudes, Sang Hyuck Lee, Wolfgang Lieb, Henry W Lim, Sabine Löhr, Ulrich Mrowietz, Martina Müller-Nurayid, Markus Nöthen, Annette Peters, Proton Rahman, André Reis, Nick J Reynolds, Elke Rodriguez, Carsten O Schmidt, Sarah L Spain, Konstantin Strauch, Trilokraj Tejasvi, John J Voorhees, Richard B Warren, Michael Weichenthal, Stephan Weidinger, Matthew Zawistowski, Rajan P Nair, Francesca Capon, Catherine H Smith, Richard C Trembath, Goncalo R Abecasis, James T Elder, Andre Franke, Michael A Simpson, Jonathan N Barker
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Human molecular genetics
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Psoriasis is a common inflammatory skin disorder for which multiple genetic susceptibility loci have been identified, but few resolved to specific functional variants. In this study we sought to identify common and rare psoriasis-associated gene-centric variation. Using exome arrays we genotyped four independent cohorts, totalling 11,861 psoriasis cases and 28,610 controls, aggregating the dataset through statistical meta-analysis. Single variant analysis detected a previously unreported risk locus at TNFSF15 (rs6478108; p = 1.50 × 10-8, OR = 1.10), and association of common protein-altering variants at 11 loci previously implicated in psoriasis susceptibility. We validate previous reports of protective low-frequency protein-altering variants within IFIH1 (encoding an innate antiviral receptor) and TYK2 (encoding a Janus kinase), in each case establishing a further series of protective rare variants (minor allele frequency < 0.01) via gene-wide aggregation testing (IFIH1: pburden = 2.53 × 10-7, OR = 0.707; TYK2: pburden = 6.17 × 10-4, OR = 0.744). Both genes play significant roles in type I interferon (IFN) production and signalling. Several of the protective rare and low-frequency variants in IFIH1 and TYK2 disrupt conserved protein domains, highlighting potential mechanisms through which their effect may be exerted.