A systemic sclerosis and systemic lupus erythematosus pan ... gwas ssc sle.pdfand Ine´s Vaqueiro,...

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A systemic sclerosis and systemic lupus erythematosus pan-meta-GWAS reveals new shared susceptibility loci Jose-Ezequiel Martin 1, { , , Shervin Assassi 2, { , Lina-Marcela Diaz-Gallo 1 , Jasper C. Broen 3,4 , Carmen P. Simeon 5 , Ivan Castellvi 6 , Esther Vicente-Rabaneda 7 , Vicente Fonollosa 5 , Norberto Ortego-Centeno 8 , Miguel A. Gonza ´lez-Gay 9 , Gerard Espinosa 10 , Patricia Carreira 11 , Spanish Scleroderma Group { , SLEGEN consortium § , U.S. Scleroderma GWAS group ∗∗ , BIOLUPUS {{ , Mayte Camps 12 , Jose M. Sabio 13 , Sandra D’alfonso 14 , Madelon C. Vonk 3 , Alexandre E. Voskuyl 15 , Annemie J. Schuerwegh 16 , Alexander Kreuter 17 , Torsten Witte 18 , Gabriella Riemekasten 19 , Nicolas Hunzelmann 20 , Paolo Airo 21 , Lorenzo Beretta 22 , Raffaella Scorza 22 , Claudio Lunardi 23 , Jacob Van Laar 24 , Meng May Chee 25 , Jane Worthington 26 , Arianne Herrick 26 , Christopher Denton 27 , Carmen Fonseca 27 , Filemon K. Tan 2 , Frank Arnett 2 , Xiaodong Zhou 2 , John D. Reveille 2 , Olga Gorlova 28 , Bobby P.C. Koeleman 29 , Timothy R.D.J. Radstake 4, { , Timothy Vyse 30, { , Maureen D. Mayes 2, { , Marta E. Alarco ´ n-Riquelme 31, { and Javier Martin 1, { 1 Instituto de Parasitologia y Biomedicina Lopez-Neyra, CSIC, Granada, Spain, 2 The University of Texas Health Science Center – Houston, Houston, TX, USA, 3 Department of Rheumatology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands, 4 Department of Rheumatology, Clinical Immunology and Translational Immunology, # The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected] These authors contributed equally to this work. To whom correspondence should be addressed. Email: [email protected] The Spanish Scleroderma Group members are: Rosa Garcı ´a Portales, Hospital Virgen de la Victoria, Ma ´laga. Enrique de Ramon and Antonio Ferna ´ndez- Nebro, Hospital Carlos Haya, Ma ´laga. Jose Roma ´n-Ivorra and Emma Beltran, Hospital Dr. Peset, Valencia. Mª Jesu ´ s Castillo and Julio Sa ´nchez-Roma ´n, Hospital Virgen del Rocı ´o, Sevilla. Esther Vicente, Hospital La Princesa, Madrid. Bernardino Dı ´az, Luis Trapiella and Marı ´a Gallego, Hospital Central de Asturias, Oviedo. Mª A ´ ngeles Aguirre, Hospital Reina Sofı ´a, Co ´ rdoba. Jose Luis Callejas-Rubio and Raquel Rı ´os, Hospital San Cecilio, Granada. Iva ´n Cas- tellvi, Hospital Sant Pau, Barcelona. Mª Victoria Egurbide, Hospital de Cruces, Vizcaya. Gerard Espinosa, Hospital Clinic, Barcelona. Anna Pros, Hospital del Mar, Barcelona. Nuria Navarrete, Hospital Virgen de las Nieves, Granada. Federico Dı ´az-Gonza ´lez and Vanesa Herna ´ndez, Hospital Universitario de Canarias, Tenerife. Jose ´ Luis Andre ´u and Mo ´nica Ferna ´ndez-Castro, Hospital Puerta del Hierro, Madrid. Luis Sa ´ez Comet, Hospital Miguel Servet, Zara- goza. Francisco J. Lo ´ pez-Longo and Lina Martinez-Estupin ˜ an, Hospital Gregorio Maran ˜o ´ n, Madrid. Mo ´nica Rodrı ´guez-Carballeira, Hospital Universitari Mu ´ tua Terrassa, Barcelona. Francisco Javier Narva ´ez, Servicio de Reumatologı ´a, Hospital Universitari de Bellvitge, Barcelona Marı ´a del Carmen Freire and Ine ´s Vaqueiro, Hospital Xeral-Complexo Hospitalario, Vigo. § The SLEGEN Consortium members are: Marta E. Alarco ´ n-Riquelme (Oklahoma Medical Research Foundation and Centro de Geno ´ mica e Investigacio ´n Oncolo ´ gica Pfizer-Universidad de Granada-Junta de Andalucı ´a), Lindsey A. Criswell (University of California, San Francisco), John B. Harley (Cincinnati Children’s Hospital Medical Center), Chaim O. Jacob (University of Southern California), Robert P. Kimberly (University of Alabama at Birmingham), Carl D. Langefeld (Wake Forest University Health Sciences), Kathy L. Moser (Oklahoma Medical Research Foundation), Betty P. Tsao (University of California, Los Angeles), and Timothy J. Vyse (King’s College London). ∗∗ The United States Scleroderma GWAS Group members are: Jun Ying (Department of Epidemiology, M.D. Anderson Cancer Center, Houston, TX, USA), John Varga, Monique Hinchcliff (Northwestern University Feinberg School of Medicine, Chicago, IL USA), Peter Gregersen, Annette T. Lee (Feinstein Institute of Medical Research, Manhasset, NY, USA), Fredrick M. Wigley, Laura Hummers (Johns Hopkins University Medical Center, Baltimore, MD, USA). †† The following samples were obtained in via the BIOLUPUS network coordinated by Marta Alarco ´n-Riquelme (GENYO, OMRF) Belgium: Bernard Lawerys and Fredric Houssiau (Universite ´ Catholique de Louvain) Denmark: Søren Jacobsen (University of Copenhagen), Peter Junker, Helle Laustrup (Odense University Hospital). Germany: Torsten Witte (Medizinische Hochschule Hannover). Greece: Haralampos Moutsopoulos, Etstathia K Kapsogeor- gou (National University of Athens). Hungary: Emo ´´ke Endreffy and Laszlo Kovacs (Albert Szent-Gyo ¨ rgyi Medical University). Iceland: Kristja ´n Steinsson (Landspitali National University Hospital). Italy: Andrea Doria (University of Padova), Pier Luigi Meroni (IRCCS Istituto Auxologico Italiano), Rafaella Scorza (University of Milan), Sandra D’Alfonso (providing samples from Rome, Naples and Siena, Universita ` del Piemonte Orientale). Netherlands: Marc Bijl, Cees Kallenberg (University of Groningen). Portugal: Carlos Vasconcelos (Hospital Santo Anto ´ nio, Porto), Berta Martins Silva (University of Porto). Spain: Javier Martı ´n, Jose-Ezequiel Martı ´n (Instituto de Parasitologı ´a y Biomedicina “Lopez-Neyra”), Ana Sua ´rez (Hospital Universitario Central de As- turias), In ˜ igo Rua Figueroa (Hospital Dr Negrı ´n, Gran Canaria), Guillermo Pons-Estel (Hospital Clinic, Barcelona). Sweden: Johan Frostega ˚rd (Karolinska Institutet). From the GENLES collaboration: Argentina: Bernardo Pons-Estel (Hospital Provincial de Rosario). Human Molecular Genetics, 2013 1–9 doi:10.1093/hmg/ddt248 HMG Advance Access published June 10, 2013 at HAM-TMC Library on August 13, 2013 http://hmg.oxfordjournals.org/ Downloaded from

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  • A systemic sclerosis and systemic lupuserythematosus pan-meta-GWAS reveals newshared susceptibility loci

    Jose-Ezequiel Martin1,{,∗, Shervin Assassi2,{, Lina-Marcela Diaz-Gallo1, Jasper C. Broen3,4,

    Carmen P. Simeon5, Ivan Castellvi6, Esther Vicente-Rabaneda7, Vicente Fonollosa5,

    Norberto Ortego-Centeno8, Miguel A. González-Gay9, Gerard Espinosa10, Patricia Carreira11,

    Spanish Scleroderma Group{, SLEGEN consortium§, U.S. Scleroderma GWAS group∗∗,

    BIOLUPUS{{, Mayte Camps12, Jose M. Sabio13, Sandra D’alfonso14, Madelon C. Vonk3,

    Alexandre E. Voskuyl15, Annemie J. Schuerwegh16, Alexander Kreuter17, Torsten Witte18,

    Gabriella Riemekasten19, Nicolas Hunzelmann20, Paolo Airo21, Lorenzo Beretta22,

    Raffaella Scorza22, Claudio Lunardi23, Jacob Van Laar24, Meng May Chee25, Jane Worthington26,

    Arianne Herrick26, Christopher Denton27, Carmen Fonseca27, Filemon K. Tan2, Frank Arnett2,

    Xiaodong Zhou2, John D. Reveille2, Olga Gorlova28, Bobby P.C. Koeleman29,

    Timothy R.D.J. Radstake4,{, Timothy Vyse30,{, Maureen D. Mayes2,{, Marta E. Alarcón-Riquelme31,{

    and Javier Martin1,{

    1Instituto de Parasitologia y Biomedicina Lopez-Neyra, CSIC, Granada, Spain, 2The University of Texas Health Science

    Center–Houston, Houston, TX, USA, 3Department of Rheumatology, Radboud University Nijmegen Medical Center,

    Nijmegen, The Netherlands, 4Department of Rheumatology, Clinical Immunology and Translational Immunology,

    # The Author 2013. Published by Oxford University Press. All rights reserved.For Permissions, please email: [email protected]

    †These authors contributed equally to this work.

    ∗To whom correspondence should be addressed. Email: [email protected]

    ‡The Spanish Scleroderma Group members are: Rosa Garcı́a Portales, Hospital Virgen de la Victoria, Málaga. Enrique de Ramon and Antonio Fernández-Nebro, Hospital Carlos Haya, Málaga. Jose Román-Ivorra and Emma Beltran, Hospital Dr. Peset, Valencia. Mª Jesús Castillo and Julio Sánchez-Román,Hospital Virgen del Rocı́o, Sevilla. Esther Vicente, Hospital La Princesa, Madrid. Bernardino Dı́az, Luis Trapiella and Marı́a Gallego, Hospital Central deAsturias, Oviedo. Mª Ángeles Aguirre, Hospital Reina Sofı́a, Córdoba. Jose Luis Callejas-Rubio and Raquel Rı́os, Hospital San Cecilio, Granada. Iván Cas-tellvi, Hospital Sant Pau, Barcelona. Mª Victoria Egurbide, Hospital de Cruces, Vizcaya. Gerard Espinosa, Hospital Clinic, Barcelona. Anna Pros, Hospitaldel Mar, Barcelona. Nuria Navarrete, Hospital Virgen de las Nieves, Granada. Federico Dı́az-González and Vanesa Hernández, Hospital Universitario deCanarias, Tenerife. José Luis Andréu and Mónica Fernández-Castro, Hospital Puerta del Hierro, Madrid. Luis Sáez Comet, Hospital Miguel Servet, Zara-goza. Francisco J. López-Longo and Lina Martinez-Estupiñan, Hospital Gregorio Marañón, Madrid. Mónica Rodrı́guez-Carballeira, Hospital UniversitariMútua Terrassa, Barcelona. Francisco Javier Narváez, Servicio de Reumatologı́a, Hospital Universitari de Bellvitge, Barcelona Marı́a del Carmen Freireand Inés Vaqueiro, Hospital Xeral-Complexo Hospitalario, Vigo.§The SLEGEN Consortium members are: Marta E. Alarcón-Riquelme (Oklahoma Medical Research Foundation and Centro de Genómica e InvestigaciónOncológica Pfizer-Universidad de Granada-Junta de Andalucı́a), Lindsey A. Criswell (University of California, San Francisco), John B. Harley (CincinnatiChildren’s Hospital Medical Center), Chaim O. Jacob (University of Southern California), Robert P. Kimberly (University of Alabama at Birmingham),Carl D. Langefeld (Wake Forest University Health Sciences), Kathy L. Moser (Oklahoma Medical Research Foundation), Betty P. Tsao (University ofCalifornia, Los Angeles), and Timothy J. Vyse (King’s College London).∗∗The United States Scleroderma GWAS Group members are: Jun Ying (Department of Epidemiology, M.D. Anderson Cancer Center, Houston, TX, USA),John Varga, Monique Hinchcliff (Northwestern University Feinberg School of Medicine, Chicago, IL USA), Peter Gregersen, Annette T. Lee (FeinsteinInstitute of Medical Research, Manhasset, NY, USA), Fredrick M. Wigley, Laura Hummers (Johns Hopkins University Medical Center, Baltimore, MD,USA).††The following samples were obtained in via the BIOLUPUS network coordinated by Marta Alarcón-Riquelme (GENYO, OMRF) Belgium: BernardLawerys and Fredric Houssiau (Université Catholique de Louvain) Denmark: Søren Jacobsen (University of Copenhagen), Peter Junker, Helle Laustrup(Odense University Hospital). Germany: Torsten Witte (Medizinische Hochschule Hannover). Greece: Haralampos Moutsopoulos, Etstathia K Kapsogeor-gou (National University of Athens). Hungary: Emó́ke Endreffy and Laszlo Kovacs (Albert Szent-Györgyi Medical University). Iceland: Kristján Steinsson(Landspitali National University Hospital). Italy: Andrea Doria (University of Padova), Pier Luigi Meroni (IRCCS Istituto Auxologico Italiano), RafaellaScorza (University of Milan), Sandra D’Alfonso (providing samples from Rome, Naples and Siena, Università del Piemonte Orientale). Netherlands: MarcBijl, Cees Kallenberg (University of Groningen). Portugal: Carlos Vasconcelos (Hospital Santo António, Porto), Berta Martins Silva (University of Porto).Spain: Javier Martı́n, Jose-Ezequiel Martı́n (Instituto de Parasitologı́a y Biomedicina “Lopez-Neyra”), Ana Suárez (Hospital Universitario Central de As-turias), Iñigo Rua Figueroa (Hospital Dr Negrı́n, Gran Canaria), Guillermo Pons-Estel (Hospital Clinic, Barcelona). Sweden: Johan Frostegård (KarolinskaInstitutet). From the GENLES collaboration: Argentina: Bernardo Pons-Estel (Hospital Provincial de Rosario).

    Human Molecular Genetics, 2013 1–9doi:10.1093/hmg/ddt248

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  • University Utrecht Medical Center, Utrecht, The Netherlands, 5Servicio de Medicina Interna, Hospital Valle de Hebron,

    Barcelona, Spain, 6Servicio de Reumatologı́a, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain, 7Servicio de

    Reumatologı́a, Hospital La Princesa, Madrid, Spain, 8Servicio de Medicina Interna, Hospital Clı́nico Universitario,

    Granada,Spain, 9ServiciodeReumatologı́a,HospitalMarquésdeValdecilla, IFIMAV,Santander,Spain, 10Departmentof

    Systemic Autoimmune Diseases, Hospital Clinic de Barcelona, Barcelona, Spain, 11Hospital 12 de Octubre, Madrid,

    Spain, 12Servicio de Medicina Interna, Hospital Carlos Haya, Málaga, Spain, 13Unidad de Enfermedades Autoinmunes

    Sistémicas, Servicio de Medicina Interna, Hospital Universitario Virgen de las Nieves, Granada, Spain, 14Department of

    Medical Sciences and Institute of Research in Chronic Autoimmune Diseases (IRCAD), University of Eastern Piedmont,

    Novara, Italy, 15VU UniversityMedical Center,Amsterdam, The Netherlands, 16Department ofRheumatology, University of

    Leiden, Leiden, The Netherlands, 17Department of Dermatology, Josefs-Hospital, Ruhr University Bochum, Bochum,

    Germany, 18Hannover Medical School, Hannover, Germany, 19Department of Rheumatology and Clinical Immunology,

    Charité University Hospital, Berlin, Germany, 20Department of Dermatology, University of Cologne, Cologne, Germany,21Rheumatology Unitand Chair, Spedali Civili, Università de GliStudi, Brescia, Italy, 22Referral Center for Systemic

    Autoimmune Diseases, Fondazione IRCCS Ca’Granda Ospedale Ma Repiore Policlinico and University of Milan, Milan,

    Italy, 23Department of Medicine, Policlinico GB Rossi, University of Verona, Verona, Italy, 24Institute of Cellular Medicine,

    Newcastle University, Newcastle Upon Tyne, UK, 25Centre for Rheumatic Diseases, Glasgow Royal Infirmary Glasgow,

    Glasgow, UK, 26Department of Rheumatology and Epidemiology, University of Manchester, Manchester Academic Health

    Science Centre, Manchester, UK, 27Centre for Rheumatology, Royal Free and University College School, London,28Department of Epidemiology, MD Anderson Cancer Center, Houston, TX, USA, 29Department of Medical Genetics,

    UniversityMedicalCenterUtrecht,Utrecht,TheNetherlands,30DivisionsofGeneticsandMolecularMedicineandDivisionof

    Immunology, Infection and Inflammatory Disease, King’s College London, Guy’s Hospital, London, UK and 31Centro de

    Genómica e Investigación Oncológica (GENYO) Pfizer-Universidad de Granada-Junta de Andalucı́a, Granada, Spain

    Received March 22, 2013; Revised and Accepted May 28, 2013

    Systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are two archetypal systemic autoimmunediseases which have been shown to share multiple genetic susceptibility loci. In order to gain insight into thegenetic basis of these diseases, we performed a pan-meta-analysis of two genome-wide association studies(GWASs) together with a replication stage including additional SSc and SLE cohorts. This increased thesample size to a total of 21 109 (6835 cases and 14 274 controls). We selected for replication 19 SNPs from theGWAS data. We were able to validate KIAA0319L (P 5 3.31 3 10211, OR 5 1.49) as novel susceptibility loci forSSc and SLE. Furthermore, we also determined that the previously described SLE susceptibility loci PXK(P 5 3.27 3 10211, OR 5 1.20) and JAZF1 (P 5 1.11 3 1028, OR 5 1.13) are shared with SSc. Supporting thesenew discoveries, we observed that KIAA0319L was overexpressed in peripheral blood cells of SSc and SLEpatients compared with healthy controls. With these, we add three (KIAA0319L, PXK and JAZF1) and one(KIAA0319L) new susceptibility loci for SSc and SLE, respectively, increasing significantly the knowledge ofthe genetic basis of autoimmunity.

    INTRODUCTION

    Most autoimmune disorders are genetically complex and clinic-ally heterogeneous. Classification permits physicians to distin-guish individual autoimmune criteria based on the typicalclinical features. However, underlying these separate clinicalfeatures, there is a genetic continuum of susceptibility factorsand molecular pathways leading to autoimmunity. Thisbecomes clear when analyzing existing genetic data accordingto clinical subphenotypes, reducing the overall genetic hetero-geneity in the analyses (1–8). This has been clearly demon-strated in rheumatoid arthritis (RA), in which separatinganti-citrullinated protein antibody positive and negative casesresulted in a far more homogeneous genetic analysis revealing

    genetic subgroups (1,3–6). The aim of personalized medicineis thus to accomplish a degree of resolution that allows us to dis-tinguish genetically and molecularly such groups and providemore targeted therapeutic interventions.

    There is a growing body of evidence that all autoimmune dis-orders share to a varying degree their genetic susceptibility loci(9). It is clear that lack of statistical power due to limited samplesize is a barrier to completely defining the genetic contribution toautoimmunity. As we increase our sample size, we can identifyadditional genes shared by some diseases but not shared byothers. From the viewpoint that all autoimmune disorders areheterogeneous entities whose specific manifestations dependon the presence of several susceptibility genetic variants and

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  • environmental triggers, the combined analysis of different auto-immune disorders will greatly increase our statistical power todetect modest genetic effects shared among them. This approachhas already been successfully used to detect the shared geneticsusceptibility component of RA, celiac disease, psoriasis andCrohn’s disease (10–12). In the present study, we meta-analyzethe GWASs of two autoimmune disorders that have been demon-strated to share a relatively large portion of their genetic compo-nent and clinical features: systemic sclerosis (SSc) and systemiclupus erythematosus (SLE) (13, 14), identifying new loci foreach disease. We would suggest a similar approach for otherautoimmune diseases in the future.

    RESULTS

    The overall process followed during this study is illustrated inFigure 1 and described in detail in the Materials and methodssection. Briefly, from the pan-meta-analysis of the SSc andSLE GWAS (15,16), we selected all SNPs which presented aGC-corrected P-value of ,5 × 1026. From these, we furtherselected for replication all SNPs which were associated withboth diseases independently at nominal level. For a moredetailed description of the selection criteria, see the Materialsand methods section.

    According to these selection criteria, we investigated 19 SNPswhose statistics are shown in Table 1 and Figure 2. According tothe significance criteria established (see Materials and methodssection), we could confirm one new association shared by SSc(more specifically in the limited cutaneous subtype) and SLE:rs2275247 in KIAA0319L (combined P-value ¼ 1.40 × 10210,OR¼ 1.51; SSc P-value ¼ 3.92 × 1026; SLE P-value¼ 4.44 ×1026) (Table 1). Furthermore, we were able to determine twonew genetic susceptibility regions at genome-wide level of signifi-cance in the combined analysis of SSc which had been previouslydescribed only in SLE: PXK (rs2176082, combined P-value¼5.24 × 10211, OR¼ 1.21; SSc P-value¼ 4.44 × 1027; SLEP-value¼ 1.12 × 1025) and JAZF1 (combined P-value¼1.60 × 1028, OR¼ 1.14; SSc P-value¼ 3.63 × 1025; SLEP-value¼ 1.19 × 1024) but with a modest association particularly

    for the SSc analysis alone. This suggests a minor role of thesegenetic variants in SSc compared with SLE (Table 1). It is note-worthy that the associations present in the KIAA0319L and PXKregions were still significant at GWAS level after including as cov-ariates the first three principal components in a logistic regressionmodel, while the association in the JAZF1 was slightly reducedbelow GWAS level after this (the P-value not corrected for princi-pal components was 1.60 × 1028 and after principal componentcorrection was 5.52 × 1028), which suggests minor populationstratification for this SNP (Table 1).

    In whole blood gene expression data, we observed thatKIAA0319L was significantly overexpressed in SLE patientscompared with unaffected controls [P ¼ 5.36 × 1025, false dis-covery rate (FDR) ¼ 2.94 × 1023] with a fold change of 1.9,while in SSc, there was a trend towards overexpression com-pared with healthy individuals (P ¼ 9.05 × 1023, FDR ¼0.14) with a fold change of 1.3. No significant expression differ-ences were observed for PXK and JAZF1 in either SSc or SLEcompared with controls (Table 2).

    Finally, we wanted to address how the biological processes aredifferentially distributed and shared between SSc and SLE. Forthis, we assigned each SNP with a P-value of ,0.05 and 5 ×1026 to a gene (allowing a 20 kb window surrounding it). Withthis we were able to determine whether any particular biologicalprocess was overrepresented among these two sets of GWAS as-sociation (P , 0.05 and P , 5 × 1026). As observed in Table 3,the biological processes most significantly overrepresentedamong the SSc and SLE associated genes were those belongingto the immune system (27 processes for SSc, being the bestP-value ¼ 2.05 × 10213; and 8 processes for SLE being thebest P ¼ 2.14 × 1028). Among these immune system processesinvolved in SSc and SLE, the topmost one was cellular responseto interferon-gamma (GO term 0071346). Another set of pro-cesses apparently shared by SSc and SLE were those related tothe nervous system, while signaling, molting and cell adhesionwere exclusively overrepresented among the SSc associatedgenes (Table 3).

    DISCUSSION

    Utilizing a GWAS pan-meta-analysis strategy, we were able toidentify a total of three new autoimmunity susceptibility loci,all of which are new for SSc and one of which is new for SLE.These new genetic susceptibility loci were undetected in the pre-vious SSc and SLE GWASs due to the lack of statistical power.

    Theclearest example of this is rs2275247 in KIAA0319L, with aminor allele frequency of 3.43% in our GWAS cohorts, whichwould have gone undetected as Supplementary Material,Table S1, predicts. However, due to the combined analysis, wewere able to capture this association in our meta-analysis.KIAA0319L was previously associated with learning and cogni-tion disabilities (17). Interestingly, the protein contains amongits evolutionary conserved domains a polycystic kidney diseasedomain, which is an immunoglobulin family-like domain ofunclear function (18). Furthermore, KIAA0319L was significantlyoverexpressed in peripheral blood cells from SLE patients com-pared with those of healthy controls, also showed that a similartrend was observed in SSc (Table 2). Another possible lead point-ing to the role of KIAA0319L in autoimmunity can be found in

    Figure 1. Workflow diagram showing the overall process followed during thepresent work.

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  • Table 1. Results of the GWAS analysis, replication analysis and combined analysis of the 19 SNPs selected for replication under different criteria (see Materials and methods)

    Chr. SNP Change Locus SScGroupa

    Combined GWAS ReplicationCombined SSc SLE Combined SSc SLE Combined SSc SLEPb Pc OR Pb OR Pb OR Pb OR Pb OR Pb OR Pb OR Pb OR Pb OR

    1 rs2275247 C/T KIAA0319L lcSSc 1.40E210 4.34E210 1.51 3.92E206 1.46 4.44E206 1.58 7.62E207 1.53 1.22E204 1.47 9.76E204 1.71 3.28E205 1.49 1.06E202 1.46 9.17E204 1.522 rs4907310 T/C ITPRIPL1 dcSSc 7.73E204 2.65E204 1.10 2.99E203 1.15 4.89E202 0.93 1.24E207 1.25 3.81E204 1.22 7.62E205 0.79 5.90E201 0.98 9.65E201 1.00 5.63E201 1.032 rs12466487 C/T R3HDM1 dcSSc 3.73E202 9.58E201 1.08 1.76E204 1.24 6.86E201 1.02 5.42E208 1.32 7.78E204 1.25 7.92E206 0.71 2.78E203 0.85 8.98E202 1.20 9.83E206 1.312 rs10498070 C/A DNPEP lcSSc 1.87E207 8.92E206 1.16 1.44E202 1.10 6.98E207 0.81 5.37E207 1.23 7.27E203 1.14 5.74E207 0.70 2.46E202 1.10 6.39E201 1.03 1.40E202 0.883 rs2176082 A/G PXK ACA 5.24E211 1.68E209 1.21 4.44E207 1.27 1.12E205 1.18 1.16E208 1.27 6.09 E206 1.30 4.11E204 1.24 2.79E204 1.16 1.74E202 1.21 4.76E203 1.154 rs6814708 C/T SORCS2 ACA 1.81E205 9.01E204 0.89 6.80E204 0.86 5.26E203 1.10 1.29E207 0.81 3.13E203 0.85 5.53E206 1.30 3.65E201 0.97 8.56E202 0.88 9.87E201 1.005 rs285912 G/C KCNN2 ACA 1.52E205 9.93E204 0.88 1.33E204 0.83 1.19E202 1.10 1.49E207 0.80 7.10E204 0.82 5.10E205 1.28 3.30E201 0.96 6.62E202 0.86 9.52E201 1.006 rs2145748 A/G CDC5L lcSSc 6.50E203 5.85E203 0.92 2.27E202 0.91 1.13E201 1.07 4.52E207 0.82 6.82E204 0.84 1.30E204 1.28 2.27E201 1.05 4.28E201 1.06 3.62E201 0.966 rs3827644 C/G ATG5 SSc 4.95E207 1.86E206 1.15 4.16E203 1.12 1.28E205 1.21 7.72E207 1.20 5.51E203 1.13 1.73E206 1.38 4.61E202 1.09 3.37E201 1.07 7.62E202 1.107 rs4725072 A/C ICA1 SSc 1.55E205 6.04E205 1.22 1.85E203 1.22 2.49E203 1.24 2.78E205 1.31 2.25E203 1.27 2.88E203 1.41 5.65E202 1.14 2.74E201 1.12 1.13E201 1.157 rs1635852 T/C JAZF1 SSc 1.60E208 5.52E208 1.14 3.63E205 1.13 1.19E204 1.14 2.08E205 0.88 1.71E203 0.89 2.73E203 1.18 2.27E204 1.13 6.52E203 1.15 1.10E202 1.127 rs1133906 T/C SAMD9L lcSSc 2.27E207 2.96E206 1.21 2.81E203 1.17 1.41E205 1.25 7.43E208 1.31 5.23E204 1.25 1.54E205 1.43 4.75E202 1.11 7.70E201 1.03 2.60E202 1.159 rs1002841 C/T SEC61B ACA 9.76E203 1.98E202 1.08 9.99E202 1.08 4.62E202 0.93 2.45E207 1.24 8.97E203 1.16 1.53E206 0.74 1.56E201 0.95 4.58E201 0.95 2.29E201 1.069 rs7038399 A/G AKAP2 dcSSc 1.72E204 2.49E203 0.83 1.80E203 0.77 1.70E202 0.86 3.81E208 0.65 1.15E204 0.66 6.51E205 0.64 8.47E201 1.01 8.04E201 1.04 9.25E201 1.0110 rs10903528 A/G ADARB2 ATA 1.63E205 7.09E204 1.22 3.91E204 1.32 5.47E203 0.85 5.35E207 1.40 3.89E205 1.48 2.61E203 0.75 2.21E201 1.08 6.87E201 1.06 2.44E201 0.9211 rs1355223 A/G EHF lcSSc 3.72E206 3.26E205 1.12 8.91E205 1.15 8.70E203 1.10 3.87E207 1.19 2.42E204 1.17 3.88E204 1.22 1.51E201 1.05 1.05E201 1.10 5.52E201 1.0312 rs10161149 T/C NAV3 dcSSc 2.11E204 7.41E205 1.24 2.87E203 1.31 1.78E202 1.19 3.05E207 1.51 1.29E202 1.30 4.17E207 1.86 6.38E201 1.04 9.98E202 1.32 7.21E201 0.9715 rs2925256 T/C UBE3A ATA 6.62E203 7.00E203 1.29 1.39E202 1.45 1.05E201 1.21 9.90E207 1.88 1.98E205 2.12 6.11E203 1.65 6.06E201 0.93 1.37E201 0.63 9.28E201 1.0115 rs9920771 T/C NEO1 ATA 1.09E204 1.28E204 0.75 1.99E202 0.70 1.45E203 1.31 4.28E209 0.49 3.47E203 0.54 1.49E207 2.12 6.07E201 0.95 9.95E201 1.00 5.67E201 1.06

    The loci associated at GWAS level in the pan-meta-analysis are marked in bold.aAll SSc and SSc-SLE combined P-values are referred to the specified SSc phenotype.bThe SSc–SLE combined P-values are calculated according to the inverse variance method, while the SSc or SLE analyses are performed according to the Mantel–Haenszel test for pooling ORs (see the Materials and methods section for moredetails).cP-values corrected for the first three principal components.

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  • the expression profile of this gene in the bioGPS public database(http://biogps.org/#goto=welcome); although this gene isexpressed ubiquitously, it has a particularly high expression inimmune cells such as macrophages, natural killer cells and otherhematopoietic cells in the mouse (Supplementary Material,Fig. S1) and CD33+ myeloid cells and CD14+ monocytes inhumans (Supplementary Material, Fig. S2). Meanwhile, PXKand JAZF1 were previously described as SLE genetic riskfactors (15,19). The role of these three genes in SLE pathogenesisremains largely unknown, it is also unclear whether their patho-genic mechanism is the same or different in SSc. However,PXK has been described to be involved in the trafficking of the epi-dermal growth factor receptor, which poses an attractive role inboth SSc and SLE (20). Furthermore, PXK has been describedto be associated only with autoantibody production in SLE in asmall cohort (21), analogously to what we have observed in SScin this study (Table 1). As of JAZF1, it has been associated withskeletal frame size and height, relating it to bone morphogenesisand collagen deposit (22,23), a key process in disorders affectingskin such as SSc and SLE.

    In GWAS data, we could classify the genetic associations intothree groups: Tier 1 for the GWAS-level associations (P , 5 ×1028), Tier 2 for suggestive associations (P , 5 × 1026) andTier 3 (all the remaining associations until 0.05). In the analysis

    of biological processes performed in this study (Table 3, Supple-mentary Material, Table S2), we used two sets of genes: first theTier 1 and Tier 2 associations (stronger associations in generalwith better P-values and ORs) and the Tier 3 associations, inwhich, should there be any true genetic association, it wouldbe weaker. When using all SNPs (translated to nearby genes)from Tiers 1 and 2 in this analysis, we observed that many bio-logical processes gathered under the immune system label areimportant for both SSc and SLE, which is to be expected. Stillin the Tier 1 and 2 associations, we see that signaling processes(cytokine mediated) and molting (to process by which the exter-nal layers of complex living beings is renewed) are also import-ant to SSc. In fact, we have already seen this in SSc geneticstudies which have described genes involved in morphogenesisand fibrosis to play a role in this disease (2,16,24). Conversely,when we perform the biological process analysis including theTier 3 genes, we observe that genes involved in the nervoussystem are important to both SSc and SLE (although differentspecific biological processes, Supplementary Material,Table S2) and cell adhesion is important to SSc. These biologicalprocesses being involved in SSc and SLE make sense based onthe current knowledge (25–33), but so far we have failed tofind the specific genetic markers which could induce the neuro-logical complications of SLE or SSc or cell adhesion in SSc.

    Often, the association of a genetic variant with a trait is re-ferred to by some gene in the same region, picked by its proxim-ity or functional attractiveness considering the studied trait.Nevertheless, we also wanted to asses whether any of thedescribed associations with SSc or SLE were in the sameregion and represented the same signal attributed by differentgenes. For this, we performed a GRAIL analysis (34), takinginto account all described genetic associations with a P-valueof ,5 × 1024 in the bibliography with any of the diseases. Asseen in Figure 3, all of the associated regions are representedby the previously described genes in those regions, with onenotable exception: in the genetic region represented by the asso-ciation of rs12540874, the association was attributed to GRB10in SSc (2) and to IKZF1 in SLE (15). Indeed, the signals were dif-ferent in the studies by Gorlova et al. and Harley et al., butaccording to the GRAIL analysis the most plausible associatedgene based on the current knowledge is IKZF1 (having connec-tions with 12 other genes in the analysis) rather than GRB10 (0connections according to the literature on the other genes).

    Due to the increased statistical power derived from themerging of two GWASs in SSc and SLE and the addition oflarge replication cohorts, we were able to establish one new func-tionally attractive susceptibility locus for SSc and SLE(KIAA0319L) and two new susceptibility loci for SSc (PXKand JAZF1) at GWAS level. This study, together with severalothers, adds evidence for the genetic continuum that underliesSSc, SLE and most autoimmune disorders.

    MATERIALS AND METHODS

    Study cohorts

    The GWAS cohorts analyzed in this study were composed of atotal of 3530 cases and 7381 healthy controls. Of these, 2761cases and 3720 healthy controls belonged to a previous SScGWAS conducted on cohorts from Spain, Germany, The

    Figure 2. Twin Manhattan plot representing the results of the SSc (left side, blue),SLE (right side, green) and combined GWAS analysis (both sides, grey).Selectedloci for replication in independent cohorts are marked in red. ∗SSc plotting repre-sents either the total disease or any of its considered subphenotypes, i.e. ACApositive, ATA positive, lcSSc and dcSSc. ∗∗ICA1 and JAZF1 SNPs were selectedaccording to selection criteria three (see Materials and methods), and not becauseof reaching the significance threshold in the GWAS stage.

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  • Netherlands and USA (16). The rest of the cases and controlsbelonged to a previously published SLE GWAS conducted inthe USA, SLEGEN cohort composed of 769 SLE patients and3661 healthy controls (15) (Supplementary Material, Tables S3and S4).

    We selected independent SSc and SLE replication cohorts inorder to confirm the results observed in the previousmeta-GWAS stage. The SSc replication cohort was composedof 432 cases and 380 controls from Spain, 691 cases and 241 con-trols from Italy and 455 cases and 2826 controls from the UK,while the SLE replication cohort was composed of 375 casesand 380 controls from Spain, 335 cases and 240 controls fromItaly and 1017 cases and 2826 controls from the UK (Supplemen-tary Material, Table S3). Supplementary Material, Table S4,shows key features of the SSc cohorts analyzed. All thesamples in the replication cohorts were recruited from hospitalsand clinics of each country after approval by the correspondingethics committees. Genotype data from the UK replication con-trols were obtained from the WTCCC data repositories, forwhich we were granted access.

    All cases either met the American College of Rheumatologypreliminary criteria for the classification of SSc (35) or had atleast three of the five CREST (calcinosis, Raynaud’s phenom-enon, esophageal dysmotility, sclerodactyly, telangiectasias)features and were classified according to their skin involvementand their auto-antibody production status (36,37). All SLEpatients in the current study fulfilled the revised criteria for clas-sification of SLE from the American College of Rheumatology(38). All individuals enrolled in the present study providedwritten informed consents.

    Data quality control

    GWAS data were filtered as previously described (16) using as alimits a 90% success call rate per SNP and individual, a deviationfrom the Hardy–Weinberg equilibrium of a P-value ,0.0001and a minor allele frequency ,1%. The first 10 principal compo-nents were estimated and individuals who deviated more thanthree standard deviations from the centroid of their populationin the first two principal components were excluded as outliers.The replication cohorts were filtered in the same way. The datafor PCA adjustment in the logistic regression were obtainedfrom Immunochip and GWAS data of our replication cohorts,except for the 455 SSc UK cases.

    Genotyping

    The GWAS genotyping of the SSc cases and controls was per-formed as follows: the Spanish SSc cases and controls togetherwith Dutch and German SSc cases were genotyped at the Depart-ment of Medical Genetics of the University Medical CenterUtrecht (The Netherlands) using the commercial release IlluminaHuman CNV370K BeadChip. Genotype data for Dutch andGerman controls were obtained from the Illumina Human550KBeadChip available from a previous study. The SSc casegroup from the USAwas genotypedat the Boas Center for Genom-ics and Human Genetics, Feinstein Institute for Medical Research,North Shore Long Island Jewish Health System using the IlluminaHuman 610-Quad BeadChip. CGEMS and Illumina iControlDBcontrols were genotyped on the Illumina Hap550KBeadChip.SNPs selected for the replication phase were genotyped in the

    Table 2. Expression data of the successfully replicated loci from Table 1, whether at GWAS level or suggestive level of association

    Chr. Gene SSc versus controls SLE versus controlsParametric P FDR Fold change Parametric P FDR Fold change

    1 KIAA0319L 9.05E203 1.43E201 1.328 5.36E205 2.94E203 1.9373 PXK NDa NDa NDa NDa NDa NDa

    7 JAZF1 9.04E201 9.60E201 0.990 3.90E201 6.17E201 0.870

    Significantly overexpressed genes are marked in bold.aPXK was not sufficiently expressed in whole blood samples and did not pass the filtering criteria.

    Table 3. Significantly overrepresented groups of biological processes among the genes associated with either SSc or SLE and whether they are shared betweenthem or not

    Disease SNP selectiona Group Top biological process Shared Significant processes GO term Best P-valueb

    SSc 5.00E206 Immune system Cellular response to interferon-gamma Yes 27 GO:0071346 2.05E213SSc 5.00E206 Signaling Cytokine-mediated signaling pathway No 8 GO:0019221 4.57E211SSc 0.05 Nervous system Transmission of nerve impulse No 3 GO:0019226 9.71E210SSc 5.00E206 Molting Exogen No 7 GO:0042638 2.61E209SSc 0.05 Cell adhesion Cell adhesion No 4 GO:0007155 3.29E209SLE 5.00E206 Immune system Cellular response to interferon-gamma Yes 8 GO:0071346 2.14E208SLE 0.05 Nervous system Nervous system development No 4 GO:0007399 1.34E207

    Significantly overrepresented biological processes are marked in bold.aThreshold P-value for SNP selection from the GWAS data for the biological process analyses.bThe P-value for the FDR-corrected hypergeometric test for the most associated biological process for this group (see the Materials and methods section for moredetails).

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  • replication cohorts using Applied Biosystems’ TaqMan SNPassays on ABI Prism 7900 HT real-time thermocyclers.

    Study design

    Considering the size of our cohort for both study phases, simul-taneously we calculated the statistical power for the differentscenarios according to Skol et al. (39). Supplementary Material,Table S1, shows the statistical power to detect different effectsizes. On average, we had 86% statistical power to detect anOR of 1.20 with a minor allele frequency of 0.20.

    Taking this into consideration, for the GWAS analysis threedifferent criteria were followed to select SNPs for replicationand maximization of our success in signal detection:

    (1) In order to detect common signals for SSc and SLE whichcaused either risk or protection in both diseases, we selectedSNPs that showed a P-value of the SSc and SLE meta-analysis,5 × 1027and showed a nominally significant associationwith both diseases at a P-value of ,0.05, as well as no signifi-cant heterogeneity in the SSc cohorts meta-analysis (Q .0.05) (Supplementary Material, Table S5).

    (2) To detect common signals for SSc and SLE which causedeither risk or protection in one of the diseases and the oppositeeffect in the other, we selected SNPs that showed a P-value ofthe SSc and SLE meta-analysis (using for SLE in this case 1/OR instead of the OR) ,5 × 1027 and were associated withboth a P-value of , 0.05 in both diseases, and without signifi-cant heterogeneity in the SSc cohorts meta-analysis (Q .0.05) (Supplementary Material, Table S6).

    (3) To further detect any susceptibility variants previouslyreported for one of the diseases but not reported for theother, we selected any SNP with an overall P-value of

    ,5 × 1025 and associated separately in SSc and SLE (at aP-value of ,0.05) which had been previously describedas a genetic risk factor for either disease (SupplementaryMaterial, Table S7).

    In any of these cases when performing the pan-meta-analysis ofSSc and SLE, we also considered the most frequent SSc subphe-notypes (classified as stated above): anti-centromere antibody(ACA) positive subgroup, anti-topoisomerase I antibody (ATA)positive subgroup, limited cutaneous subtype (lcSSc) anddiffuse cutaneous subtype (dcSSc) (36,37). Supplementary Ma-terial, Figure S3, shows from which subphenotype of SSc eachof the selected SNPs was derived from for the replication step.

    After the replication stage was completed, we considered asignal to be statistically significant if the combined (SSc andSLE, GWAS and replication cohorts) meta-analysis P-valuewas ,5 × 1028, and if the meta-analysis P-value (GWASand replication cohorts) for each disease and stage was alsosignificant.

    Statistical analysis

    Meta-analysis of the SSc GWAS data was performed with theCochran–Mantel–Haenszel test correcting for the genomic in-flation factor lambda (GC correction) (Supplementary Material,Fig. S4). Analysis of the SLE GWAS data was performed by asimple x2 2 × 2 test correcting the P-values for the genomic in-flation factor lambda (GC correction) (Supplementary Material,Fig. S4). The pan-meta-analysis of the SSc and SLE GWAS datawas performed using the inverse variance method calculating theresulting ORs. When the replication cohorts were included in theanalysis, they were also analyzed using the inverse variancemethod. The analysis of the GWAS and replication cohorts to-gether was also performed by means of logistic regression ana-lysis using the first three principal components as covariates inorder to rule out any population stratification effect. When differ-ent associations were found in the same locus, the underlying as-sociation hit was determined by means of conditional logisticregression analysis. All statistical analyses were performedusing Plink version 1.07 (40) (http://pngu.mgh.harvard.edu/~purcell/plink/) and HelixTree SNP Variation Suite 7 (http://www.goldenhelix.com/).

    Biological process analysis

    We performed the biological process analysis of the SSc andSLE GWAS data according to Zhang et al. (41). For this, we per-formed two analyses on each disease, one selecting all SNPs witha P-value ,0.05 and the other selecting all SNPs with a P-value,5 × 1026. In both the cases, the test to determine whether abiological process (GO term) was overrepresented amongGWAS associations was performed by means of a hypergeo-metric test with a cutoff P-value of 5 × 1026. All P-values inthese analyses were multiple testing corrected according toHochberg and Benjamini (42).

    Gene expression Data

    We had access to whole blood gene expression data from 74 SScpatients, 17 SLE patients and 21 healthy controls (43); which

    Figure 3. GRAIL analysis of all the described susceptibility loci for SSc and/orSLE with P , 5 × 1024. The release 18 of the human genome and the PubMedtext as of 2012 were used for the GRAIL analysis.

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  • were not included in the GWAS cohorts. None of the patientswere treated with immunosuppressive agents (exception pred-nisone ≤5 mg or hydroxychloroquine). Blood samples for tran-script studies were drawn directly into PAXgene tubes(PreAnalytiX, Franklin Lakes, NJ, USA). Total RNA was iso-lated according to the manufacturer’s protocol using thePAXgene RNA kit (PreAnalytiX). The RNA quality and yieldwere assessed using a 2100 Bioanalyzer (Agilent, Palo Alto,CA, USA) and an ND-1000 Spectrophotometer (NanoDropTechnologies, Wilmington, DE, USA). Two hundred nano-grams of total RNA were amplified and purified using the Illu-mina TotalPrep RNA Amplification kit (Applied Biosystems/Ambion, Austin, TX, USA) in accordance with the manufac-turer’s instructions. The amplified complementary RNA washybridized on Illumina Human Ref-8 BeadChips, and the datawere extracted with the Illumina Beadstudio software suite (Illu-mina, San Diego, CA, USA). A transcript was defined as differ-entially expressed when the significance level for comparisonwas P ≤ 0.05 and the FDR was ≤0.10 using a random-variancet-test.

    SUPPLEMENTARY MATERIAL

    Supplementary Material is available at HMG online.

    ACKNOWLEDGEMENTS

    We thank Sofia Vargas, Sonia Garcia and Gema Robledo fortheir excellent technical assistance, and all the patients andhealthy controls for kindly accepting their essential collabor-ation. We also thank the following organizations: the EULARScleroderma Trials and Research (EUSTAR), the GermanNetwork of Systemic Sclerosis and Banco Nacional de ADN(University of Salamanca, Spain).

    FUNDING

    This work was supported by the following grants: J.M. wasfunded by GEN-FER from the Spanish Society of Rheumatol-ogy, SAF2009-11110 and SAF2012-34435 from the Ministeriode Economia y Competitividad, CTS-4977 from Junta deAndalucı́a (Spain), Redes Temáticas de Investigación Coopera-tiva Sanitaria Program, RD08/0075 (RIER) from Instituto deSalud Carlos III (ISCIII, Spain), Fondo Europeo de DesarrolloRegional (FEDER) and the grant NIH NIAID1U01AI09090-01. T.R.D.J.R. was funded by the VIDI laureatefrom the Dutch Association of Research (NWO) and Dutch Arth-ritis Foundation (National Reumafonds) and is an ERC startinggrant Laureate 2011. J.M. and T.R.D.J.R. were sponsored bythe Orphan Disease Program grant from the European LeagueAgainst Rheumatism (EULAR). B.P.C.K. is supported by theDutch Diabetes Research Foundation (grant 2008.40.001) andthe Dutch Arthritis Foundation (Reumafonds, grant NR09-1-408). S.A. and M.D.M. were supported by NIH/NIAMSScleroderma Family Registry and DNA Repository(N01-AR-0-2251), NIH/NIAMS-RO1- AR055258, and NIH/NIAMS Center of Research Translation in Scleroderma(1P50AR054144), the Department of Defense CongressionallyDirected Medical Research Programs (W81XWH-07-01-0111),

    and K23-AR-061436. M.E.A.R. was funded by the Instituto deSalud Carlos III partially through FEDER funds of the EuropeanUnion (PS09/00129), la Consejerı́a de Salud de Andalucı́a(PI0012), la Fundación Ramón Areces and the Swedish ResearchCouncil. M.E.A.R. is the Chairman of the BIOLUPUS networkfunded by the European Science Foundation. T.W. is funded bythe grant KFO 250, TP03, WI 1031/6-1.

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