| 1. |
- Harley, Isaac T. W., et al.
(author)
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The Role of Genetic Variation Near Interferon-Kappa in Systemic Lupus Erythematosus
- 2010
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In: Journal of Biomedicine and Biotechnology. - : Hindawi Limited. - 1110-7243 .- 1110-7251. ; , s. 706825-
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Journal article (peer-reviewed)abstract
- Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by increased type I interferons (IFNs) and multiorgan inflammation frequently targeting the skin. IFN-kappa is a type I IFN expressed in skin. A pooled genome-wide scan implicated the IFNK locus in SLE susceptibility. We studied IFNK single nucleotide polymorphisms (SNPs) in 3982 SLE cases and 4275 controls, composed of European (EA), African-American (AA), and Asian ancestry. rs12553951C was associated with SLE in EA males (odds ratio = 1.93, P = 2.5 x 10(-4)), but not females. Suggestive associations with skin phenotypes in EA and AA females were found, and these were also sex-specific. IFNK SNPs were associated with increased serum type I IFN in EA and AA SLE patients. Our data suggest a sex-dependent association between IFNK SNPs and SLE and skin phenotypes. The serum IFN association suggests that IFNK variants could influence type I IFN producing plasmacytoid dendritic cells in affected skin.
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| 2. |
- Lessard, Christopher J., et al.
(author)
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Identification of IRF8, TMEM39A, and IKZF3-ZPBP2 as Susceptibility Loci for Systemic Lupus Erythematosus in a Large-Scale Multiracial Replication Study
- 2012
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In: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 90:4, s. 648-660
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Journal article (peer-reviewed)abstract
- Systemic lupus erythematosus (SLE) is a chronic heterogeneous autoimmune disorder characterized by the loss of tolerance to self-antigens and dysregulated interferon responses. The etiology of SLE is complex, involving both heritable and environmental factors. Candidate-gene studies and genome-wide association (GWA) scans have been successful in identifying new loci that contribute to disease susceptibility; however, much of the heritable risk has yet to be identified. In this study, we sought to replicate 1,580 variants showing suggestive association with SLE in a previously published GWA scan of European Americans; we tested a multiethnic population consisting of 7,998 SLE cases and 7,492 controls of European, African American, Asian, Hispanic, Gullah, and Amerindian ancestry to find association with the disease. Several genes relevant to immunological pathways showed association with SLE. Three loci exceeded the genome-wide significance threshold: interferon regulatory factor 8 (IRF8; rs11644034; p(meta-Euro) = 2.08 x 10(-10)), transmembrane protein 39A (TMEM39A; rs1132200; p(meta-all) 8.62 x 10(-9)), and 17q21 (rs1453560; p(meta-all) = 3.48 x 10(-10)) between IKAROS family of zinc finger 3 (AIOLOS; IKZF3) and zona pellucida binding protein 2 (ZPBP2). Fine mapping, resequencing, imputation, and haplotype analysis of IRF8 indicated that three independent effects tagged by rs8046526, rs450443, and rs4843869, respectively, were required for risk in individuals of European ancestry. Eleven additional replicated effects (5 x 10(-8) < p(meta-Euro) < 9.99 x 10(-5)) were observed with CFHR1, CADM2, LOC730109/IL12A, LPP, LOC63920, SLU7, ADAMTSL1, C10orf64, OR8D4 FAM19A2, and STXBP6. The results of this study increase the number of confirmed SLE risk loci and identify others warranting further investigation.
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| 3. |
- Namjou, Bahram, et al.
(author)
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Evaluation of TRAF6 in a large multiancestral lupus cohort
- 2012
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In: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 64:6, s. 1960-1969
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Journal article (peer-reviewed)abstract
- Objective Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with significant immune system aberrations resulting from complex heritable genetics as well as environmental factors. We undertook to study the role of TRAF6 as a candidate gene for SLE, since it plays a major role in several signaling pathways that are important for immunity and organ development. Methods Fifteen single-nucleotide polymorphisms (SNPs) across TRAF6 were evaluated in 7,490 SLE patients and 6,780 control subjects from different ancestries. Population-based casecontrol association analyses and meta-analyses were performed. P values, false discovery rate q values, and odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated. Results Evidence of associations was detected in multiple SNPs. The best overall P values were obtained for SNPs rs5030437 and rs4755453 (P = 7.85 x 10(-5) and P = 4.73 x 10(-5), respectively) without significant heterogeneity among populations (P = 0.67 and P = 0.50, respectively, in Q statistic). In addition, SNP rs540386, which was previously reported to be associated with rheumatoid arthritis (RA), was found to be in linkage disequilibrium with these 2 SNPs (r2 = 0.95) and demonstrated evidence of association with SLE in the same direction (meta-analysis P = 9.15 x 10(-4), OR 0.89 [95% CI 0.830.95]). The presence of thrombocytopenia improved the overall results in different populations (meta-analysis P = 1.99 x 10(-6), OR 0.57 [95% CI 0.450.72], for rs5030470). Finally, evidence of family-based association in 34 African American pedigrees with the presence of thrombocytopenia was detected in 1 available SNP (rs5030437) with a Z score magnitude of 2.28 (P = 0.02) under a dominant model. Conclusion Our data indicate the presence of association of TRAF6 with SLE, consistent with the previous report of association with RA. These data provide further support for the involvement of TRAF6 in the pathogenesis of autoimmunity.
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| 4. |
- Adrianto, Indra, et al.
(author)
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Association of a functional variant downstream of TNFAIP3 with systemic lupus erythematosus
- 2011
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 43:3, s. 253-258
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Journal article (peer-reviewed)abstract
- Systemic lupus erythematosus (SLE, MIM152700) is an autoimmune disease characterized by self-reactive antibodies resulting in systemic inflammation and organ failure. TNFAIP3, encoding the ubiquitin-modifying enzyme A20, is an established susceptibility locus for SLE. By fine mapping and genomic re-sequencing in ethnically diverse populations, we fully characterized the TNFAIP3 risk haplotype and identified a TT>A polymorphic dinucleotide (deletion T followed by a T to A transversion) associated with SLE in subjects of European (P = 1.58 x 10(-8), odds ratio = 1.70) and Korean (P = 8.33 x 10(-10), odds ratio = 2.54) ancestry. This variant, located in a region of high conservation and regulatory potential, bound a nuclear protein complex composed of NF-kappa B subunits with reduced avidity. Further, compared with the non-risk haplotype, the haplotype carrying this variant resulted in reduced TNFAIP3 mRNA and A20 protein expression. These results establish this TT>A variant as the most likely functional polymorphism responsible for the association between TNFAIP3 and SLE.
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| 5. |
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| 6. |
- Castillejo-Lopez, Casimiro, et al.
(author)
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Genetic and physical interaction of the B-cell systemic lupus erythematosus-associated genes BANK1 and BLK
- 2012
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In: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 71:1, s. 136-142
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Journal article (peer-reviewed)abstract
- ObjectivesAltered signalling in B cells is a predominant feature of systemic lupus erythematosus (SLE). The genes BANK1 and BLK were recently described as associated with SLE. BANK1 codes for a B-cell-specific cytoplasmic protein involved in B-cell receptor signalling and BLK codes for an Src tyrosine kinase with important roles in B-cell development. To characterise the role of BANK1 and BLK in SLE, a genetic interaction analysis was performed hypothesising that genetic interactions could reveal functional pathways relevant to disease pathogenesis.MethodsThe GPAT16 method was used to analyse the gene-gene interactions of BANK1 and BLK. Confocal microscopy was used to investigate co-localisation, and immunoprecipitation was used to verify the physical interaction of BANK1 and BLK.ResultsEpistatic interactions between BANK1 and BLK polymorphisms associated with SLE were observed in a discovery set of 279 patients and 515 controls from northern Europe. A meta-analysis with 4399 European individuals confirmed the genetic interactions between BANK1 and BLK. As BANK1 was identified as a binding partner of the Src tyrosine kinase LYN, the possibility that BANK1 and BLK could also show a protein-protein interaction was tested. The co-immunoprecipitation and co-localisation of BLK and BANK1 were demonstrated. In a Daudi cell line and primary naive B cells endogenous binding was enhanced upon B-cell receptor stimulation using anti-IgM antibodies.ConclusionsThis study shows a genetic interaction between BANK1 and BLK, and demonstrates that these molecules interact physically. The results have important consequences for the understanding of SLE and other autoimmune diseases and identify a potential new signalling pathway.
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| 7. |
- Chung, Sharon A., et al.
(author)
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Differential Genetic Associations for Systemic Lupus Erythematosus Based on Anti-dsDNA Autoantibody Production
- 2011
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In: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 7:3, s. e1001323-
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Journal article (peer-reviewed)abstract
- Systemic lupus erythematosus (SLE) is a clinically heterogeneous, systemic autoimmune disease characterized by autoantibody formation. Previously published genome-wide association studies (GWAS) have investigated SLE as a single phenotype. Therefore, we conducted a GWAS to identify genetic factors associated with anti-dsDNA autoantibody production, a SLE-related autoantibody with diagnostic and clinical importance. Using two independent datasets, over 400,000 single nucleotide polymorphisms (SNPs) were studied in a total of 1,717 SLE cases and 4,813 healthy controls. Anti-dsDNA autoantibody positive (anti-dsDNA +, n = 811) and anti-dsDNA autoantibody negative (anti-dsDNA -, n = 906) SLE cases were compared to healthy controls and to each other to identify SNPs associated specifically with these SLE subtypes. SNPs in the previously identified SLE susceptibility loci STAT4, IRF5, ITGAM, and the major histocompatibility complex were strongly associated with anti-dsDNA + SLE. Far fewer and weaker associations were observed for anti-dsDNA - SLE. For example, rs7574865 in STAT4 had an OR for anti-dsDNA + SLE of 1.77 (95% CI 1.57-1.99, p = 2.0E-20) compared to an OR for anti-dsDNA - SLE of 1.26 (95% CI 1.12-1.41, p = 2.4E-04), with (Pheterogeneity)<0.0005. SNPs in the SLE susceptibility loci BANK1, KIAA1542, and UBE2L3 showed evidence of association with anti-dsDNA + SLE and were not associated with anti-dsDNA - SLE. In conclusion, we identified differential genetic associations with SLE based on anti-dsDNA autoantibody production. Many previously identified SLE susceptibility loci may confer disease risk through their role in autoantibody production and be more accurately described as autoantibody propensity loci. Lack of strong SNP associations may suggest that other types of genetic variation or non-genetic factors such as environmental exposures have a greater impact on susceptibility to anti-dsDNA - SLE.
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| 8. |
- Delgado Vega, Angélica María, 1982-
(author)
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Dissecting the Genetic Basis of Systemic Lupus Erythematosus : The Pursuit of Functional Variants
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Systemic lupus erythematosus (SLE) is a chronic and systemic autoimmune disease that primarily affects women during the childbearing years. SLE is characterized by the production of autoantibodies against nucleic acids and their interacting proteins. The exact molecular mechanisms leading to the breakdown of self-tolerance remain to a large extent unknown, but it is well established that they are influenced by both non-genetic (i.e. environmental and hormonal) and genetic factors. SLE is a complex, polygenic disease. Several susceptibility variants have been identified in SLE. However, the functional role in disease pathogenesis for the majority of them remains largely unknown.This thesis includes case-control association studies where the role of the genes TNFSF4 (Paper I), STAT4 (Paper II), CD226 (Paper III), and BLK (Papers IV and V) in the susceptibility of developing SLE was investigated. The primary focus was on the identification of the functional variants underlying the association. For each of these genes, fine mapping was performed using single nucleotide polymorphisms (SNPs), the linkage disequilibrium (LD) was characterized, and the association was narrowed down to specific haplotypes by means of several different statistical genetic strategies. Candidate variants were prioritized for further functional analysis on the basis of their potential effect on the gene function, their association, and/or biological plausibility. In Paper I, the association of TNFSF4 with SLE was validated and attributed to a risk haplotype tagged by SNPs rs1234317-T and rs12039904-T. Paper II provides evidence supporting the presence of at least two independent genetic effects within the STAT4 gene represented by rs3821236-A and rs7574865-A, which correlated with increased levels of gene expression. In Paper III, a functional allele in CD226 (rs727088-C) was identified, which was responsible for decreased levels in both mRNA and protein expression. In Paper IV, two independent genetic effects in the BLK gene were demonstrated. The first one comprised multiple regulatory variants in high LD that were enriched for NFκB and IRF4 binding sites and correlated with low BLK mRNA levels. The second was a low-frequency missense substitution (Ala71Thr) that decreased the BLK protein half-life. In Paper V, a genetic epistatic interaction between BANK1 rs10516487 (GG) and BLK rs2736340 (TT+TC) was demonstrated. Additional molecular analyses established that these molecules interact physically. These studies have contributed to the dissection of the genetic architecture of SLE. They highlight the allelic heterogeneity of the disease and provide functional links to the associated variants, which has significantly aided in the understanding of SLE disease pathogenesis.
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| 9. |
- Delgado-Vega, Angélica M., et al.
(author)
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Fine mapping and conditional analysis identify a new mutation in the autoimmunity susceptibility gene BLK that leads to reduced half-life of the BLK protein
- 2012
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In: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 71:7, s. 1219-1226
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Journal article (peer-reviewed)abstract
- ObjectivesTo perform fine mapping of the autoimmunity susceptibility gene BLK and identify functional variants involved in systemic lupus erythematosus (SLE).MethodsGenotyping of 1163 European SLE patients and 1482 controls and imputation were performed covering the BLK gene with 158 single-nucleotide polymorphisms. Logistic regression analysis was done using PLINK and conditional analyses using GENABEL's test score. Transfections of BLK constructs on HEK293 cells containing the novel mutation or the wild type form were analysed for their effect on protein half-life using a protein stability assay, cycloheximide and western blot. CHiP-qPCR for detection of nuclear factor. B (NFkB) binding.ResultsFine mapping of BLK identified two independent genetic effects with functional consequences: one represented by two tightly linked associated haplotype blocks significantly enriched for NF kappa B-binding sites and numerous putative regulatory variants whose risk alleles correlated with low BLK mRNA levels. Binding of NFkBp50 and p65 to an associated 1.2 Kb haplotype segment was confirmed. A second independent genetic effect was represented by an Ala71Thr, low-frequency missense substitution with an OR = 2.31 (95% CI 1.38 to 3.86). The 71Thr decreased BLK protein half-life.ConclusionsThese results show that rare and common regulatory variants in BLK are involved in disease susceptibility and both, albeit independently, lead to reduced levels of BLK protein.
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| 10. |
- Delgado-Vega, Angelica M., et al.
(author)
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Genetic associations in type I interferon related pathways with autoimmunity
- 2010
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In: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6354 .- 1478-6362. ; 12, s. S2-
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Research review (peer-reviewed)abstract
- Type I interferons play an outstanding role in innate and adaptive immunity by enhancing functions of dendritic cells, inducing differentiation of monocytes, promoting immunoglobulin class switching in B cells and stimulating effector functions of T cells. The increased production of IFN alpha/beta by plasmacytoid dendritic cells could be responsible for not only efficient antiviral defence, but it also may be a pathological factor in the development of various autoimmune disorders. The first evidence of a genetic link between type I interferons and autoimmune diseases was the observation that elevated IFN alpha activity is frequently detected in the sera of patients with systemic lupus erythematosus, and that this trait shows high heritability and familial aggregation in their first-degree healthy relatives. To date, a number of genes involved in interferon signalling have been associated with various autoimmune diseases. Patients with systemic lupus erythematosus, Sjogren's syndrome, dermatomyositis, psoriasis, and a fraction of patients with rheumatoid arthritis display a specific expression pattern of interferon-dependent genes in their leukocytes, termed the interferon signature. Here, in an attempt to understand the role of type I interferons in the pathogenesis of autoimmunity, we review the recent advances in the genetics of autoimmune diseases focusing on the association of genes involved in type I interferon pathways.
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