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ObjectivesSystemic sclerosis (SSc) is an autoimmune disease characterised by skin and systemic fibrosis culminating in organ damage. Previous genetic studies including genome-wide association studies (GWAS) have identified 12 susceptibility loci satisfying genome-wide significance. Transethnic meta-analyses have successfully expanded the list of susceptibility genes and deepened biological insights for other autoimmune diseases.MethodsWe performed transethnic meta-analysis of GWAS in the Japanese and European populations, followed by a two-staged replication study comprising a total of 4436 cases and 14 751 controls. Associations between significant single nuclear polymorphisms (SNPs) and neighbouring genes were evaluated. Enrichment analysis of H3K4Me3, a representative histone mark for active promoter was conducted with an expanded list of SSc susceptibility genes.ResultsWe identified two significant SNP in two loci, GSDMA and PRDM1, both of which are related to immune functions and associated with other autoimmune diseases (p=1.4×10−10 and 6.6×10−10, respectively). GSDMA also showed a significant association with limited cutaneous SSc. We also replicated the associations of previously reported loci including a non-GWAS locus, TNFAIP3. PRDM1 encodes BLIMP1, a transcription factor regulating T-cell proliferation and plasma cell differentiation. The top SNP in GSDMA was a missense variant and correlated with gene expression of neighbouring genes, and this could explain the association in this locus. We found different human leukocyte antigen (HLA) association patterns between the two populations. Enrichment analysis suggested the importance of CD4-naïve primary T cell.ConclusionsGSDMA and PRDM1 are associated with SSc. These findings provide enhanced insight into the genetic and biological basis of SSc.

Systemic sclerosis (SSc) is an orphan, complex, inflammatory disease affecting the immune system and connective tissue. SSc stands out as a severely incapacitating and life-threatening inflammatory rheumatic disease, with a largely unknown pathogenesis. We have designed a two-stage genome-wide association study of SSc using case-control samples from France, Italy, Germany, and Northern Europe. The initial genome-wide scan was conducted in a French post quality-control sample of 564 cases and 1,776 controls, using almost 500 K SNPs. Two SNPs from the MHC region, together with the 6 loci outside MHC having at least one SNP with a P<10(-5) were selected for follow-up analysis. These markers were genotyped in a post-QC replication sample of 1,682 SSc cases and 3,926 controls. The three top SNPs are in strong linkage disequilibrium and located on 6p21, in the HLA-DQB1 gene: rs9275224, P = 9.18×10(-8), OR = 0.69, 95% CI [0.60-0.79]; rs6457617, P = 1.14×10(-7) and rs9275245, P = 1.39×10(-7). Within the MHC region, the next most associated SNP (rs3130573, P = 1.86×10(-5), OR = 1.36 [1.18-1.56]) is located in the PSORS1C1 gene. Outside the MHC region, our GWAS analysis revealed 7 top SNPs (P<10(-5)) that spanned 6 independent genomic regions. Follow-up of the 17 top SNPs in an independent sample of 1,682 SSc and 3,926 controls showed associations at PSORS1C1 (overall P = 5.70×10(-10), OR:1.25), TNIP1 (P = 4.68×10(-9), OR:1.31), and RHOB loci (P = 3.17×10(-6), OR:1.21). Because of its biological relevance, and previous reports of genetic association at this locus with connective tissue disorders, we investigated TNIP1 expression. A markedly reduced expression of the TNIP1 gene and also its protein product were observed both in lesional skin tissue and in cultured dermal fibroblasts from SSc patients. Furthermore, TNIP1 showed in vitro inhibitory effects on inflammatory cytokine-induced collagen production. The genetic signal of association with TNIP1 variants, together with tissular and cellular investigations, suggests that this pathway has a critical role in regulating autoimmunity and SSc pathogenesis.

Background Systemic sclerosis (SSc)-overlap syndromes are a very heterogeneous and remarkable subgroup of SSc-patients, who present at least two connective tissue diseases (CTD) at the same time, usually with a specific autoantibody status. Objectives To determine whether patients, classified as overlap syndromes, show a disease course different from patients with limited SSc (lcSSc) or diffuse cutaneous SSc (dcSSc). Methods The data of 3240 prospectively included patients, registered in the database of the German Network for Systemic Scleroderma and followed between 2003 and 2013, were analysed. Results Among 3240 registered patients, 10% were diagnosed as SSc-overlap syndrome. Of these, 82.5% were female. SSc-overlap patients had a mean age of 48±1.2 years and carried significantly more often ‘other antibodies’ (68.0%; p<0.0001), including anti-U1RNP, -PmScl, -Ro, -La, as well as anti-Jo-1 and -Ku antibodies. These patients developed musculoskeletal involvement earlier and more frequently (62.5%) than patients diagnosed as lcSSc (32.2%) or dcSSc (43.3%) (p<0.0001). The onset of lung fibrosis and heart involvement in SSc-overlap patients was significantly earlier than in patients with lcSSc and occurred later than in patients with dcSSc. Oesophagus, kidney and PH progression was similar to lcSSc patients, whereas dcSSc patients had a significantly earlier onset. Conclusions These data support the concept that SSc-overlap syndromes should be regarded as a separate SSc subset, distinct from lcSSc and dcSSc, due to a different progression of the disease, different proportional distribution of specific autoantibodies, and of different organ involvement.

Rheumatoid arthritis (RA) is a major cause of adult chronic inflammatory arthritis and a typical complex trait. Although several genetic determinants have been identified, they account for only a part of the genetic susceptibility. We conducted a genome-wide association study of RA in Japanese using 225,079 SNPs genotyped in 990 cases and 1,236 controls from two independent collections (658 cases and 934 controls in collection1; 332 cases and 302 controls in collection2), followed by replication studies in two additional collections (874 cases and 855 controls in collection3; 1,264 cases and 948 controls in collection4). SNPs showing p<0.005 in the first two collections and p<10(-4) by meta-analysis were further genotyped in the latter two collections. A novel risk variant, rs2000811, in intron2 of the myelin basic protein (MBP) at chromosome 18q23 showed strong association with RA (p = 2.7×10(-8), OR 1.23, 95% CI: 1.14-1.32). The transcription of MBP was significantly elevated with the risk allele compared to the alternative allele (p<0.001). We also established by immunohistochemistry that MBP was expressed in the synovial lining layer of RA patients, the main target of inflammation in the disease. Circulating autoantibody against MBP derived from human brain was quantified by ELISA between patients with RA, other connective tissue diseases and healthy controls. As a result, the titer of anti-MBP antibody was markedly higher in plasma of RA patients compared to healthy controls (p<0.001) and patients with other connective tissue disorders (p<0.001). ELISA experiment using citrullinated recombinant MBP revealed that a large fraction of anti-MBP antibody in RA patients recognized citrullinated MBP. This is the first report of a genetic study in RA implicating MBP as a potential autoantigen and its involvement in pathogenesis of the disease.

Genome integrity is continuously challenged by the DNA damage that arises during normal cell metabolism. Biallelic mutations in the genes encoding the genome surveillance enzyme ribonuclease H2 (RNase H2) cause Aicardi-Goutières syndrome (AGS), a pediatric disorder that shares features with the autoimmune disease systemic lupus erythematosus (SLE). Here we determined that heterozygous parents of AGS patients exhibit an intermediate autoimmune phenotype and demonstrated a genetic association between rare RNASEH2 sequence variants and SLE. Evaluation of patient cells revealed that SLE- and AGS-associated mutations impair RNase H2 function and result in accumulation of ribonucleotides in genomic DNA. The ensuing chronic low level of DNA damage triggered a DNA damage response characterized by constitutive p53 phosphorylation and senescence. Patient fibroblasts exhibited constitutive upregulation of IFN-stimulated genes and an enhanced type I IFN response to the immunostimulatory nucleic acid polyinosinic:polycytidylic acid and UV light irradiation, linking RNase H2 deficiency to potentiation of innate immune signaling. Moreover, UV-induced cyclobutane pyrimidine dimer formation was markedly enhanced in ribonucleotide-containing DNA, providing a mechanism for photosensitivity in RNase H2-associated SLE. Collectively, our findings implicate RNase H2 in the pathogenesis of SLE and suggest a role of DNA damage-associated pathways in the initiation of autoimmunity.

Abstract Rheumatoid arthritis (RA) is a common systemic autoimmune disease and its onset and prognosis are controlled by genetic, immunological, and environmental factors. The HLA locus, particularly HLA-DRB1, is its strongest genetic risk determinant across ethnicities. Several other genes, including PTPN22 and PADI4, show modest association with RA. However, they cover only a part of its genetic components and their relative contribution is different between populations. To identify novel genetic determinants, we took a candidate gene approach in a trans-ethnic manner. After critical selection of 169 genes based on their immunological function, we performed SNP discovery of these genes by the resequencing of exons and surrounding areas using European and Japanese DNAs. We then generated a panel of 1,509 SNPs for case-control association study in both populations. The DerSimonian-Laird test for meta-analysis, using the combined results of the two populations, identified rs7551957 at the 5′-flanking region of the low-affinity Fc-gamma receptor IIa (FCGR2A) gene as the strongest candidate for the association (p = 8.6 × 10−5, odds ratio = 1.58 with 95%CI 1.25-1.99). Suggestive signals were also obtained for three SNPs in the dihydropyrimidine dehydrogenase (DPYD) gene (rs6685859; p = 1.3 × 10−4, rs7550959; p = 1.5 × 10−4 and rs7531138; p = 1.7 × 10−4) and an intronic SNP, rs2269310, of the erythrocytic spectrin beta (SPTB) gene (p = 7.9 × 10−4).

BackgroundSystemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis and composed of two subtypes, limited and diffuse cutaneous forms. Previous genetic studies including genome-wide association studies (GWAS) have identified 12 susceptibility loci satisfying genome-wide significance.ObjectivesTo expand the list of susceptibility genes and deepen biological insights for SSc.MethodsWe performed trans-ethnic meta-analysis of GWAS in the Japanese and European populations, followed by a two-staged replication study comprising a total of 4,436 cases and 14,751 controls. Associations between significant single nuclear polymorphisms (SNPs) and neighboring genes were evaluated. Enrichment analysis of H3K4Me3, a representative histone mark for active promoter was conducted with an expanded list of SSc susceptibility genes.ResultsWe identified two significant SNP in two loci, GSDMA and PRDM1, both of which are related with immune functions and associated with other autoimmune diseases (p=1.4x10-10 and 6.6x10-10, respectively). GSDMA also showed a significant association with limited cutaneous SSc. We also replicated the associations of previously reported loci including a non-GWAS locus, TNFAIP3. PRDM1 encodes BLIMP1, a transcription factor regulating T cell proliferation and plasma cell differentiation. The top SNP in GSDMA was a missense variant and correlated with gene expression of neighboring genes, and this could explain the association in this locus. We found different HLA association patterns between the two populations or two subtypes. Enrichment analysis suggested the importance of CD4 naïve primary T cell.Conclusions GSDMA and PRDM1 are associated with SSc. These findings provide enhanced insight into the genetic and biological basis of SSc.Disclosure of InterestNone declared

Introduction Systemic sclerosis (SSc)-related pulmonary arterial hypertension (PAH) has emerged as a major mortality prognostic factor. Mutations of transforming growth factor beta (TGFβ) receptor genes strongly contribute to idiopathic and familial PAH. Objective To explore the genetic bases of SSc–PAH, we combined direct sequencing and genotyping of candidate genes encoding TGFβ receptor family members. Materials and methods TGFβ receptor genes, BMPR2, ALK1, TGFR2 and ENG, were sequenced in 10 SSc–PAH patients, nine SSc and seven controls. In addition, 22 single-nucleotide polymorphisms (SNP) of these four candidate genes were tested for association in a first set of 824 French Caucasian SSc patients (including 54 SSc–PAH) and 939 controls. The replication set consisted of 1516 European SSc (including 219 SSc–PAH) and 3129 controls from the European League Against Rheumatism Scleroderma Trials and Research group network. Results No mutation was identified by direct sequencing. However, two repertoried SNP, ENG rs35400405 and ALK1 rs2277382, were found in SSc–PAH patients only. The genotyping of 22 SNP including the latter showed that only rs2277382 was associated with SSc–PAH (p=0.0066, OR 2.13, 95% CI 1.24 to 3.65). Nevertheless, this was not replicated with the following result in combined analysis: p=0.123, OR 0.79, 95% CI 0.59 to 1.07. Conclusions This study demonstrates the lack of association between these TGFβ receptor gene polymorphisms and SSc–PAH using both sequencing and genotyping methods.

Introduction Systemic sclerosis (SSc)-related pulmonary arterial hypertension (PAH) has emerged as a major mortality prognostic factor. Mutations of transforming growth factor beta (TGFβ) receptor genes strongly contribute to idiopathic and familial PAH. Objective To explore the genetic bases of SScâ[euro]\"PAH, we combined direct sequencing and genotyping of candidate genes encoding TGFβ receptor family members. Materials and methods TGFβ receptor genes, BMPR2, ALK1 , TGFR2 and ENG , were sequenced in 10 SScâ[euro]\"PAH patients, nine SSc and seven controls. In addition, 22 single-nucleotide polymorphisms (SNP) of these four candidate genes were tested for association in a first set of 824 French Caucasian SSc patients (including 54 SScâ[euro]\"PAH) and 939 controls. The replication set consisted of 1516 European SSc (including 219 SScâ[euro]\"PAH) and 3129 controls from the European League Against Rheumatism Scleroderma Trials and Research group network. Results No mutation was identified by direct sequencing. However, two repertoried SNP, ENG rs35400405 and ALK1 rs2277382, were found in SScâ[euro]\"PAH patients only. The genotyping of 22 SNP including the latter showed that only rs2277382 was associated with SScâ[euro]\"PAH (p=0.0066, OR 2.13, 95% CI 1.24 to 3.65). Nevertheless, this was not replicated with the following result in combined analysis: p=0.123, OR 0.79, 95% CI 0.59 to 1.07. Conclusions This study demonstrates the lack of association between these TGFβ receptor gene polymorphisms and SScâ[euro]\"PAH using both sequencing and genotyping methods.

Rheumatoid arthritis (RA) is a common systemic autoimmune disease and its onset and prognosis are controlled by genetic, immunological, and environmental factors. The HLA locus, particularly HLA - DRB1 , is its strongest genetic risk determinant across ethnicities. Several other genes, including PTPN22 and PADI4 , show modest association with RA. However, they cover only a part of its genetic components and their relative contribution is different between populations. To identify novel genetic determinants, we took a candidate gene approach in a trans-ethnic manner. After critical selection of 169 genes based on their immunological function, we performed SNP discovery of these genes by the resequencing of exons and surrounding areas using European and Japanese DNAs. We then generated a panel of 1,509 SNPs for case–control association study in both populations. The DerSimonian–Laird test for meta-analysis, using the combined results of the two populations, identified rs7551957 at the 5′-flanking region of the low-affinity Fc-gamma receptor IIa ( FCGR2A ) gene as the strongest candidate for the association ( p  = 8.6 × 10 −5 , odds ratio = 1.58 with 95%CI 1.25–1.99). Suggestive signals were also obtained for three SNPs in the dihydropyrimidine dehydrogenase ( DPYD ) gene (rs6685859; p  = 1.3 × 10 −4 , rs7550959; p  = 1.5 × 10 −4 and rs7531138; p  = 1.7 × 10 −4 ) and an intronic SNP, rs2269310, of the erythrocytic spectrin beta ( SPTB ) gene ( p  = 7.9 × 10 −4 ).