The grey line representsP=0

The grey line representsP=0.05, and the black lineP=0.01. To increase power, we designed a panel of SNPs in the IKBKE, TANK, STAT1, IL8, NRP1, TRAF6 and PIAS4 genes for genotyping in an independent collection of Swedish SLE patients and controls. SNPs in theIKBKE, TANK, STAT1, IL8andTRAF6genes gave nominal signals of association with SLE in this extended Swedish cohort. To replicate these findings we extracted data from a genomewide association study on SLE performed in a US cohort. Combined analysis of the Swedish and US data, comprising a total of 2136 cases and 9694 controls, implicatesIKBKEandIL8as SLE susceptibility loci (Pmeta=0.00010 andPmeta=0.00040, respectively).STAT1was also associated with SLE in this cohort (Pmeta=3.3 105), but this association signal appears to be dependent of that previously reported for the neighbouringSTAT4gene. Our study suggests additional genes from the type I interferon system in Atracurium besylate SLE, and highlights genes in this pathway for further functional analysis. Keywords:systemic lupus erythematosus, type I interferon system, candidate gene study, single nucleotide polymorphism, IKBKE, IL8 == Introduction == Systemic Lupus Erythematosus (SLE, OMIM 152700) is an inflammatory autoimmune disease that primarily affects women during their childbearing years. Production of autoantibodies, tissue deposits of immune complexes and inflammation in kidneys, skin, joints and central nervous system are hallmarks of SLE. Despite a strong heritability of the disease, linkage studies have failed to identify genes outside the major histocompatibility complex (MHC) region as risk factors for SLE. Association studies have since Atracurium besylate proven a more fruitful approach. The confirmed findings from genomewide association studies (GWAS) include genes that were originally discovered in candidate gene studies, such as the interferon regulatory factor 5 (IRF5)1and the signal transducer and activator of transcription 4 (STAT4)2genes from the type I IFN system. IFNs are cytokines with antiviral activity that are produced in response to viral infections, of which the type I IFNs bind the IFN- receptor (IFNAR). Today there are more than 20 confirmed SLE susceptibility loci,3,4of which several are in the type I IFN system. The type I IFN system is activated in SLE patients,5,6and an important role of the type I IFN system in the disease process was confirmed by studies showing an increased expression of type I IFN-inducible genes in SLE patients (an IFN-signature’).7A direct causative role of the type I IFN system in the etiopathogenesis of SLE was suggested by the observation that individuals treated with IFN-can develop an SLE syndrome indistinguishable from the naturally occurring disease.8Moreover, a phase I clinical trial with a monoclonal antibody against IFN-, reports reduction of disease activity as well as neutralization of the IFN signature in SLE Atracurium besylate patients.9,10Encouraged by the compelling evidence for the involvement of Atracurium besylate the type I IFN system in SLE, we performed an association study to identify additional genes from the type I IFN pathway that confer risk for SLE. == Materials and methods == == Subjects and genotyping == Our study included 826 Swedish and 1310 US SLE patients, fulfilling at least four of the classification criteria for SLE as defined by the American College of Rheumatology (ACR),11and 9694 healthy control individuals from the same geographic areas as the patients (Supplementary Table S1). DNA was extracted from blood samples of the patients and controls using standard procedures. The study was approved by the regional ethical boards and all subjects gave their informed consent to participate. The study was performed in three stages: == Discovery phase == First, a panel of SNPs in 82 genes with key functions related to the type I IFN signalling system and 14 additional genes, with suggested association with SLE, were selected for genotyping in 490 Swedish SLE patients and 543 controls. Patients were from the rheumatology clinics at the Lund, Karolinska (Solna) and Uppsala University Hospitals in Sweden. SNPs were selected on the basis of their average spacing of around 1 kb and LD information from the HapMap project (r2<0.8 HapMap CEU release 16c), excluding SNPs with an Illumina quality score <0.6. Genotyping of 1258 SNPs in the 96 genes was performed using the Golden Gate Assay (Illumina Inc., San Diego, CA, USA). Samples and SNPs with >10% missing data, SNPs with HardyWeinberg equilibrium testP-values <0.001 and SNPs with MAF <0.01 were excluded from further analysis. Four parentoffspring trios were included in the genotyping for inheritance checks, and no Mendelian inheritance errors were observed. After exclusion of genetic outliers, duplicate or related INMT antibody samples 482 cases, 536 controls and 896 SNPs in 92 genes were available for analysis. == Confirmatory set == In the second phase,.