Association of IRF5 in UK SLE families identifies a variant involved in polyadenylation.
ABSTRACT: Results from two studies have implicated the interferon regulatory gene IRF5 as a susceptibility gene in systemic lupus erythematosus (SLE). In this study, we conducted a family-based association analysis in 380 UK SLE nuclear families. Using a higher density of markers than has hitherto been screened, we show that there is association with two SNPs in the first intron, rs2004640 (P = 3.4 x 10(-4)) and rs3807306 (P = 4.9 x 10(-4)), and the association extends into the 3'-untranslated region (UTR). There is a single haplotype block encompassing IRF5 and we show for the first time that the gene comprises two over-transmitted haplotypes and a single under-transmitted haplotype. The strongest association is with a TCTAACT haplotype (T:U = 1.92, P = 5.8 x 10(-5)), which carries all the over-transmitted alleles from this study. Haplotypes carrying the T alleles of rs2004640 and rs2280714 and the A allele of rs10954213 are over-transmitted in SLE families. The TAT haplotype shows a dose-dependent relationship with mRNA expression. A differential expression pattern was seen between two expression probes located each side of rs10954213 in the 3'-UTR. rs10954213 shows the strongest association with RNA expression levels (P = 1 x 10(-14)). The A allele of rs10954213 creates a functional polyadenylation site and the A genotype correlates with increased expression of a transcript variant containing a shorter 3'-UTR. Expression levels of transcript variants with the shorter or longer 3'-UTRs are inversely correlated. Our data support a new mechanism by which an IRF5 polymorphism controls the expression of alternate transcript variants which may have different effects on interferon signalling.
Project description:Genetic variants of the interferon (IFN) regulatory factor 5 gene (IRF5) are associated with susceptibility to systemic lupus erythematosus (SLE). The contribution of these variants to IRF-5 expression in primary blood cells of SLE patients has not been addressed, nor has the role of type I IFNs. The aim of this study was to determine the association between increased IRF-5 expression and the IRF5 risk haplotype in SLE patients.IRF-5 transcript and protein levels in 44 Swedish patients with SLE and 16 healthy controls were measured by quantitative real-time polymerase chain reaction, minigene assay, and flow cytometry. Single-nucleotide polymorphisms rs2004640, rs10954213, and rs10488631 and the CGGGG insertion/deletion were genotyped in these patients. Genotypes of these polymorphisms defined both a common risk haplotype and a common protective haplotype.IRF-5 expression and alternative splicing were significantly up-regulated in SLE patients compared with healthy donors. Enhanced transcript and protein levels were associated with the risk haplotype of IRF5; rs10488631 displayed the only significant independent association that correlated with increased transcription from the noncoding first exon 1C. Minigene experiments demonstrated an important role for rs2004640 and the CGGGG insertion/deletion, along with type I IFNs, in regulating IRF5 expression.This study provides the first formal proof that IRF-5 expression and alternative splicing are significantly up-regulated in primary blood cells of patients with SLE. Furthermore, the risk haplotype is associated with enhanced IRF-5 transcript and protein expression in patients with SLE.
Project description:OBJECTIVE: Interferon regulatory factor 5 (IRF-5) is a transcription factor involved in the regulation of the host defense. Previous studies have demonstrated a significant association of various IRF5 gene polymorphisms with systemic lupus erythematosus (SLE) in Caucasians. The purpose of this case-control study was to investigate whether IRF5 polymorphisms are involved in the genetic predisposition to primary Sjögren's syndrome (SS), an autoimmune disease closely related to SLE. METHODS: We analyzed IRF5 rs2004640, rs2070197, rs10954213, and rs2280714 polymorphisms in a cohort of 212 primary SS patients and 162 healthy blood donors, all of whom were of Caucasian origin. The 4 polymorphisms examined were genotyped by competitive allele-specific polymerase chain reaction using fluorescence resonance energy transfer technology. RESULTS: The IRF5 rs2004640 GT or TT genotype (T allele carriers) was identified in 87% of primary SS patients compared with 77% of controls (P = 0.01, odds ratio [OR] 1.93 [95% confidence interval (95% CI) 1.15-3.42]). The IRF5 rs2004640 T allele was found on 59% of chromosomes from primary SS patients compared with 52% of chromosomes from controls (P = 0.04, OR 1.36 [95% CI 1.01-1.83]). No significant association of primary SS with rs2070197, rs10954213, or rs2280714 was seen when they were analyzed independently. Nevertheless, haplotype reconstructions based on the 4 polymorphisms examined suggest that various allele combinations of rs2004640 and rs2070197 could define susceptibility or protective haplotypes. CONCLUSION: This study is the first to demonstrate a significant association between primary SS and the IRF5 rs2004640 T allele. These results, which require further replication on larger populations, suggest that besides their association with identical major histocompatibility complex gene polymorphisms, primary SS and SLE share IRF gene polymorphisms as a common genetic susceptibility factor.
Project description:OBJECTIVE:Interferon (IFN) signaling plays a crucial role in autoimmunity. Genetic variation in interferon regulatory factor 5 (IRF5), a major regulator of the type I interferon induction, has been associated with risk of developing several autoimmune diseases. In the current study we aimed to evaluate whether three sets of correlated IRF5 genetic variants, independently associated with SLE and with different functional roles, are involved in uveitis susceptibility and its clinical subphenotypes. METHODS:Three IRF5 polymorphisms, rs2004640, rs2070197 and rs10954213, representative of each group, were genotyped using TaqMan® allelic discrimination assays in a total of 263 non-anterior uveitis patients and 724 healthy controls of Spanish origin. RESULTS:A clear association between two of the three analyzed genetic variants, rs2004640 and rs10954213, and the absence of macular edema was observed in the case/control analysis (P FDR =5.07E-03, OR=1.48, CI 95%=1.14-1.92 and P FDR =3.37E-03, OR=1.54, CI 95%=1.19-2.01, respectively). Consistently, the subphenotype analysis accordingly with the presence/absence of this clinical condition also reached statistical significance (rs2004640: P=0.037, OR=0.69, CI 95%=0.48-0.98; rs10954213: P=0.030, OR=0.67, CI 95%=0.47-0.96), thus suggesting that both IRF5 genetic variants are specifically associated with the lack of macular edema in uveitis patients. CONCLUSION:Our results clearly showed for the first time that two functional genetic variants of IRF5 may play a role in the development of macular edema in non-anterior uveitis patients. Identifying genetic markers for macular edema could lead to the possibility of developing novel treatments or preventive therapies.
Project description:Background & objectives:Genetic aberrations disrupting toll-like receptor and interferon homeostasis enhance the risk of systemic lupus erythematosus (SLE). Raised serum interferon-alpha (IFN-?) levels in SLE patients have been ascribed to polymorphism (rs2004640 G/T) in interferon regulatory factor 5 (IRF5) gene, resulting in enhanced transcript splicing. A positive association between IRF5 polymorphism and SLE risk has been reported in many populations. This study was aimed to find out frequency of IRF5 rs2004640 G/T polymorphism in patients with SLE and healthy controls and to assess its influence on susceptibility, clinical and serological characteristics of SLE. Methods:IRF5 rs2004640 (G/T) polymorphism was analyzed in 300 SLE patients and 460 age and sex matched controls by real-time PCR. Results:The IRF5 rs2004640 (G/T) polymorphism did not confer risk of SLE or influence clinical or serological phenotype. However, the mutant allele conferred a borderline risk to develop thrombocytopenia (odds ratio: 2.05, 95% confidence interval: 0.97-4.3, P=0.06) in patients with SLE. Interpretation & conclusions:Our study revealed that the IRF5 rs2004640 polymorphism was not a risk factor for SLE in population from south India. It may, however, be a useful genetic marker for thrombocytopenia in SLE patients. Although we could not demonstrate susceptibility toward lupus in the presence of IRF5 rs2004640 (G/T) polymorphism, further exploration of the genetic variability of IRF5 may help uncover its pathogenic role in Indian SLE patients.
Project description:INTRODUCTION: Rheumatoid arthritis (RA) is a complex polygenic inflammatory disease associated with accelerated atherosclerosis and increased cardiovascular (CV) disease risk. Interferon regulatory factor 5 (IRF5) is a regulator of type I interferon induction. Recently, researchers have described an association between multiple single-nucleotide polymorphisms of the IRF5 gene and some rheumatic disorders. In this study, we aimed to evaluate whether three different haplotype blocks within the IRF5 locus which have been shown to alter the protein function are involved in the risk of CV events occurring in Spanish RA patients. METHODS: Three IRF5 polymorphisms (rs2004640, rs2070197 and rs10954213) representative of each haplotype group were genotyped by performing TaqMan assays using a 7900HT Fast Real-Time PCR System with tissue from a total of 2,137 Spanish patients diagnosed with RA. Among them, 390 (18.2%) had experienced CV events. The relationship of IRF5 genotypes and haplotypes to CV events was tested using Cox regression. RESULTS: Male sex, age at RA diagnosis and most traditional risk factors (hypertension, dyslipidemia and smoking habit) were associated with increased risk for CV events in the RA population. Interestingly, a protective effect of both IRF5 rs2004640 GG and IRF5 rs10954213 GG genotypes against the risk for CV events after adjusting the results for sex, age at RA diagnosis and traditional CV disease risk factors was observed (hazard ratio (HR) = 0.6, 95% confidence interval (CI) = 0.38 to 0.92, P = 0.02; and HR = 0.58, 95% CI = 0.36 to 0.95, P = 0.03, respectively). Moreover, we detected a protective effect of the GTG haplotype against the risk for CV events after adjusting the results for potential confounding factors (HR = 0.72, 95% CI = 0.56 to 0.93, P = 0.012). CONCLUSIONS: Our results reveal that IRF5 gene variants are associated with risk of CV events in patients with RA.
Project description:BACKGROUND The IRF5 and TYK2 gene polymorphisms are associated with autoimmune diseases. However, the relationship between the IRF5 and TYK2 gene polymorphisms and RA risk in the Chinese Han population was inconsistent. MATERIAL AND METHODS A total of 578 RA patients (case group) and 578 healthy controls (control group) were assessed in a case-control study. Genotyping of IRF5 (Exon 6 insertion/deletion (in/de), rs2004640, rs2070197, rs10954213) and TYK2 (rs280500, rs280519, rs280521, rs8108236, rs12720253) was performed by direct sequencing method. Data analysis was performed by SHEsis. RESULTS The rs2004640T allele (P=0.0003) and the dominant (P=0.001) and recessive (P=0.01) models of rs2004640 were associated with RA risk after stringent Bonferroni correction (0.05/4). The IRF5 exon 6 (in), rs2070197 and rs10954213 were not associated with RA (P>0.05). Two haplotypes of IRF5 (DTAT and DTGG) were associated with RA susceptibility (P<0.05). In addition, the frequencies of TYK2 rs280500A, rs280521A, and rs8108236A were significantly higher in the RA group compared with the control group (P<0.05). TYK2 rs280500, rs280521, and rs8108236 were associated with RA susceptibility in the dominant model, but the same was not observed for rs280519 and rs12720253 (P<0.05). Furthermore, 3 risk haplotypes (AAAGT, AGGAT, and GAAAT) and a protective haplotype (GAGGT) of TYK2 gene were associated with RA susceptibility (P<0.05). CONCLUSIONS Our results suggest that IRF5 rs2004640, TYK2 rs280500, rs280521, rs8108236, and haplotypes IRF5 (DTAT and DTGG) and TYK2 (AAAGT, AGGAT, GAAAT, and GAGGT) are susceptible factors for RA in a Chinese Han population.
Project description:Recently, two studies provided convincing evidence that IFN regulatory factor 5 (IRF5) gene polymorphisms are significantly associated with systemic lupus erythematosus (SLE) in several white populations. To replicate the association with SLE in an Asian population, we examined the genetic effects in our SLE cohort from a Korean population. A total of 1,565 subjects, composed of 593 cases and 972 controls, were genotyped using the TaqMan (Applied Biosystems, Foster City, CA, USA) method. The genetic effects of polymorphisms on the risk of SLE were evaluated using chi2 tests and a Mantel-Haenszel meta-analysis. Statistical analysis revealed results in the Korean population were similar to the previous reports from white populations. The rs2004640 T allele had a higher frequency in SLE cases (0.385) than controls (0.321; odds ratio (OR) = 1.32, P = 0.0003). In combined analysis, including all seven independent cohorts from the three studies so far, robust and consistent associations of the rs2004640 T allele with SLE were observed. The estimate of risk was OR = 1.44 (range, 1.34-1.55), with an overall P = 1.85 x 10(-23) for the rs2004640 T allele. The haplotype (rs2004640T-rs2280714T) involved in both the alternative splice donor site and the elevated expression of IRF5 also had a highly significant association with SLE (pooled, P = 2.11 x 10(-16)). Our results indicate that the genetic effect on the risk of SLE mediated by IRF5 variants can be generally accepted in both white and Asian populations.
Project description:BACKGROUND: Recently, a new genetic factor within the interferon regulatory factor 5 (IRF5) gene was demonstrated for systemic lupus erythematosus (SLE) through linkage and association: the rs2004640-T allele. IRF5 is involved in the production of rheumatoid arthritis (RA) cytokines, and SLE already shares with RA one genetic factor within the tyrosine phosphatase PTPN22 gene. AIM: To test the hypothesis that the SLE IRF5 genetic factor could also be shared with RA. PATIENTS AND METHODS: 100 French Caucasian trio families with RA were genotyped and analysed with the transmission disequilibrium test, the frequency comparison of the transmitted and untransmitted alleles, and the genotype relative risk. 97% power was available to detect at least a trend in favour of a factor similar to that reported for SLE. RESULTS: The analysis showed the absence of linkage and association globally and in "autoimmune" RA subsets, with a weak non-significant trend against the IRF5 rs20046470-T allele. Given the robustness of familial-based analysis, this slight negative trend provided strong evidence against even a weaker factor than that reported for SLE. CONCLUSION: Our results exclude the IRF5 rs2004640-T allele as a major genetic factor for RA in this French Caucasian population.
Project description:INTRODUCTION: Interferon regulatory factor 5 gene (IRF5) polymorphisms are strongly associated with several diseases, including systemic lupus erythematosus (SLE). The association includes risk and protective components. They could be due to combinations of functional polymorphisms and related to cis-regulation of IRF5 expression, but their mechanisms are still uncertain. We hypothesised that thorough testing of the relationships between IRF5 polymorphisms, expression data from multiple experiments and SLE-associated haplotypes might provide useful new information. METHODS: Expression data from four published microarray hybridisation experiments with lymphoblastoid cell lines (57 to 181 cell lines) were retrieved. Genotypes of 109 IRF5 polymorphisms, including four known functional polymorphisms, were considered. The best linear regression models accounting for the IRF5 expression data were selected by using a forward entry procedure. SLE-associated IRF5 haplotypes were correlated with the expression data and with the best cis-regulatory models. RESULTS: A large fraction of variability in IRF5 expression was accounted for by linear regression models with IRF5 polymorphisms, but at a different level in each expression data set. Also, the best models from each expression data set were different, although there was overlap between them. The SNP introducing an early polyadenylation signal, rs10954213, was included in the best models for two of the expression data sets and in good models for the other two data sets. The SLE risk haplotype was associated with high IRF5 expression in the four expression data sets. However, there was also a trend towards high IRF5 expression with some protective and neutral haplotypes, and the protective haplotypes were not associated with IRF5 expression. As a consequence, correlation between the cis-regulatory best models and SLE-associated haplotypes, regarding either the risk or protective component, was poor. CONCLUSIONS: Our analysis indicates that although the SLE risk haplotype of IRF5 is associated with high expression of the gene, cis-regulation of IRF5 expression is not enough to fully account for IRF5 association with SLE susceptibility, which indicates the need to identify additional functional changes in this gene.
Project description: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(-8), OR ?=?1.22, CI 95% ?=?1.14-1.30; rs2004640: P ?=?4.60×10(-7), OR ?=?0.84, CI 95% ?=?0.78-0.90; rs10488631: P ?=?7.53×10(-20), 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(-22), OR ?=?1.75, CI 95% ?=?1.56-1.97) better explained the observed association (likelihood P-value ?=?1.48×10(-4)), 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.