A multicenter study confirms CD226 gene association with systemic sclerosis-related pulmonary fibrosis

Introduction: CD226 genetic variants have been associated with a number of autoimmune diseases and recently with systemic sclerosis (SSc). The aim of this study was to test the influence of CD226 loci in SSc susceptibility, clinical phenotypes and autoantibody status in a large multicenter European population. Methods: A total of seven European populations of Caucasian ancestry were included, comprising 2,131 patients with SSc and 3,966 healthy controls. Three CD226 single nucleotide polymorphisms (SNPs), rs763361, rs3479968 and rs727088, were genotyped using Taqman 5’allelic discrimination assays. Results: Pooled analyses showed no evidence of association of the three SNPs, neither with the global disease nor with the analyzed subphenotypes. However, haplotype block analysis revealed a significant association for the TCG haplotype (SNP order: rs763361, rs34794968, rs727088) with lung fibrosis positive patients (PBonf = 3.18E-02 OR 1.27 (1.05 to 1.54)). Conclusion: Our data suggest that the tested genetic variants do not individually influence SSc susceptibility but a CD226 three-variant haplotype is related with genetic predisposition to SSc-related pulmonary fibrosis.We thank Sofia Vargas, Sonia García and Gema Robledo for their excellent technical assistance and all the patients and control donors for their essential collaboration. We thank Banco Nacional de ADN (University of Salamanca, Spain) and the Norwegian Bone Marrow Donor Registry, who supplied part of the control DNA samples. We are also thankful to EUSTAR (the EULAR Scleroderma Trials and Research group) and the German Network of Systemic Sclerosis for the facilitation of this project. This work was supported by the following grants: JM was funded by GEN-FER from the Spanish Society of Rheumatology, SAF2009-11110 from the Spanish Ministry of Science, CTS-4977 from Junta de Andalucía, Spain, in part by Redes Temáticas de Investigación Cooperativa Sanitaria Program, RD08/0075 (RIER) from Instituto de Salud Carlos III (ISCIII), Spain and by Fondo Europeo de Desarrollo Regional (FEDER). TRDJR was funded by the VIDI laureate from the Dutch Association of Research (NWO) and Dutch Arthritis Foundation (National Reumafonds). JM and TRDJR were sponsored by the Orphan Disease Program grant from the European League Against Rheumatism (EULAR). BPCK is supported by the Dutch Diabetes Research Foundation (grant 2008.40.001) and the Dutch Arthritis Foundation (Reumafonds, grant NR 09-1-408). TW was granted by DFG WI 1031/6.1. This study was also funded by PI-0590-2010, Consejería de Salud, Junta de Andalucía, Spain. The Spanish Scleroderma Group: Norberto Ortego-Centeno and Jose Luis Callejas, Unidad de Enfermedades Sistémicas Autoinmunes, Servicio de Medicina Interna, Hospital Clínico Universitario San Cecilio, Granada; Nuria Navarrete, Servicio de Medicina Interna, Hospital Virgen de las Nieves, Granada; Rosa García Portales, Servicio de Reumatología, Hospital Virgen de la Victoria, Málaga; Antonio Fernández-Nebro, Servicio de Reumatología, Hospital Carlos Haya, Málaga; María F. González-Escribano, Servicio de Inmunología, Hospital Virgen del Rocío, Sevilla; Julio Sánchez-Román and Francisco José García-Hernández, Servicio de Medicina Interna, Hospital Virgen del Rocío, Sevilla; Mª Ángeles Aguirre and Inmaculada Gómez-Gracia, Servicio de Reumatología, Hospital Reina Sofía, Córdoba; Benjamín Fernández-Gutiérrez and Luis Rodríguez-Rodríguez, Servicio de Reumatología, Hospital Clínico San Carlos, Madrid; José Luis Andreu and Mónica Fernández de Castro, Servicio de Reumatología, Hospital Puerta del Hierro, Madrid; Paloma García de la Peña, Servicio de Reumatología, Hospital Madrid Norte Sanchinarro, Madrid; Francisco Javier López-Longo and Lina Martínez, Servicio de Reumatología, Hospital General Universitario Gregorio Marañón, Madrid; Vicente Fonollosa, Servicio de Medicina Interna, Hospital Valle de Hebrón, Barcelona; Iván Castellví, Servicio de Reumatología, Hospital Sant Pau, Barcelona; Anna Pros, Servicio de Reumatología, Hospital Del Mar, Barcelona; Mónica Rodríguez Carballeira, Servicio de Medicina Interna, Hospital Universitari Mútua Terrasa, Barcelona; Bernardino Díaz, Luis Trapiella and María Gallego, Servicio de Medicina Interna, Hospital Central de Asturias, Oviedo; Inés Vaqueiro, Unidad de Trombosis y Vasculitis, Servicio de Medicina Interna, Hospital Xeral-Complexo Hospitalario Universitario de Vigo, Vigo; María Victoria Egurbide, Servicio de Medicina Interna, Hospital de Cruces, Barakaldo; Luis Sáez-Comet, Unidad de Enfermedades Autoinmunes Sistémicas, Servicio de Medicina Interna, Hospital Universitario Miguel Servet, Zaragoza; Federico Díaz and Vanesa Hernández, Servicio de Reumatología, Hospital Universitario de Canarias, Tenerife; José Andrés Román-Ivorra, Servicio de Reumatología, Hospital Universitari i Politecnic La Fe, Valencia

Identification of novel genetic markers associated with clinical phenotypes of systemic sclerosis through a genome-wide association strategy

The aim of this study was to determine, through a genome-wide association study (GWAS), the genetic components contributing to different clinical sub-phenotypes of systemic sclerosis (SSc). We considered limited (lcSSc) and diffuse (dcSSc) cutaneous involvement, and the relationships with presence of the SSc-specific auto-antibodies, anti-centromere (ACA), and anti-topoisomerase I (ATA). Four GWAS cohorts, comprising 2,296 SSc patients and 5,171 healthy controls, were meta-analyzed looking for associations in the selected subgroups. Eighteen polymorphisms were further tested in nine independent cohorts comprising an additional 3,175 SSc patients and 4,971 controls. Conditional analysis for associated SNPs in the HLA region was performed to explore their independent association in antibody subgroups. Overall analysis showed that non-HLA polymorphism rs11642873 in IRF8 gene to be associated at GWAS level with lcSSc (P = 2.32×10−12, OR = 0.75). Also, rs12540874 in GRB10 gene (P = 1.27 × 10−6, OR = 1.15) and rs11047102 in SOX5 gene (P = 1.39×10−7, OR = 1.36) showed a suggestive association with lcSSc and ACA subgroups respectively. In the HLA region, we observed highly associated allelic combinations in the HLA-DQB1 locus with ACA (P = 1.79×10−61, OR = 2.48), in the HLA-DPA1/B1 loci with ATA (P = 4.57×10−76, OR = 8.84), and in NOTCH4 with ACA P = 8.84×10−21, OR = 0.55) and ATA (P = 1.14×10−8, OR = 0.54). We have identified three new non-HLA genes (IRF8, GRB10, and SOX5) associated with SSc clinical and auto-antibody subgroups. Within the HLA region, HLA-DQB1, HLA-DPA1/B1, and NOTCH4 associations with SSc are likely confined to specific auto-antibodies. These data emphasize the differential genetic components of subphenotypes of SSc.This work was supported by the following grants: J Martin was funded by GEN-FER from the Spanish Society of Rheumatology, SAF2009-11110 from the Spanish Ministry of Science, CTS-4977 from Junta de Andalucı´a, Spain, and in part by Redes Tema´ticas de Investigacio´n Cooperativa Sanitaria Program, RD08/0075 (RIER) from Instituto de Salud Carlos III (ISCIII), Spain. TRDJ Radstake was funded by the VIDI laureate from the Dutch Association of Research (NWO) and Dutch Arthritis Foundation (National Reumafonds). J Martin and TRDJ Radstake were sponsored by the Orphan Disease Program grant from the European League Against Rheumatism (EULAR). BPC Koeleman is supported by the Dutch Diabetes Research Foundation (grant 2008.40.001) and the Dutch Arthritis Foundation (Reumafonds, grant NR 09-1-408). BZ Alizadeh is supported by the Netherlands Organization for Health Research and Development (ZonMW grant 016.096.121). Genotyping of the Dutch control samples was sponsored by US National Institutes of Mental Health funding, R01 MH078075 (ROA). The German controls were from the PopGen biobank (to BPC Koeleman). The PopGen project received infrastructure support through the German Research Foundation excellence cluster ‘‘Inflammation at Interfaces.’’ The USA studies were supported by NIH/NIAMS Scleroderma Family Registry and DNA Repository (N01-AR-0-2251), NIH/NIAMS-RO1-AR055258, NIH/NIAMS Center of Research Translation in Scleroderma (1P50AR054144), and the Department of Defense Congressionally Directed Medical Research Programs (W81XWH-07-01-0111). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

The systemic lupus erythematosus IRF5 risk haplotype is associated with systemic sclerosis

Systemic sclerosis (SSc) is a fibrotic autoimmune disease in which the genetic component plays an important role. One of the strongest SSc association signals outside the human leukocyte antigen (HLA) region corresponds to interferon (IFN) regulatory factor 5 (IRF5), a major regulator of the type I IFN pathway. In this study we aimed to evaluate whether three different haplotypic blocks within this locus, which have been shown to alter the protein function influencing systemic lupus erythematosus (SLE) susceptibility, are involved in SSc susceptibility and clinical phenotypes. For that purpose, we genotyped one representative single-nucleotide polymorphism (SNP) of each block (rs10488631, rs2004640, and rs4728142) in a total of 3,361 SSc patients and 4,012 unaffected controls of Caucasian origin from Spain, Germany, The Netherlands, Italy and United Kingdom. A meta-analysis of the allele frequencies was performed to analyse the overall effect of these IRF5 genetic variants on SSc. Allelic combination and dependency tests were also carried out. The three SNPs showed strong associations with the global disease (rs4728142: P = 1.34×10<sup>−8</sup>, OR = 1.22, CI 95% = 1.14–1.30; rs2004640: P = 4.60×10<sup>−7</sup>, OR = 0.84, CI 95% = 0.78–0.90; rs10488631: P = 7.53×10<sup>−20</sup>, OR = 1.63, CI 95% = 1.47–1.81). However, the association of rs2004640 with SSc was not independent of rs4728142 (conditioned P = 0.598). The haplotype containing the risk alleles (rs4728142*A-rs2004640*T-rs10488631*C: P = 9.04×10<sup>−22</sup>, OR = 1.75, CI 95% = 1.56–1.97) better explained the observed association (likelihood P-value = 1.48×10<sup>−4</sup>), suggesting an additive effect of the three haplotypic blocks. No statistical significance was observed in the comparisons amongst SSc patients with and without the main clinical characteristics. Our data clearly indicate that the SLE risk haplotype also influences SSc predisposition, and that this association is not sub-phenotype-specific

Analysis of the association between CD40 and CD40 ligand polymorphisms and systemic sclerosis.

Introduction: The aim of the present study was to investigate the possible role of CD40 and CD40 ligand (CD40LG) genes in the susceptibility and phenotype expression of systemic sclerosis (SSc). Methods: In total, 2,670 SSc patients and 3,245 healthy individuals from four European populations (Spain, Germany, The Netherlands, and Italy) were included in the study. Five single-nucleotide polymorphisms (SNPs) of CD40 (rs1883832, rs4810485, rs1535045) and CD40LG (rs3092952, rs3092920) were genotyped by using a predesigned TaqMan allele-discrimination assay technology. Meta-analysis was assessed to determine whether an association exists between the genetic variants and SSc or its main clinical subtypes. Results: No evidence of association between CD40 and CD40LG genes variants and susceptibility to SSc was observed. Similarly, no significant statistical differences were observed when SSc patients were stratified by the clinical subtypes, the serologic features, and pulmonary fibrosis. Conclusions: Our results do not suggest an important role of CD40 and CD40LG gene polymorphisms in the susceptibility to or clinical expression of SSc

A genome-wide association study follow-up suggests a possible role for PPARG in systemic sclerosis susceptibility

Introduction: A recent genome-wide association study (GWAS) comprising a French cohort of systemic sclerosis (SSc) reported several non-HLA single-nucleotide polymorphisms (SNPs) showing a nominal association in the discovery phase. We aimed to identify previously overlooked susceptibility variants by using a follow-up strategy.<p></p> Methods: Sixty-six non-HLA SNPs showing a P value <10-4 in the discovery phase of the French SSc GWAS were analyzed in the first step of this study, performing a meta-analysis that combined data from the two published SSc GWASs. A total of 2,921 SSc patients and 6,963 healthy controls were included in this first phase. Two SNPs, PPARG rs310746 and CHRNA9 rs6832151, were selected for genotyping in the replication cohort (1,068 SSc patients and 6,762 healthy controls) based on the results of the first step. Genotyping was performed by using TaqMan SNP genotyping assays. Results: We observed nominal associations for both PPARG rs310746 (PMH = 1.90 × 10-6, OR, 1.28) and CHRNA9 rs6832151 (PMH = 4.30 × 10-6, OR, 1.17) genetic variants with SSc in the first step of our study. In the replication phase, we observed a trend of association for PPARG rs310746 (P value = 0.066; OR, 1.17). The combined overall Mantel-Haenszel meta-analysis of all the cohorts included in the present study revealed that PPARG rs310746 remained associated with SSc with a nominal non-genome-wide significant P value (PMH = 5.00 × 10-7; OR, 1.25). No evidence of association was observed for CHRNA9 rs6832151 either in the replication phase or in the overall pooled analysis.<p></p> Conclusion: Our results suggest a role of PPARG gene in the development of SSc

Immunochip analysis identifies multiple susceptibility loci for systemic sclerosis

In this study, 1,833 systemic sclerosis (SSc) cases and 3,466 controls were genotyped with the Immunochip array. Classical alleles, amino acid residues, and SNPs across the human leukocyte antigen (HLA) region were imputed and tested. These analyses resulted in a model composed of six polymorphic amino acid positions and seven SNPs that explained the observed significant associations in the region. In addition, a replication step comprising 4,017 SSc cases and 5,935 controls was carried out for several selected non-HLA variants, reaching a total of 5,850 cases and 9,401 controls of European ancestry. Following this strategy, we identified and validated three SSc risk loci, including DNASE1L3 at 3p14, the SCHIP1-IL12A locus at 3q25, and ATG5 at 6q21, as well as a suggested association of the TREH-DDX6 locus at 11q23. The associations of several previously reported SSc risk loci were validated and further refined, and the observed peak of association in PXK was related to DNASE1L3. Our study has increased the number of known genetic associations with SSc, provided further insight into the pleiotropic effects of shared autoimmune risk factors, and highlighted the power of dense mapping for detecting previously overlooked susceptibility loci

Analysis of the association between CD40 and CD40 ligand polymorphisms and systemic sclerosis

Journal Article; Research Support, Non-U.S. Gov't;INTRODUCTION The aim of the present study was to investigate the possible role of CD40 and CD40 ligand (CD40LG) genes in the susceptibility and phenotype expression of systemic sclerosis (SSc). METHODS In total, 2,670 SSc patients and 3,245 healthy individuals from four European populations (Spain, Germany, The Netherlands, and Italy) were included in the study. Five single-nucleotide polymorphisms (SNPs) of CD40 (rs1883832, rs4810485, rs1535045) and CD40LG (rs3092952, rs3092920) were genotyped by using a predesigned TaqMan allele-discrimination assay technology. Meta-analysis was assessed to determine whether an association exists between the genetic variants and SSc or its main clinical subtypes. RESULTS No evidence of association between CD40 and CD40LG genes variants and susceptibility to SSc was observed. Similarly, no significant statistical differences were observed when SSc patients were stratified by the clinical subtypes, the serologic features, and pulmonary fibrosis. CONCLUSIONS Our results do not suggest an important role of CD40 and CD40LG gene polymorphisms in the susceptibility to or clinical expression of SSc.Ye

New insight on the Xq28 association with systemic sclerosis

Objective: To evaluate whether the systemic sclerosis (SSc)-associated IRAK1 non-synonymous single-nucleotide polymorphism rs1059702 is responsible for the Xq28 association with SSc or whether there are other independent signals in the nearby methyl-CpG-binding protein 2 gene (MECP2). Methods: We analysed a total of 3065 women with SSc and 2630 unaffected controls from five independent Caucasian cohorts. Four tag single-nucleotide polymorphisms of MECP2 (rs3027935, rs17435, rs5987201 and rs5945175) and the IRAK1 variant rs1059702 were genotyped using TaqMan predesigned assays. A meta-analysis including all cohorts was performed to test the overall effect of these Xq28 polymorphisms on SSc. Results: IRAK1 rs1059702 and MECP2 rs17435 were associated specifically with diffuse cutaneous SSc (PFDR=4.12×10−3, OR=1.27, 95% CI 1.09 to 1.47, and PFDR=5.26×10−4, OR=1.30, 95% CI 1.14 to 1.48, respectively), but conditional logistic regression analysis showed that the association of IRAK1 rs1059702 with this subtype was explained by that of MECP2 rs17435. On the other hand, IRAK1 rs1059702 was consistently associated with presence of pulmonary fibrosis (PF), because statistical significance was observed when comparing SSc patients PF+ versus controls (PFDR=0.039, OR=1.30, 95% CI 1.07 to 1.58) and SSc patients PF+ versus SSc patients PF− (p=0.025, OR=1.26, 95% CI 1.03 to 1.55). Conclusions: Our data clearly suggest the existence of two independent signals within the Xq28 region, one located in IRAK1 related to PF and another in MECP2 related to diffuse cutaneous SSc, indicating that both genes may have an impact on the clinical outcome of the disease

Analysis of the association between CD40 and CD40 ligand polymorphisms and systemic sclerosis

Introduction: The aim of the present study was to investigate the possible role of CD40 and CD40 ligand (CD40LG) genes in the susceptibility and phenotype expression of systemic sclerosis (SSc). Methods: In total, 2,670 SSc patients and 3,245 healthy individuals from four European populations (Spain, Germany, The Netherlands, and Italy) were included in the study. Five single-nucleotide polymorphisms (SNPs) of CD40 (rs1883832, rs4810485, rs1535045) and CD40LG (rs3092952, rs3092920) were genotyped by using a predesigned TaqMan allele-discrimination assay technology. Meta-analysis was assessed to determine whether an association exists between the genetic variants and SSc or its main clinical subtypes. Results: No evidence of association between CD40 and CD40LG genes variants and susceptibility to SSc was observed. Similarly, no significant statistical differences were observed when SSc patients were stratified by the clinical subtypes, the serologic features, and pulmonary fibrosis. Conclusions: Our results do not suggest an important role of CD40 and CD40LG gene polymorphisms in the susceptibility to or clinical expression of SSc