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1.  Molecular basis of an autoantibody-associated restriction fragment length polymorphism that confers susceptibility to autoimmune diseases. 
Journal of Clinical Investigation  1991;88(1):193-203.
Recently, combined serological and molecular studies of autoantibodies have revealed that these antibodies play an important role in the normal function of the immune system and in the development of the B cell repertoire. Accordingly, we hypothesized that a homozygous deletion of a critical autoantibody-associated Ig variable (V) gene may alter the immune system and thus predispose the host to autoimmune disorders. Initial experiments revealed several restriction fragment length polymorphisms (RFLP) of the Humhv3005 gene, that is likely to encode heavy chains of rheumatoid factors, and the closely related 1.9III gene. By probing EcoR1-digested DNA with the Humhv3005/P1 probe, we found that one of the four major hybridizing bands was missing in approximately 20% of patients with either rheumatoid arthritis or systemic lupus erythematosus, but only 2% of normal subjects. To delineate the genetic basis of this polymorphism, we have now employed the PCR to amplify and analyze hv3005, 1.9III, and homologous genes in individuals with characteristic RFLP genotypes. Our results indicate that the human Vh gene repertoire contains several hv3005- and 1.9III-like genes, and that a complete deletion of the hv3005-like genes is relatively restricted to a subset of autoimmune patients. These findings provide initial evidence for deletion of developmentally regulated autoreactive V genes in autoimmune diseases.
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PMCID: PMC296020  PMID: 1676037
2.  A Functional Variant in MicroRNA-146a Promoter Modulates Its Expression and Confers Disease Risk for Systemic Lupus Erythematosus 
PLoS Genetics  2011;7(6):e1002128.
Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic predisposition, characterized by an upregulated type I interferon pathway. MicroRNAs are important regulators of immune homeostasis, and aberrant microRNA expression has been demonstrated in patients with autoimmune diseases. We recently identified miR-146a as a negative regulator of the interferon pathway and linked the abnormal activation of this pathway to the underexpression of miR-146a in SLE patients. To explore why the expression of miR-146a is reduced in SLE patients, we conducted short parallel sequencing of potentially regulatory regions of miR-146a and identified a novel genetic variant (rs57095329) in the promoter region exhibiting evidence for association with SLE that was replicated independently in 7,182 Asians (Pmeta = 2.74×10−8, odds ratio = 1.29 [1.18–1.40]). The risk-associated G allele was linked to reduced expression of miR-146a in the peripheral blood leukocytes of the controls. Combined functional assays showed that the risk-associated G allele reduced the protein-binding affinity and activity of the promoter compared with those of the promoter containing the protective A allele. Transcription factor Ets-1, encoded by the lupus-susceptibility gene ETS1, identified in recent genome-wide association studies, binds near this variant. The manipulation of Ets-1 levels strongly affected miR-146a promoter activity in vitro; and the knockdown of Ets-1, mimicking its reduced expression in SLE, directly impaired the induction of miR-146a. We also observed additive effects of the risk alleles of miR-146a and ETS1. Our data identified and confirmed an association between a functional promoter variant of miR-146a and SLE. This risk allele had decreased binding to transcription factor Ets-1, contributing to reduced levels of miR-146a in SLE patients.
Author Summary
Genome-wide association studies have identified quite a number of susceptibility loci associated with complex diseases such as systemic lupus erythematosus (SLE). However, for most of them, the intrinsic link between genetic variation and disease mechanism is not fully understood. SLE is characterized by a significantly upregulated type I interferon (IFN) pathway, and we have previously reported that underexpression of a microRNA, miR-146a, contributes to alterations in the type I IFN pathway in lupus patients. Here we identified a novel genetic variant in the promoter region of miR-146a that is directly related to reduced expression of miR-146a and is associated with SLE susceptibility. The risk allele of this variant confers weaker binding affinity for Ets-1, which is a transcription factor encoded by a lupus susceptibility gene found in recent GWAS. These findings suggest that reduced expression of Ets-1 and its reduced binding affinity to the miR-146a promoter both may contribute to low levels of this microRNA in SLE patients, which may contribute to the upregulated type I IFN pathway in these patients. To our knowledge, this is also the first piece of evidence showing association between a genetic variant in a promoter region of a miRNA gene and a human disease.
doi:10.1371/journal.pgen.1002128
PMCID: PMC3128113  PMID: 21738483
3.  A Comprehensive Analysis of Shared Loci between Systemic Lupus Erythematosus (SLE) and Sixteen Autoimmune Diseases Reveals Limited Genetic Overlap 
PLoS Genetics  2011;7(12):e1002406.
In spite of the well-known clustering of multiple autoimmune disorders in families, analyses of specific shared genes and polymorphisms between systemic lupus erythematosus (SLE) and other autoimmune diseases (ADs) have been limited. Therefore, we comprehensively tested autoimmune variants for association with SLE, aiming to identify pleiotropic genetic associations between these diseases. We compiled a list of 446 non–Major Histocompatibility Complex (MHC) variants identified in genome-wide association studies (GWAS) of populations of European ancestry across 17 ADs. We then tested these variants in our combined Caucasian SLE cohorts of 1,500 cases and 5,706 controls. We tested a subset of these polymorphisms in an independent Caucasian replication cohort of 2,085 SLE cases and 2,854 controls, allowing the computation of a meta-analysis between all cohorts. We have uncovered novel shared SLE loci that passed multiple comparisons adjustment, including the VTCN1 (rs12046117, P = 2.02×10−06) region. We observed that the loci shared among the most ADs include IL23R, OLIG3/TNFAIP3, and IL2RA. Given the lack of a universal autoimmune risk locus outside of the MHC and variable specificities for different diseases, our data suggests partial pleiotropy among ADs. Hierarchical clustering of ADs suggested that the most genetically related ADs appear to be type 1 diabetes with rheumatoid arthritis and Crohn's disease with ulcerative colitis. These findings support a relatively distinct genetic susceptibility for SLE. For many of the shared GWAS autoimmune loci, we found no evidence for association with SLE, including IL23R. Also, several established SLE loci are apparently not associated with other ADs, including the ITGAM-ITGAX and TNFSF4 regions. This study represents the most comprehensive evaluation of shared autoimmune loci to date, supports a relatively distinct non–MHC genetic susceptibility for SLE, provides further evidence for previously and newly identified shared genes in SLE, and highlights the value of studies of potentially pleiotropic genes in autoimmune diseases.
Author Summary
It is well known that multiple autoimmune disorders cluster in families. However, all of the genetic variants that explain this clustering have not been discovered, and the specific genetic variants shared between systemic lupus erythematosus (SLE) and other autoimmune diseases (ADs) are not known. In order to better understand the genetic factors that explain this predisposition to autoimmunity, we performed a comprehensive evaluation of shared autoimmune genetic variants. First we considered results from 17 ADs and compiled a list with 446 significant genetic variants from these studies. We identified some genetic variants extensively shared between ADs, as well as the ADs that share the most variants. The genetic overlap between SLE and other ADs was modest. Next we tested how important all the 446 genetic variants were in our collection with a minimum of 1,500 SLE patients. Among the most significant variants in SLE, the majority had already been identified in previous studies, but we also discovered variants in two important immune genes. In summary, our data identified diseases with common genetic risk factors and novel SLE effects, and this supports a relatively distinct genetic susceptibility for SLE. This study helps delineate the genetic architecture of ADs.
doi:10.1371/journal.pgen.1002406
PMCID: PMC3234215  PMID: 22174698
4.  Interferon Regulatory Factors in Human Lupus Pathogenesis 
Systemic lupus erythematosus (SLE) is a severe multi-system autoimmune disease which results from both genetic predisposition and environmental factors. Many lines of investigation support interferon alpha (IFN-α) as a causal agent in human lupus, and high levels of serum IFN-α are a heritable risk factor for SLE. Interferon regulatory factors (IRFs) are a family of transcription factors involved in host defense, which can induce transcription of IFN-α and other immune response genes following activation. In SLE, circulating immune complexes which contain nucleic acid are prevalent. These complexes are recognized by endosomal Toll-like receptors, resulting in activation of downstream IRF proteins. Genetic variants in the IRF5 and IRF7 genes have been associated with SLE susceptibility, and these same variants are associated with increased serum IFN-α in SLE patients. The increase in serum IFN-α related to IRF5 and 7 genotypes is observed only in patients with particular antibody specificities. This suggests that chronic stimulation of the endosomal Toll-like receptors by autoantibody immune complexes is required for IRF SLE-risk variants to cause elevation of circulating IFN-α and subsequent risk of SLE. Recently, genetic variation in the IRF8 gene has been associated with SLE and multiple sclerosis, and studies support an impact of IRF8 genotype on the IFN-α pathway. In summary, the SLE-associated polymorphisms in the IRF family of proteins appear to be gain-of-function variants, and understanding the impact of these variants upon the IFN-α pathway in vivo may guide therapeutic strategies directed at the Toll-like receptor/IRF/IFN-α pathway in SLE.
doi:10.1016/j.trsl.2011.01.006
PMCID: PMC3096827  PMID: 21575916
Interferon Alpha; Genetics; Systemic Lupus Erythematosus; Interferon Regulatory Factor; Autoantibodies; Autoimmunity
5.  Specificity of the STAT4 Genetic Association for Severe Disease Manifestations of Systemic Lupus Erythematosus 
PLoS Genetics  2008;4(5):e1000084.
Systemic lupus erythematosus (SLE) is a genetically complex disease with heterogeneous clinical manifestations. A polymorphism in the STAT4 gene has recently been established as a risk factor for SLE, but the relationship with specific SLE subphenotypes has not been studied. We studied 137 SNPs in the STAT4 region genotyped in 4 independent SLE case series (total n = 1398) and 2560 healthy controls, along with clinical data for the cases. Using conditional testing, we confirmed the most significant STAT4 haplotype for SLE risk. We then studied a SNP marking this haplotype for association with specific SLE subphenotypes, including autoantibody production, nephritis, arthritis, mucocutaneous manifestations, and age at diagnosis. To prevent possible type-I errors from population stratification, we reanalyzed the data using a subset of subjects determined to be most homogeneous based on principal components analysis of genome-wide data. We confirmed that four SNPs in very high LD (r2 = 0.94 to 0.99) were most strongly associated with SLE, and there was no compelling evidence for additional SLE risk loci in the STAT4 region. SNP rs7574865 marking this haplotype had a minor allele frequency (MAF) = 31.1% in SLE cases compared with 22.5% in controls (OR = 1.56, p = 10−16). This SNP was more strongly associated with SLE characterized by double-stranded DNA autoantibodies (MAF = 35.1%, OR = 1.86, p<10−19), nephritis (MAF = 34.3%, OR = 1.80, p<10−11), and age at diagnosis<30 years (MAF = 33.8%, OR = 1.77, p<10−13). An association with severe nephritis was even more striking (MAF = 39.2%, OR = 2.35, p<10−4 in the homogeneous subset of subjects). In contrast, STAT4 was less strongly associated with oral ulcers, a manifestation associated with milder disease. We conclude that this common polymorphism of STAT4 contributes to the phenotypic heterogeneity of SLE, predisposing specifically to more severe disease.
Author Summary
Systemic lupus erythematosus is a chronic disabling autoimmune disease, most commonly striking women in their thirties or forties. It can cause a wide variety of clinical manifestations, including kidney disease, arthritis, and skin disorders. Prognosis varies greatly depending on these clinical features, with kidney disease and related characteristics leading to greater morbidity and mortality. It is also complex genetically; while lupus runs in families, genes increase one’s risk for lupus but do not fully determine the outcome. It is thought that the interactions of multiple genes and/or interactions between genes and environmental factors may cause lupus, but the causes and disease pathways of this very heterogeneous disease are not well understood. By examining relationships between subtypes of lupus and specific genes, we hope to better understand how lupus is triggered and by what biological pathways it progresses. We show in this work that the STAT4 gene, very recently identified as a lupus risk gene, predisposes specifically to severe manifestations of lupus, including kidney disease.
doi:10.1371/journal.pgen.1000084
PMCID: PMC2377340  PMID: 18516230
6.  Identification of Two Independent Risk Factors for Lupus within the MHC in United Kingdom Families 
PLoS Genetics  2007;3(11):e192.
The association of the major histocompatibility complex (MHC) with SLE is well established yet the causal variants arising from this region remain to be identified, largely due to inadequate study design and the strong linkage disequilibrium demonstrated by genes across this locus. The majority of studies thus far have identified strong association with classical class II alleles, in particular HLA-DRB1*0301 and HLA-DRB1*1501. Additional associations have been reported with class III alleles; specifically, complement C4 null alleles and a tumor necrosis factor promoter SNP (TNF-308G/A). However, the relative effects of these class II and class III variants have not been determined. We have thus used a family-based approach to map association signals across the MHC class II and class III regions in a cohort of 314 complete United Kingdom Caucasian SLE trios by typing tagging SNPs together with classical typing of the HLA-DRB1 locus. Using TDT and conditional regression analyses, we have demonstrated the presence of two distinct and independent association signals in SLE: HLA-DRB1*0301 (nominal p = 4.9 × 10−8, permuted p < 0.0001, OR = 2.3) and the T allele of SNP rs419788 (nominal p = 4.3 × 10−8, permuted p < 0.0001, OR = 2.0) in intron 6 of the class III region gene SKIV2L. Assessment of genotypic risk demonstrates a likely dominant model of inheritance for HLA-DRB1*0301, while rs419788-T confers susceptibility in an additive manner. Furthermore, by comparing transmitted and untransmitted parental chromosomes, we have delimited our class II signal to a 180 kb region encompassing the alleles HLA-DRB1*0301-HLA-DQA1*0501-HLA-DQB1*0201 alone. Our class III signal importantly excludes independent association at the TNF promoter polymorphism, TNF-308G/A, in our SLE cohort and provides a potentially novel locus for future genetic and functional studies.
Author Summary
Systemic lupus erythematosus (SLE/lupus) is a complex autoimmune disease in which the body's immune system attacks its own tissues, causing inflammation in a variety of different organs such as the skin, joints, and kidneys. The cause of lupus is not known, but genes play a significant role in the predisposition to disease. The major histocompatibility complex (MHC) on Chromosome 6 contains at least 100 different genes that affect the immune system, including the genes with the strongest effect on lupus susceptibility. Despite the importance of the MHC in SLE, the identity of the actual genes in the MHC region that cause SLE has remained elusive. In the present study, we used the latest set of genetic markers present at the MHC in lupus families to identify the actual genes that affect the disease. To our knowledge, we have shown for the first time that two separate groups of genes are involved in SLE. One group of genes alters how the immune system may inappropriately target its own tissues in the disease. How the second set of genes predisposes to SLE is the subject of ongoing study.
doi:10.1371/journal.pgen.0030192
PMCID: PMC2065882  PMID: 17997607
7.  Preferential Binding to Elk-1 by SLE-Associated IL10 Risk Allele Upregulates IL10 Expression 
PLoS Genetics  2013;9(10):e1003870.
Immunoregulatory cytokine interleukin-10 (IL-10) is elevated in sera from patients with systemic lupus erythematosus (SLE) correlating with disease activity. The established association of IL10 with SLE and other autoimmune diseases led us to fine map causal variant(s) and to explore underlying mechanisms. We assessed 19 tag SNPs, covering the IL10 gene cluster including IL19, IL20 and IL24, for association with SLE in 15,533 case and control subjects from four ancestries. The previously reported IL10 variant, rs3024505 located at 1 kb downstream of IL10, exhibited the strongest association signal and was confirmed for association with SLE in European American (EA) (P = 2.7×10−8, OR = 1.30), but not in non-EA ancestries. SNP imputation conducted in EA dataset identified three additional SLE-associated SNPs tagged by rs3024505 (rs3122605, rs3024493 and rs3024495 located at 9.2 kb upstream, intron 3 and 4 of IL10, respectively), and SLE-risk alleles of these SNPs were dose-dependently associated with elevated levels of IL10 mRNA in PBMCs and circulating IL-10 protein in SLE patients and controls. Using nuclear extracts of peripheral blood cells from SLE patients for electrophoretic mobility shift assays, we identified specific binding of transcription factor Elk-1 to oligodeoxynucleotides containing the risk (G) allele of rs3122605, suggesting rs3122605 as the most likely causal variant regulating IL10 expression. Elk-1 is known to be activated by phosphorylation and nuclear localization to induce transcription. Of interest, phosphorylated Elk-1 (p-Elk-1) detected only in nuclear extracts of SLE PBMCs appeared to increase with disease activity. Co-expression levels of p-Elk-1 and IL-10 were elevated in SLE T, B cells and monocytes, associated with increased disease activity in SLE B cells, and were best downregulated by ERK inhibitor. Taken together, our data suggest that preferential binding of activated Elk-1 to the IL10 rs3122605-G allele upregulates IL10 expression and confers increased risk for SLE in European Americans.
Author Summary
Systemic lupus erythematosus (SLE), a debilitating autoimmune disease characterized by the production of pathogenic autoantibodies, has a strong genetic basis. Variants of the IL10 gene, which encodes cytokine interleukin-10 (IL-10) with known function of promoting B cell hyperactivity and autoantibody production, are associated with SLE and other autoimmune diseases, and serum IL-10 levels are elevated in SLE patients correlating with increased disease activity. In this study, to discover SLE-predisposing causal variant(s), we assessed variants within the genomic region containing IL10 and its gene family member IL19, IL20 and IL24 for association with SLE in case and control subjects from diverse ancestries. We identified SLE-associated SNP rs3122605 located at 9.2 kb upstream of IL10 as the most likely causal variant in subjects of European ancestry. The SLE-risk allele of rs3122605 was dose-dependently associated with elevated IL10 expression at both mRNA and protein levels in peripheral blood samples from SLE patients and controls, which could be explained, at least in part, by its preferential binding to Elk-1, a transcription factor activated in B cells during active disease of SLE patients. Elk-1-mediated IL-10 overexpression could be downregulated by inhibiting activation of mitogen-activated protein kinases, suggesting a potential therapeutic target for SLE.
doi:10.1371/journal.pgen.1003870
PMCID: PMC3794920  PMID: 24130510
8.  Association of Genetic Variants in Complement Factor H and Factor H-Related Genes with Systemic Lupus Erythematosus Susceptibility 
PLoS Genetics  2011;7(5):e1002079.
Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Variants of genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) within the chromosome 1q32 locus linked to SLE, have been associated with multiple human diseases and may contribute to dysregulated complement activation predisposing to SLE. We assessed 60 SNPs covering the CFH-CFHRs region for association with SLE in 15,864 case-control subjects derived from four ethnic groups. Significant allelic associations with SLE were detected in European Americans (EA) and African Americans (AA), which could be attributed to an intronic CFH SNP (rs6677604, in intron 11, Pmeta = 6.6×10−8, OR = 1.18) and an intergenic SNP between CFHR1 and CFHR4 (rs16840639, Pmeta = 2.9×10−7, OR = 1.17) rather than to previously identified disease-associated CFH exonic SNPs, including I62V, Y402H, A474A, and D936E. In addition, allelic association of rs6677604 with SLE was subsequently confirmed in Asians (AS). Haplotype analysis revealed that the underlying causal variant, tagged by rs6677604 and rs16840639, was localized to a ∼146 kb block extending from intron 9 of CFH to downstream of CFHR1. Within this block, the deletion of CFHR3 and CFHR1 (CFHR3-1Δ), a likely causal variant measured using multiplex ligation-dependent probe amplification, was tagged by rs6677604 in EA and AS and rs16840639 in AA, respectively. Deduced from genotypic associations of tag SNPs in EA, AA, and AS, homozygous deletion of CFHR3-1Δ (Pmeta = 3.2×10−7, OR = 1.47) conferred a higher risk of SLE than heterozygous deletion (Pmeta = 3.5×10−4, OR = 1.14). These results suggested that the CFHR3-1Δ deletion within the SLE-associated block, but not the previously described exonic SNPs of CFH, might contribute to the development of SLE in EA, AA, and AS, providing new insights into the role of complement regulators in the pathogenesis of SLE.
Author Summary
Systemic lupus erythematosus (SLE) is a complex autoimmune disease, associated with increased complement activation. Previous studies have provided evidence for the presence of SLE susceptibility gene(s) in the chromosome 1q31-32 locus. Within 1q32, genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) may contribute to the development of SLE, because genetic variants of these genes impair complement regulation and predispose to various human diseases. In this study, we tested association of genetic variants in the region containing CFH and CFHRs with SLE. We identified genetic variants predisposing to SLE in European American, African American, and Asian populations, which might be attributed to the deletion of CFHR3 and CFHR1 genes but not previously identified disease-associated exonic variants of CFH. This study provides the first evidence for consistent association between CFH/CFHRs and SLE across multi-ancestral SLE datasets, providing new insights into the role of complement regulators in the pathogenesis of SLE.
doi:10.1371/journal.pgen.1002079
PMCID: PMC3102741  PMID: 21637784
9.  Differential Genetic Associations for Systemic Lupus Erythematosus Based on Anti–dsDNA Autoantibody Production 
PLoS Genetics  2011;7(3):e1001323.
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.
Author Summary
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that can involve virtually any organ system. SLE patients produce antibodies that bind to their own cells and proteins (autoantibodies) which can cause irreversible organ damage. One particular SLE–related autoantibody directed at double-stranded DNA (anti–dsDNA) is associated with kidney involvement and more severe disease. Previous genome-wide association studies (GWAS) in SLE have studied SLE itself, not particular SLE manifestations. Therefore, we conducted this GWAS of anti–dsDNA autoantibody production to identify genetic associations with this clinically important autoantibody. We found that many previously identified SLE–associated genes are more strongly associated with anti–dsDNA autoantibody production than SLE itself, and they may be more accurately described as autoantibody propensity genes. No strong genetic associations were observed for SLE patients who do not produce anti–dsDNA autoantibodies, suggesting that other factors may have more influence in developing this type of SLE. Further investigation of these autoantibody propensity genes may lead to greater insight into the causes of autoantibody production and organ damage in SLE.
doi:10.1371/journal.pgen.1001323
PMCID: PMC3048371  PMID: 21408207
10.  Time to Renal Disease and End-Stage Renal Disease in PROFILE: A Multiethnic Lupus Cohort 
PLoS Medicine  2006;3(10):e396.
Background
Renal involvement is a serious manifestation of systemic lupus erythematosus (SLE); it may portend a poor prognosis as it may lead to end-stage renal disease (ESRD). The purpose of this study was to determine the factors predicting the development of renal involvement and its progression to ESRD in a multi-ethnic SLE cohort (PROFILE).
Methods and Findings
PROFILE includes SLE patients from five different United States institutions. We examined at baseline the socioeconomic–demographic, clinical, and genetic variables associated with the development of renal involvement and its progression to ESRD by univariable and multivariable Cox proportional hazards regression analyses. Analyses of onset of renal involvement included only patients with renal involvement after SLE diagnosis (n = 229). Analyses of ESRD included all patients, regardless of whether renal involvement occurred before, at, or after SLE diagnosis (34 of 438 patients). In addition, we performed a multivariable logistic regression analysis of the variables associated with the development of renal involvement at any time during the course of SLE.
In the time-dependent multivariable analysis, patients developing renal involvement were more likely to have more American College of Rheumatology criteria for SLE, and to be younger, hypertensive, and of African-American or Hispanic (from Texas) ethnicity. Alternative regression models were consistent with these results. In addition to greater accrued disease damage (renal damage excluded), younger age, and Hispanic ethnicity (from Texas), homozygosity for the valine allele of FcγRIIIa (FCGR3A*GG) was a significant predictor of ESRD. Results from the multivariable logistic regression model that included all cases of renal involvement were consistent with those from the Cox model.
Conclusions
Fcγ receptor genotype is a risk factor for progression of renal disease to ESRD. Since the frequency distribution of FCGR3A alleles does not vary significantly among the ethnic groups studied, the additional factors underlying the ethnic disparities in renal disease progression remain to be elucidated.
Fcγ receptor genotype is a risk factor for progression of renal disease to ESRD but does not explain the ethnic disparities in renal disease progression.
Editors' Summary
Background.
Systemic lupus erythematosis (SLE, commonly known as “lupus”) is an illness of many manifestations that appear to result from the immune system attacking components of the body's own cells. One of the unfortunate effects of SLE is kidney damage, which can, in a minority of patients, progress to kidney failure (formally called “end-stage renal disease,” or ESRD). Compared to White Americans, other ethnic groups tend to develop renal complications of lupus more often and with worse outcomes.
Why Was This Study Done?
It is unclear why some people with lupus develop kidney problems. The purpose of this US-based study was to confirm the factors that increase the risk of kidney damage and kidney failure, particularly in racial and ethnic minority patients, and to determine which of these factors accelerate the pace of kidney disease. Knowing these risk factors could allow the development and targeting of interventions, such as screening tests and preventive treatments, to prevent long-term loss of kidney function in patients with lupus.
What Did the Researchers Do and Find?
The researchers measured a number of factors in a multi-ethnic group of 1,008 patients with lupus, almost half of whom had some degree of kidney involvement. They found that those who developed kidney damage after being diagnosed with lupus tended to be younger, to have had lupus for a longer time, and to have experienced more effects of lupus in general than those who did not have kidney involvement. Those who developed kidney problems were also more likely to have been unemployed, to have had fewer years of formal education, and to have had high blood pressure before developing kidney involvement. African-American and Texan Hispanic individuals with lupus were more likely to develop kidney involvement, and tended to develop it more rapidly, than White Americans or Puerto Rican Hispanic ethnicity. Actual kidney failure (ESRD requiring dialysis or kidney transplantation) was more likely to occur among Texan Hispanics with kidney involvement than in the other ethnic groups. Diabetes and high blood pressure were not found to predict ESRD, but people with a particular variant of a protein that helps antibodies bind to cells (know as Fc-gamma receptor IIIa, or FcγRIIIa) were found to be more likely to develop ESRD, and to develop it more quickly.
What Do These Findings Mean?
These results suggest that the emergence and progression of kidney disease in patients with lupus depends on medical, genetic, and socioeconomic factors. Because no single test or intervention can be expected to address all of these factors, those treating patients with lupus must remain aware of the complexity of their patients lives at a variety of levels. In particular, ethnic disparities in the risk of serious kidney disease remain to be addressed.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030396.
MedlinePlus page on lupus
Lupus Foundation of America
American College of Rheumatology pages on lupus
Wikipedia entry on lupus (note: Wikipedia is a free Internet encyclopedia that anyone can edit)
doi:10.1371/journal.pmed.0030396
PMCID: PMC1626549  PMID: 17076550
11.  MicroRNA-3148 Modulates Allelic Expression of Toll-Like Receptor 7 Variant Associated with Systemic Lupus Erythematosus 
PLoS Genetics  2013;9(2):e1003336.
We previously reported that the G allele of rs3853839 at 3′untranslated region (UTR) of Toll-like receptor 7 (TLR7) was associated with elevated transcript expression and increased risk for systemic lupus erythematosus (SLE) in 9,274 Eastern Asians [P = 6.5×10−10, odds ratio (OR) (95%CI) = 1.27 (1.17–1.36)]. Here, we conducted trans-ancestral fine-mapping in 13,339 subjects including European Americans, African Americans, and Amerindian/Hispanics and confirmed rs3853839 as the only variant within the TLR7-TLR8 region exhibiting consistent and independent association with SLE (Pmeta = 7.5×10−11, OR = 1.24 [1.18–1.34]). The risk G allele was associated with significantly increased levels of TLR7 mRNA and protein in peripheral blood mononuclear cells (PBMCs) and elevated luciferase activity of reporter gene in transfected cells. TLR7 3′UTR sequence bearing the non-risk C allele of rs3853839 matches a predicted binding site of microRNA-3148 (miR-3148), suggesting that this microRNA may regulate TLR7 expression. Indeed, miR-3148 levels were inversely correlated with TLR7 transcript levels in PBMCs from SLE patients and controls (R2 = 0.255, P = 0.001). Overexpression of miR-3148 in HEK-293 cells led to significant dose-dependent decrease in luciferase activity for construct driven by TLR7 3′UTR segment bearing the C allele (P = 0.0003). Compared with the G-allele construct, the C-allele construct showed greater than two-fold reduction of luciferase activity in the presence of miR-3148. Reduced modulation by miR-3148 conferred slower degradation of the risk G-allele containing TLR7 transcripts, resulting in elevated levels of gene products. These data establish rs3853839 of TLR7 as a shared risk variant of SLE in 22,613 subjects of Asian, EA, AA, and Amerindian/Hispanic ancestries (Pmeta = 2.0×10−19, OR = 1.25 [1.20–1.32]), which confers allelic effect on transcript turnover via differential binding to the epigenetic factor miR-3148.
Author Summary
Systemic lupus erythematosus (SLE) is a debilitating autoimmune disease contributed to by excessive innate immune activation involving toll-like receptors (TLRs, particularly TLR7/8/9) and type I interferon (IFN) signaling pathways. TLR7 responds against RNA–containing nuclear antigens and activates IFN-α pathway, playing a pivotal role in the development of SLE. While a genomic duplication of Tlr7 promotes lupus-like disease in the Y-linked autoimmune accelerator (Yaa) murine model, the lack of common copy number variations at TLR7 in humans led us to identify a functional single nucleotide polymorphism (SNP), rs3853839 at 3′ UTR of the TLR7 gene, associated with SLE susceptibility in Eastern Asians. In this study, we fine-mapped the TLR7-TLR8 region and confirmed rs3853839 exhibiting the strongest association with SLE in European Americans, African Americans, and Amerindian/Hispanics. Individuals carrying the risk G allele of rs3853839 exhibited increased TLR7 expression at the both mRNA and protein level and decreased transcript degradation. MicroRNA-3148 (miR-3148) downregulated the expression of non-risk allele (C) containing transcripts preferentially, suggesting a likely mechanism for increased TLR7 levels in risk-allele carriers. This trans-ancestral mapping provides evidence for the global association with SLE risk at rs3853839, which resides in a microRNA–gene regulatory site affecting TLR7 expression.
doi:10.1371/journal.pgen.1003336
PMCID: PMC3585142  PMID: 23468661
12.  The role of X-chromosome inactivation in female predisposition to autoimmunity 
Arthritis Research  2000;2(5):399-406.
We propose that the phenomenon of X-chromosome inactivation in females may constitute a risk factor for loss of T-cell tolerance; specifically that skewed X-chromosome inactivation in the thymus may lead to inadequate thymic deletion. Using a DNA methylation assay, we have examined the X-chromosome inactivation patterns in peripheral blood from normal females (n = 30), female patients with a variety of autoimmune diseases (n = 167). No differences between patients and controls were observed. However, locally skewed X-chromsome inactivation may exist in the thymus, and therefore the underlying hypothesis remains to be disproved.
Introduction:
A reduction in the sex ratio (male : female) is characteristic of most autoimmune disorders. The increased prevalence in females ranges from a modest 2:1 for multiple sclerosis [1], to approximately 10:1 for systemic lupus erythematosus [2]. This tendency toward autoimmunity in females is often ascribed to hormonal differences, because in a number of experimental disease models estrogens exacerbated disease, and androgens can inhibit disease activity [3,4]. However, human studies have failed to demonstrate a clear-cut influence of hormonal environment on disease susceptibility to lupus or other autoimmune disorders. In addition, many childhood forms of autoimmunity, such as juvenile rheumatoid arthritis, exhibit female predominance [5]. Interestingly, juvenile (type 1) diabetes is an exception to this general trend, with a sex ratio close to 1 in most studies [6]. Therefore, it is reasonable to consider alternative explanations for the increased prevalence of autoimmune diseases in human females.
A unifying feature of autoimmune disorders appears to be the loss of immunologic tolerance to self-antigens, and in many of these diseases there is evidence that T-cell tolerance has been broken. The most profound form of T-cell tolerance involves deletion of potentially self-reactive T cells during thymic selection. Thus, lack of exposure to a self-antigen in the thymus may lead to the presence of autoreactive T cells and may increase the risk of autoimmunity. An elegant example of this has recently been reported [7].
The existence of X-chromosome inactivation in females offers a potential mechanism whereby X-linked self-antigens may escape presentation in the thymus or in other peripheral sites that are involved in tolerance induction. Early in female development, one of the two X chromosomes in each cell undergoes an ordered process of inactivation, with subsequent silencing of most genes on the inactive X chromosome [8]. This phenomenon occurs at a very early embryonic stage [9], and thus all females are mosaic and may occasionally exhibit extreme skewing towards one or the other parental X chromosome. In theory, this may result in a situation in which polymorphic self-antigens on one X chromosome may fail to be expressed at sufficiently high levels in a tolerizing compartment, such as the thymus, and yet may be expressed at a considerable frequency in the peripheral soma. Thus, females may be predisposed to a situation in which they can occasionally express X-linked autoantigens in the periphery to which they have been inefficiently tolerized. Stewart [10] has recently speculated that such a mechanism may play a role in the predisposition to systemic lupus.
This hypothesis predicts that females with autoimmunity may be particularly prone to this mechanism of `inadequate tolerization' by virtue of extremely skewed X-chromosome inactivation. We therefore performed a comprehensive analysis of X-chromosome inactivation patterns in populations of females with multiple sclerosis, systemic lupus erythematosus, juvenile rheumatoid arthritis, and type 1 (insulin-dependent) diabetes mellitus, and in female control individuals. The results do not provide support for a major role for skewed X-chromosome inactivation in female predisposition to autoimmunity; however, neither is the underlying hypothesis disproved by the present data.
Materials and method:
DNA was obtained from female patients from the following sources: 45 persons with juvenile diabetes seen at the Virginia Mason Research Center in Seattle, Washington; 58 multiple sclerosis patients seen at the New York Hospital Multiple Sclerosis Center; 46 patients with systemic lupus erythematosus seen at the Hospital for Special Surgery (New York); 18 patients with juvenile rheumatoid arthritis seen at the Children's Hospital Medical Center in Cleveland. In addition, 30 healthy age-matched females were studied as normal controls.
Employing a modification of previously described methods [11], we utilized a fluorescent Hpa II/PCR assay of the androgen receptor (AR) locus to assess X-chromosome inactivation patterns. The AR gene contains a polymorphic CAG repeat, which is flanked by Hpa II sites. These Hpa II sites are methylated on the inactive X chromosome, and are unmethylated on the active X chromosome. By performing PCR amplification across this region after cutting with the methylation-sensitive enzyme Hpa II, the relative amounts of the methylated AR alleles can be quantitatively determined with a high degree of accuracy; variance on repeated assays is approximately 4% [12].
Skewing of X-chromosome inactivation is expressed as percentage deviation from equal (50:50) inactivation of the upper and lower AR alleles. Therefore, the maximal possible deviation is 50%, in which case all of the X chromosomes bearing one of the AR alleles are inactivated.
Results:
We examined X-chromosome inactivation patterns in several different populations. The results are summarized in Fig. 1. A wide range of X-inactivation skewing was observed in all five groups. Approximately 5% (nine out of 197) of individuals exhibited extreme skewing (greater than 40% deviation from a 50:50 distribution). However, there was no difference between the groups, either in the overall mean skewing, or in the fraction of individuals with extreme skewing (>40%).
Although the present study was not initiated in order to examine allelic variation in the AR gene per se, the data provide an opportunity to address this question. Excessively long CAG repeats in the AR are a rare cause of spinal-bulbar muscular atrophy [13], and AR repeat length appears to have an influence on the biology of certain tumors [14,15]. In this context, it has been shown that transcription of AR correlates inversely with repeat length [16]. We therefore compared AR repeat length in control individuals and patients with autoimmunity. No differences were observed for mean repeat length, or for maximum and minimum repeat length, among the five groups.
Discussion:
The reason for the female predominance in most autoimmune diseases remains obscure. The present study was initiated in order to address the hypothesis that a nonhormonal mechanism related to X inactivation might be involved. The hypothesis rests on the idea that skewing of X inactivation might lead to a deficiency of tolerance induction in the thymus, particularly with respect to polymorphic X-linked autoantigens. The hypothesis predicts that skewed X inactivation would be more prevalent in females with autoimmune diseases than in female control individuals. This was not observed.
Nevertheless, these negative data do not rule out a role for X inactivation in female predisposition to loss of tolerance. A general model for how this mechanism might operate is shown in Fig. 2. Thymocytes undergo selection in the thymic parenchyma and, in the case of negative selection, the selecting elements appear to be derived from the bone marrow and consist mainly of thymic dendritic cells. If the thymic dendritic cell population exhibits random X inactivation, it is highly likely that differentiating thymocytes will contact dendritic cells that express self-antigens on both X chromosomes. This situation is outlined schematically on the left side of Fig. 2. However, if there is extremely skewed X inactivation in the thymic dendritic cell population, a particular thymocyte might not come into contact with dendritic cells that express one of the two X chormosomes. This would lead to a situation where T cells may undergo thymic maturation without having been negatively selected for antigens that are expressed on the predominantly inactive X chromosome. This situation is shown on the right side of Fig. 2.
In order for this mechanism to be physiologically relevant, some assumptions must be made. First, defective tolerance from skewed X inactivation should only be directed at X-linked antigens that are polymorphic, and for which the individual is heterozygous. Thus, this mechanism would not be expected to lead to lack of tolerance commonly, unless there are at least several highly polymorphic X-linked autoantigens in the population that are involved in thymic deletion events. Second, if this actually leads to autoimmunity, it also predicts that the initial break in tolerance that leads to disease should involve an X-linked autoantigen that is expressed in a peripheral nontolerizing site or circumstance.
A recent report [7] has elegantly demonstrated the importance of thymic deletion events in predisposition to autoimmune disease. The proteolipid protein (PLP) autoantigen is expressed in alternatively spliced forms, which exhibit tissue specific expression. A nonspliced variant is expressed in peripheral neural tissue. However, in the thymus a splice variant results in the lack of thymic expression of an immunodominant peptide. This results in loss of tolerace of T cells to this peptide, presumably on the basis of lack of thymic deletion of thymocytes that are reactive with this antigen. Interestingly, PLP is encoded on the X chromsome. However, there is no evidence that genetic polymorphisms control the level splicing of PLP within the thymus. Nevertheless, these data illustrate the potential importance of deficiencies in thymic deletion for autoimmune T-cell reactivity.
The present results suggest that if skewed X inactivation is relevant to thymic tolerance induction, then the effect does not depend on global skewing of X-chromosome inactivation, at least in the hematopoietic compartment. In this study we examined X-inactivation patterns in peripheral blood mononuclear cells, and the results should reflect the state of X inactivation in all mesenchymal tissues, including dendritic cells. X inactivation occurs at a very early time point in development, and thus the results in one tissue should reflect the general situation in the rest of the body. However, there may be exceptions to this. We have occasionally observed differences in X-inactivation patterns between buccal mucosa (an ectodermally derived tissue) and peripheral blood in the same individiual (unpublished observations). This could be a chance event, or it may result from selection for certain X-linked alleles during embryonic development, as has been described in carriers of X-linked immunodeficiencies [17].
Another consideration is that certain tissue microenvironments may be derived from very small numbers of founder cells, and thus may exhibit skewed utilization of one or the other X chromosome, even if the tissue as a whole is not skewed. This situation could vary over time. Thus, there may be time points at which certain thymic microenvironments are populated by dendritic cells that, for stochastic reasons, all utilize the same X chromosome. This would create a `window of opportunity' in which a given thymocyte, in a given selecting location, could escape negative selection by antigens on the inactive X chromosome. The likelihood of this happening would obviously depend on the number of dendritic cells that are usually contacted by a thymocyte during thymic selection. There is limited information on this point, although Stewart [10] has theorized that this number may be as low as 15. If this is the case, then escape from thymic deletion may still occur in females who are heterozygous for a relevant X-linked antigen, even if the hematopoietic cells in general do not exhibit extreme skewing.
In conclusion, we suggest that X-chromosome inactivation needs to be considered as a potential factor in the predominance of females in most autoimmune diseases. Our inability to show an increase in X-chromosome skewing in females with autoimmunity does not eliminate this as an etiologic contributor to loss of immunologic tolerance. Future experiments must be directed at a detailed analysis of tissue patterns of X inactivation, as well as at a search for potential X-linked autoantigens.
PMCID: PMC17816  PMID: 11056674
autoimmunity; gender; immune tolerance; X chromosome
13.  The A-G polymorphism in exon 1 of the CTLA-4 gene is not associated with systemic lupus erythematosus 
Annals of the Rheumatic Diseases  1999;58(3):193-195.
OBJECTIVES—Factors contributing to the development of systemic lupus erythematosus (SLE) remain largely unknown although are likely to include both environmental and genetic components. Studies on murine lupus have indicated a role for an antibody that blocks binding of cytotoxic T lymphocyte associated-4 (CTLA-4) to B7 on antigen presenting cells in the treatment of disease, suggesting that CTLA-4 may play an important part in the disease process. This study, therefore, investigated the frequency of a previously described A-G polymorphism in exon 1 of the CTLA-4 gene, the G allele of which has shown to be associated with both Graves' disease and type I diabetes, to determine whether this polymorphism was playing a part in the development of SLE.
METHODS—One hundred and twenty six SLE patients and 363 control subjects were genotyped for the A-G polymorphism in exon 1 of the CTLA-4 gene. Target DNA was amplified using the polymerase chain reaction and the resulting product was digested using the BbvI restriction enzyme.
RESULTS—No differences in allele or genotype frequencies were observed between patients with SLE and control subjects.
CONCLUSION—These data suggest that the A-G polymorphism in exon 1 of the CTLA-4 gene does not play a part in the genetic susceptibility to the development of SLE.

 Keywords: CTLA-4; systemic lupus erythematosus
PMCID: PMC1752847  PMID: 10364920
14.  High-Density SNP Screening of the Major Histocompatibility Complex in Systemic Lupus Erythematosus Demonstrates Strong Evidence for Independent Susceptibility Regions 
PLoS Genetics  2009;5(10):e1000696.
A substantial genetic contribution to systemic lupus erythematosus (SLE) risk is conferred by major histocompatibility complex (MHC) gene(s) on chromosome 6p21. Previous studies in SLE have lacked statistical power and genetic resolution to fully define MHC influences. We characterized 1,610 Caucasian SLE cases and 1,470 parents for 1,974 MHC SNPs, the highly polymorphic HLA-DRB1 locus, and a panel of ancestry informative markers. Single-marker analyses revealed strong signals for SNPs within several MHC regions, as well as with HLA-DRB1 (global p = 9.99×10−16). The most strongly associated DRB1 alleles were: *0301 (odds ratio, OR = 2.21, p = 2.53×10−12), *1401 (OR = 0.50, p = 0.0002), and *1501 (OR = 1.39, p = 0.0032). The MHC region SNP demonstrating the strongest evidence of association with SLE was rs3117103, with OR = 2.44 and p = 2.80×10−13. Conditional haplotype and stepwise logistic regression analyses identified strong evidence for association between SLE and the extended class I, class I, class III, class II, and the extended class II MHC regions. Sequential removal of SLE–associated DRB1 haplotypes revealed independent effects due to variation within OR2H2 (extended class I, rs362521, p = 0.006), CREBL1 (class III, rs8283, p = 0.01), and DQB2 (class II, rs7769979, p = 0.003, and rs10947345, p = 0.0004). Further, conditional haplotype analyses demonstrated that variation within MICB (class I, rs3828903, p = 0.006) also contributes to SLE risk independent of HLA-DRB1*0301. Our results for the first time delineate with high resolution several MHC regions with independent contributions to SLE risk. We provide a list of candidate variants based on biologic and functional considerations that may be causally related to SLE risk and warrant further investigation.
Author Summary
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and involvement of multiple organ systems. Although the cause of SLE remains unknown, several lines of evidence underscore the importance of genetic factors. As is true for most autoimmune diseases, a substantial genetic contribution to disease risk is conferred by major histocompatibility complex (MHC) gene(s) on chromosome 6. This region of the genome contains a large number of genes that participate in the immune response. However, the full contribution of this genomic region to SLE risk has not yet been defined. In the current study we characterize a large number of SLE patients and family members for approximately 2,000 MHC region variants to identify the specific genes that influence disease risk. Our results, for the first time, implicate four different MHC regions in SLE risk. We provide a list of candidate variants based on biologic and functional considerations that may be causally related to SLE risk and warrant further investigation.
doi:10.1371/journal.pgen.1000696
PMCID: PMC2758598  PMID: 19851445
15.  Trans-Ancestral Studies Fine Map the SLE-Susceptibility Locus TNFSF4 
PLoS Genetics  2013;9(7):e1003554.
We previously established an 80 kb haplotype upstream of TNFSF4 as a susceptibility locus in the autoimmune disease SLE. SLE-associated alleles at this locus are associated with inflammatory disorders, including atherosclerosis and ischaemic stroke. In Europeans, the TNFSF4 causal variants have remained elusive due to strong linkage disequilibrium exhibited by alleles spanning the region. Using a trans-ancestral approach to fine-map the locus, utilising 17,900 SLE and control subjects including Amerindian/Hispanics (1348 cases, 717 controls), African-Americans (AA) (1529, 2048) and better powered cohorts of Europeans and East Asians, we find strong association of risk alleles in all ethnicities; the AA association replicates in African-American Gullah (152,122). The best evidence of association comes from two adjacent markers: rs2205960-T (P = 1.71×10−34, OR = 1.43[1.26–1.60]) and rs1234317-T (P = 1.16×10−28, OR = 1.38[1.24–1.54]). Inference of fine-scale recombination rates for all populations tested finds the 80 kb risk and non-risk haplotypes in all except African-Americans. In this population the decay of recombination equates to an 11 kb risk haplotype, anchored in the 5′ region proximal to TNFSF4 and tagged by rs2205960-T after 1000 Genomes phase 1 (v3) imputation. Conditional regression analyses delineate the 5′ risk signal to rs2205960-T and the independent non-risk signal to rs1234314-C. Our case-only and SLE-control cohorts demonstrate robust association of rs2205960-T with autoantibody production. The rs2205960-T is predicted to form part of a decameric motif which binds NF-κBp65 with increased affinity compared to rs2205960-G. ChIP-seq data also indicate NF-κB interaction with the DNA sequence at this position in LCL cells. Our research suggests association of rs2205960-T with SLE across multiple groups and an independent non-risk signal at rs1234314-C. rs2205960-T is associated with autoantibody production and lymphopenia. Our data confirm a global signal at TNFSF4 and a role for the expressed product at multiple stages of lymphocyte dysregulation during SLE pathogenesis. We confirm the validity of trans-ancestral mapping in a complex trait.
Author Summary
Systemic lupus erythematosus (SLE/lupus) is a complex disease in which the body's immune cells cause inflammation in one or more systems to cause the associated morbidity. Hormones, the environment and genes are all causal contributors to SLE and over the past several years the genetic component of SLE has been firmly established. Several genes which are regulators of the immune system are associated with disease risk. We have established one of these, the tumour-necrosis family superfamily member 4 (TNFSF4) gene, as a lupus susceptibility gene in Northern Europeans. A major obstacle in pinpointing the marker(s) at TNFSF4 which best explain the risk of SLE has been the strong correlation (linkage disequilibrium, LD) between adjacent markers across the TNFSF4 region in this population. To address this, we have typed polymorphisms in several populations in addition to the European groups. The mixed ancestry of these populations gives a different LD pattern than that found in Europeans, presenting a method of pinpointing the section of the TNFSF4 region which results in SLE susceptibility. The Non-European populations have allowed identification of a polymorphism likely to regulate expression of TNFSF4 to increase susceptibility to SLE.
doi:10.1371/journal.pgen.1003554
PMCID: PMC3715547  PMID: 23874208
16.  Association between a T cell receptor restriction fragment length polymorphism and systemic lupus erythematosus. 
Journal of Clinical Investigation  1990;86(6):1961-1967.
The present study was designed to test the possibility that T cell receptor genes are associated/linked to those involved in systemic lupus erythematosus (SLE). Genomic DNA was isolated from 31 unrelated Caucasian SLE patients, 34 unrelated Caucasian normals, 5 multiplex American Caucasian SLE families, 9 multiplex Mexican SLE families, and 13 unrelated Mexican normals. The DNA was digested with Pst I, electrophoresed, and transferred to membranes by the Southern blot method. The blots were probed with a cDNA probe for the alpha chain of the T cell receptor. 13 polymorphic RFLP patterns were recognized. 1.3- and 3.0-kb band pairs were observed in 15 of 31 of American Caucasian patients and 4 of 34 American Caucasian controls (chi square, 8.81; P less than 0.002; relative risk, 7); there was no association of any RFLP pattern with Mexican SLE. The cDNA probe was cut with Rsa I, EcoR I, and Ava II into fragments corresponding to the V, J, C, and 3'UT regions. Only the fragment corresponding to the constant region reacted with the 1.3/3.0-kb band pair. These observations suggest that a genetic marker of the constant region of the alpha chain of the T cell receptor is associated with genes involved in SLE.
Images
PMCID: PMC329832  PMID: 1979334
17.  Combination Effect of GSTM1, GSTT1 and GSTP1 Polymorphisms and Risk of Systemic Lupus Erythematosus 
Iranian Journal of Public Health  2015;44(6):814-821.
Background:
Progression of systemic lupus erythematosus (SLE) could be due to oxidative stress especially through reactive oxygen species (ROS). Detoxification of ROS is largely performed by Glutathione S-transferases (GSTs), therefore polymorphisms of GSTM1, GSTT1 and GSTP1 genes which decrease enzymes activity could affect SLE susceptibility. The aim of this study was to determine the effects of GSTM1 (deletion), GSTT1 (deletion) and GSTP1 (Ile105Val) polymorphisms on SLE susceptibility.
Methods:
Genomic DNA was extracted from blood samples of 163 SLE patients and 180 age, sex and ethnically matched controls. GSTs genotypes were determined by polymerase chain reaction (PCR)-multiplex procedure or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.
Results:
GSTT1 null genotype frequency was higher in SLE patients than controls. NO association observed between GSTM1 null genotype or GSTP1 Ile105Val polymorphism with SLE. Nevertheless combination of GSTT1 null/ GSTM1 null genotypes showed 2.8-fold increase in risk of SLE. Moreover the combination of GSTT1 null/ GSTM1 null/GSTP1 Ile/Val and Val/Val genotypes increased the SLE risk about 8 fold.
Conclusion:
Present data suggest that GSTT1 null/ GSTM1 null/GSTP1 Ile/Val and Val/Val genotypes might largely contribute to the pathogenesis of SLE.
PMCID: PMC4524306  PMID: 26258094
Systemic lupus erythematosus; Glutathione S-transferase; Gene; Polymorphism
18.  Risk Alleles for Systemic Lupus Erythematosus in a Large Case-Control Collection and Associations with Clinical Subphenotypes 
PLoS Genetics  2011;7(2):e1001311.
Systemic lupus erythematosus (SLE) is a genetically complex disease with heterogeneous clinical manifestations. Recent studies have greatly expanded the number of established SLE risk alleles, but the distribution of multiple risk alleles in cases versus controls and their relationship to subphenotypes have not been studied. We studied 22 SLE susceptibility polymorphisms with previous genome-wide evidence of association (p<5×10−8) in 1919 SLE cases from 9 independent Caucasian SLE case series and 4813 independent controls. The mean number of risk alleles in cases was 15.1 (SD 3.1) while the mean in controls was 13.1 (SD 2.8), with trend p = 4×10−128. We defined a genetic risk score (GRS) for SLE as the number of risk alleles with each weighted by the SLE risk odds ratio (OR). The OR for high-low GRS tertiles, adjusted for intra-European ancestry, sex, and parent study, was 4.4 (95% CI 3.8–5.1). We studied associations of individual SNPs and the GRS with clinical manifestations for the cases: age at diagnosis, the 11 American College of Rheumatology classification criteria, and double-stranded DNA antibody (anti-dsDNA) production. Six subphenotypes were significantly associated with the GRS, most notably anti-dsDNA (ORhigh-low = 2.36, p = 9e−9), the immunologic criterion (ORhigh-low = 2.23, p = 3e−7), and age at diagnosis (ORhigh-low = 1.45, p = 0.0060). Finally, we developed a subphenotype-specific GRS (sub-GRS) for each phenotype with more power to detect cumulative genetic associations. The sub-GRS was more strongly associated than any single SNP effect for 5 subphenotypes (the above plus hematologic disorder and oral ulcers), while single loci are more significantly associated with renal disease (HLA-DRB1, OR = 1.37, 95% CI 1.14–1.64) and arthritis (ITGAM, OR = 0.72, 95% CI 0.59–0.88). We did not observe significant associations for other subphenotypes, for individual loci or the sub-GRS. Thus our analysis categorizes SLE subphenotypes into three groups: those having cumulative, single, and no known genetic association with respect to the currently established SLE risk loci.
Author Summary
Systemic lupus erythematosus is a chronic disabling autoimmune disease, most commonly striking women in their thirties or forties. It can cause a wide variety of clinical manifestations, including kidney disease, arthritis, and skin disorders. Prognosis varies greatly depending on these clinical features, with kidney disease and related characteristics leading to greater morbidity and mortality. It is also complex genetically; while lupus runs in families, genes increase one's risk for lupus but do not fully determine the outcome. The interactions of multiple genes and/or interactions between genes and environmental factors may cause lupus, but the causes and disease pathways of this very heterogeneous disease are not well understood. By examining relationships between the presence of multiple lupus risk genes, lupus susceptibility, and clinical manifestations, we hope to better understand how lupus is triggered and by what biological pathways it progresses. We show in this work that certain clinical manifestations of lupus are highly associated with cumulative genetic variations, i.e. multiple risk alleles, while others are associated with a single variation or none at all.
doi:10.1371/journal.pgen.1001311
PMCID: PMC3040652  PMID: 21379322
19.  A Dinucleotide Deletion in CD24 Confers Protection against Autoimmune Diseases 
PLoS Genetics  2007;3(4):e49.
It is generally believed that susceptibility to both organ-specific and systemic autoimmune diseases is under polygenic control. Although multiple genes have been implicated in each type of autoimmune disease, few are known to have a significant impact on both. Here, we investigated the significance of polymorphisms in the human gene CD24 and the susceptibility to multiple sclerosis (MS) and systemic lupus erythematosus (SLE). We used cases/control studies to determine the association between CD24 polymorphism and the risk of MS and SLE. In addition, we also considered transmission disequilibrium tests using family data from two cohorts consisting of a total of 150 pedigrees of MS families and 187 pedigrees of SLE families. Our analyses revealed that a dinucleotide deletion at position 1527∼1528 (P1527del) from the CD24 mRNA translation start site is associated with a significantly reduced risk (odds ratio = 0.54 with 95% confidence interval = 0.34–0.82) and delayed progression (p = 0.0188) of MS. Among the SLE cohort, we found a similar reduction of risk with the same polymorphism (odds ratio = 0.38, confidence interval = 0.22–0.62). More importantly, using 150 pedigrees of MS families from two independent cohorts and the TRANSMIT software, we found that the P1527del allele was preferentially transmitted to unaffected individuals (p = 0.002). Likewise, an analysis of 187 SLE families revealed the dinucleotide-deleted allele was preferentially transmitted to unaffected individuals (p = 0.002). The mRNA levels for the dinucleotide-deletion allele were 2.5-fold less than that of the wild-type allele. The dinucleotide deletion significantly reduced the stability of CD24 mRNA. Our results demonstrate that a destabilizing dinucleotide deletion in the 3′ UTR of CD24 mRNA conveys significant protection against both MS and SLE.
Author Summary
When an individual's immune system attacks self tissues or organs, he/she develops autoimmune diseases. Although it is well established that multiple genes control susceptibility to autoimmune diseases, most of the genes remain unidentified. In addition, although different autoimmune diseases have a common immunological basis, a very small number of genes have been identified that affect multiple autoimmune diseases. Here we show that a variation in CD24 is a likely genetic factor for the risk and progression of two types of autoimmune diseases, including multiple sclerosis (MS), an organ-specific autoimmune disease affecting the central nervous system, and systemic lupus erythematosus, a systemic autoimmune disease. Our data indicated that if an individual's CD24 gene has a specific two-nucleotide deletion in the noncoding region of CD24 mRNA, his/her risk of developing MS or SLE is reduced by 2- to 3-fold. As a group, MS patients with the two-nucleotide deletion will likely have a slower disease progression. Biochemical analysis indicated that the deletion leads to rapid decay of CD24 mRNA, which should result in reduced synthesis of the CD24 protein. Our data may be useful for the treatment and diagnosis of autoimmune diseases.
doi:10.1371/journal.pgen.0030049
PMCID: PMC1847692  PMID: 17411341
20.  Vitamin D receptor gene BsmI polymorphisms in Egyptian children and adolescents with systemic lupus erythematosus 
Medicine  2016;95(46):e5233.
Abstract
Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease. The vitamin D receptor (VDR) gene is a candidate gene for susceptibility to autoimmune disorders. To date, only a few studies concerned the association of the VDR gene polymorphisms with childhood-onset SLE.
In this study, we aimed to investigate the BsmI polymorphisms in the VDR gene, for the first time in Egyptian children and adolescents with SLE, to determine whether this polymorphism could be a marker of susceptibility to or severity of SLE and we also measured the serum level of 25-hydroxyvitamin D (25[OH] D) to assess its relation to such polymorphism.
This was a case–control study including 100 patients with SLE and matched with age, sex, and ethnicity and 100 healthy controls. All subjects were genotyped for the VDR gene BsmI polymorphism by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), whereas the serum 25(OH) D levels were measured by enzyme-linked immunosorbent assay method.
Compared to the contros subjects, the VDR BsmI BB genotype and B allele were overrepresented among SLE patients (odda ratio [OR]: 5.5; 95% confidence interval [CI]: 1.9–15.9; P = 0.002 and OR: 1.84; 95% CI: 1.21–2.80; P = 0.003; respectively). We found a significant association between VDR BsmI BB genotype with lupus nephritis (OR: 6.8; 95% CI: 1.18–50.5; P = 0.001). However, we did not observe any significant association of studied polymorphisms with other clinical manifestations, laboratory profiles of SLE, or disease activity score. Our data revealed no association between VDR BsmI genotypes or alleles and serum 25-hydroxyvitamin D levels among studied patients with SLE (all P > 0.05).
We demonstrate for the first time, to the best of our knowledge, that the VDR BsmI gene polymorphisms may contribute to susceptibility to SLE in Egyptian children and adolescents. Moreover, we found that the BB genotype constituted a risk factor for the development of nephropathy among studied patients with SLE. However, we did not find any significant association of the VDR BsmI gene variants with other clinical manifestations, laboratory profiles of SLE, disease activity index score, or serum 25-hydroxyvitamin D levels.
doi:10.1097/MD.0000000000005233
PMCID: PMC5120902  PMID: 27861345
adolescents; children; gene polymorphisms; systemic lupus erythematosus; vitamin D receptors
21.  A highly informative probe for two polymorphic Vh gene regions that contain one or more autoantibody-associated Vh genes. 
Journal of Clinical Investigation  1989;84(2):706-710.
Efforts to determine the role of specific Ig variable region (V) genes in human autoimmune responses have been hampered by the lack of suitably polymorphic probes. Recently we isolated a heavy chain V (Vh) gene, designated Humhv3005, that is 99% homologous to the 1.9III Vh gene and can encode an anti-DNA antibody. To study the relation between these two genes, different DNA fragments from the isolated Humhv3005 clone were used to probe Southern blots of human genomic DNA. A 1.6-kb Eco RI fragment (designated hv3005/E1.6) was found to hybridize with only one band in Eco RI-digested DNA, and with two major bands in Bam HI-digested DNA. Importantly, the sizes of the latter two bands were indistinguishable from the corresponding Bam HI fragment sizes of the isolated hv3005 clone and the isolated 1.9III clone, respectively. Population and family studies with the hv3005/E1.6 probe revealed five different hybridization patterns of these two characteristic bands, which defined nine possible genotypes for two human Ig Vh gene loci. Together the data demonstrate that hv3005/E1.6 is a highly informative probe for an autoantibody-associated Vh gene(s), and should prove useful in elucidating the role of Ig Vh genes in autoimmune diseases.
Images
PMCID: PMC548935  PMID: 2569476
22.  The granulocyte colony stimulating factor pathway regulates autoantibody production in a murine induced model of systemic lupus erythematosus 
Introduction
An NZB-derived genetic locus (Sle2c2) that suppresses autoantibody production in a mouse model of induced systemic lupus erythematosus contains a polymorphism in the gene encoding the G-CSF receptor. This study was designed to test the hypothesis that the Sle2c2 suppression is associated with an impaired G-CSF receptor function that can be overcome by exogenous G-CSF.
Methods
Leukocytes from B6.Sle2c2 and B6 congenic mice, which carry a different allele of the G-CSF receptor, were compared for their responses to G-CSF. Autoantibody production was induced with the chronic graft-versus-host-disease (cGVHD) model by adoptive transfer of B6.bm12 splenocytes. Different treatment regimens varying the amount and frequency of G-CSF (Neulasta®) or carrier control were tested on cGVHD outcomes. Autoantibody production, immune cell activation, and reactive oxygen species (ROS) production were compared between the two strains with the various treatments. In addition, the effect of G-CSF treatment was examined on the production autoantibodies in the B6.Sle1.Sle2.Sle3 (B6.TC) spontaneous model of lupus.
Results
B6.Sle2c2 and B6 leukocytes responded differently to G-CSF. G-CSF binding by B6.Sle2c2 leukocytes was reduced as compared to B6, which was associated with a reduced expansion in response to in vivo G-CSF treatment. G-CSF in vivo treatment also failed to mobilize bone-marrow B6.Sle2c2 neutrophils as it did for B6 neutrophils. In contrast, the expression of G-CSF responsive genes indicated a higher G-CSF receptor signaling in B6.Sle2c2 cells. G-CSF treatment restored the ability of B6.Sle2c2 mice to produce autoantibodies in a dose-dependent manner upon cGVHD induction, which correlated with restored CD4+ T cells activation, as well as dendritic cell and granulocyte expansion. Steady-state ROS production was higher in B6.Sle2c2 than in B6 mice. cGVHD induction resulted in a larger increase in ROS production in B6 than in B6.Sle2c2 mice, and this difference was eliminated with G-CSF treatment. Finally, a low dose G-CSF treatment accelerated the production of anti-dsDNA IgG in young B6.TC mice.
Conclusion
The different in vivo and in vitro responses of B6.Sle2c2 leukocytes are consistent with the mutation in the G-CSFR having functional consequences. The elimination of Sle2c2 suppression of autoantibody production by exogenous G-CSF indicates that Sle2c2 corresponds to a loss of function of G-CSF receptor. This result was corroborated by the increased anti-dsDNA IgG production in G-CSF-treated B6.TC mice, which also carry the Sle2c2 locus. Overall, these results suggest that the G-CSF pathway regulates the production of autoantibodies in murine models of lupus.
doi:10.1186/ar4208
PMCID: PMC3672747  PMID: 23566364
23.  Lupus Nephritis in Asia: Clinical Features and Management 
Kidney Diseases  2015;1(2):100-109.
Background
Lupus nephritis (LN) is a common and severe organ involvement manifesting itself in systemic lupus erythematosus (SLE). There is a considerable difference in prevalence, severity, treatment response and outcomes between Asian LN patients and LN patients from other racial backgrounds.
Summary
Asian SLE patients have a higher prevalence of LN than Caucasian SLE patients and often present with a more severe disease. Increasing data from genetic studies, accompanied by progress in high-throughput genotyping, have advanced our knowledge about genetic predispositions that might partly contribute to the clinical variations observed. Corticosteroids combined with either cyclophosphamide (CYC) or mycophenolic acid (MPA) is the current standard-of-care induction regimen for severe LN irrespective of race or ethnicity. However, the preference for MPA or CYC, and possibly the optimum dose for MPA, is influenced by the patient's origin. Also, there is an insufficient evidence base for reduced-dose intravenous CYC in Asian patients. Health economics and access to prompt diagnosis and treatment are still challenging issues in some Asian regions. The former represents a significant obstacle limiting the access of patients to MPA despite the proven efficacy of the drug as an induction agent and its superiority over azathioprine (AZA) in preventing disease flares when used for long-term maintenance immunosuppression. Calcineurin inhibitors such as tacrolimus deserve further investigation in view of their additional effect on podocytes by reducing proteinuria and the promising data from Asian patients. Despite considerable advances in the clinical management of LN over the past few decades with resultant improvements in patients' outcomes, there are still knowledge gaps and unmet clinical needs. Asia has made substantial contributions to the evidence base that guides clinical management and continues to offer invaluable opportunities for research pursuits.
Key Messages
Treatment responses and clinical outcomes in Asian patients with LN compare favorably with patients from other parts of the world. The prevention and treatment of infective complications remain significant challenges in managing LN in Asia.
Facts from East and West
(1) The prevalence of SLE is lower among Caucasians than other ethnicities. A higher prevalence is observed among Asians and African Americans, while the highest prevalence is found in Caribbean people. The prevalence of LN in Asian SLE patients is much higher than in Caucasians as well. However, the 10-year renal outcome and renal survival rate appear to be better in Asians. (2) Polymorphisms of genes involved in the immune response, such as Fcγ receptor, integrin alpha M, TNF superfamily 4, myotubularin-related protein 3 and many others, might be partly responsible for the differences in prevalence between the different ethnic groups. European ancestry was shown to be associated with a decrease in the risk of LN even after adjustment for genes most associated with renal disease. (3) Access to health care is a key determinant of disease progression, treatment outcome and the management of complications such as infections, particularly in South Asia, and might also explain disparities between clinical outcomes. (4) The efficacy of low-dose CYC combined with corticosteroids for induction treatment of LN was proved in European Caucasian patients. This treatment is also used in Asia, although no formal evaluation of efficacy and safety in comparison with other treatment regimens exists in this population. The efficacy of mycophenolate mofetil (MMF) is similar to that of CYC, and similar between Asians and Caucasians. MMF may be more effective than CYC in inducing response in high-risk populations such as African American or Hispanic patients. MMF might cause less infection-related events in Asians, but its high cost prevents broader usage at present. (5) For maintenance therapy, corticosteroid combined with AZA or MMF is used worldwide, with a broadly similar efficacy of both treatments, although there are data suggesting that in high-risk populations (e.g. African Americans) MMF may be more effective in preventing renal flares. AZA is often preferred in Asia due to economic constraints and because of its safety in pregnancy. (6) Alternative therapies under investigation include rituximab, which might be more efficient in Caucasians, as well as belimumab. Recent Japanese and Chinese studies have indicated a potential benefit of tacrolimus as a substitute for or in addition to CYC or MMF (dual or triple immunosuppression). Mizoribine is used in Japan exclusively.
doi:10.1159/000430458
PMCID: PMC4934808  PMID: 27536670
Asians; Azathioprine; Cyclophosphamide; Lupus nephritis; Mycophenolate
24.  Elevated Serum Levels of Interferon-Regulated Chemokines Are Biomarkers for Active Human Systemic Lupus Erythematosus 
PLoS Medicine  2006;3(12):e491.
Background
Systemic lupus erythematosus (SLE) is a serious systemic autoimmune disorder that affects multiple organ systems and is characterized by unpredictable flares of disease. Recent evidence indicates a role for type I interferon (IFN) in SLE pathogenesis; however, the downstream effects of IFN pathway activation are not well understood. Here we test the hypothesis that type I IFN-regulated proteins are present in the serum of SLE patients and correlate with disease activity.
Methods and Findings
We performed a comprehensive survey of the serologic proteome in human SLE and identified dysregulated levels of 30 cytokines, chemokines, growth factors, and soluble receptors. Particularly striking was the highly coordinated up-regulation of 12 inflammatory and/or homeostatic chemokines, molecules that direct the movement of leukocytes in the body. Most of the identified chemokines were inducible by type I IFN, and their levels correlated strongly with clinical and laboratory measures of disease activity.
Conclusions
These data suggest that severely disrupted chemokine gradients may contribute to the systemic autoimmunity observed in human SLE. Furthermore, the levels of serum chemokines may serve as convenient biomarkers for disease activity in lupus.
A comprehensive survey of the serologic proteome in human SLE suggests that severely disrupted chemokine gradients may contribute to the systemic autoimmunity observed.
Editors' Summary
Background.
The term “lupus,” meaning wolf in Latin, is often used as an abbreviation for the disease systemic lupus erythematosus (SLE). The name may have been given because some people with SLE have a rash that slightly resembles a wolf's face. The condition affects around 50 to 100 people per 100,000, and is much more common in women than men. SLE is a complicated disease that comes about when antibodies inappropriately attack the body's own connective tissues, although it is not known why this happens. Symptoms vary between different people; the disease may get better and then worse, without explanation; and can affect many different organs including the skin, joints, kidneys, blood cells, and brain and nervous system. SLE is difficult for doctors to diagnose. Although the disease cannot be cured, patients who are diagnosed with SLE can be treated for their symptoms, and the right management can slow progress of the disease. One area of SLE research focuses on finding “molecular markers” (e.g., proteins or other compounds) that could be tested for in the blood. Researchers hope this would help doctors to more accurately diagnose SLE initially, and then also help to track progress in a patient's condition.
Why Was This Study Done?
“Gene expression” is a term meaning the process by which a gene's DNA sequence is converted into the structures and functions of a cell. These investigators had found in previous studies that certain genes were more “highly expressed” in the blood cells of patients with SLE. Some of these genes were already known to be regulated by interferons (a group of proteins, produced by certain blood cells, that are important in helping to defend against viral infections). The investigators performing this study wanted to understand more clearly the role of interferon in SLE and to see whether the genes that are more highly expressed in patients with SLE go on to produce higher levels of protein, which might then provide useful markers for monitoring the condition.
What Did the Researchers Do and Find?
This research project was a “case-control” study, in which the researchers compared the levels of certain proteins in the blood of people who had SLE with the levels in people who did not have the condition. Thirty people were recruited as cases, from a group of patients with SLE who have been under evaluation at Johns Hopkins School of Medicine since 1987. Fifteen controls were recruited from a group of healthy people of similar age and sex as the patients with SLE; everyone involved in the study gave their consent to take part. Blood samples were taken from each individual, and the serum (liquid component of blood) was separated out. The serum levels of 160 different blood proteins were then measured. When comparing levels of blood proteins between the groups, the researchers found that 30 specific proteins were present at higher or lower levels in the SLE-affected patients. Many of these proteins are cytokines, which are regulated by interferons and are involved in the process of “signaling” within the immune system. A few proteins were found at lower levels. Levels of the interferon-regulated proteins were, on average, seen at higher levels in people whose condition was more severe.
What Do These Findings Mean?
These results suggest that patients with SLE are likely to have a very different pattern of regulation of certain proteins within the blood, particularly the proteins involved in signaling within the immune system. The authors propose that these proteins may be involved in the progression of the disease. There is also the possibility that some of these proteins may prove useful in diagnostic tests, or in tests for monitoring how the disease progresses. However, before any such tests could be used in clinical practice, they would need to be further developed and then thoroughly tested in clinical trials.
Additional Information.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0030491
Patient information from the UK National Health Service on systemic lupus erythematosus
Patient handout from the US National Institutes of Health
MedlinePLUS encyclopedia entry on lupus
Information on lupus from the UK Arthritis Research Campaign
doi:10.1371/journal.pmed.0030491
PMCID: PMC1702557  PMID: 17177599
25.  Replicated associations of TNFAIP3, TNIP1 and ETS1 with systemic lupus erythematosus in a southwestern Chinese population 
Arthritis Research & Therapy  2011;13(6):R186.
Introduction
Recent genome-wide and candidate gene association studies in large numbers of systemic lupus erythematosus (SLE) patients have suggested approximately 30 susceptibility genes. These genes are involved in three types of biological processes, including immune complex processing, toll-like receptor function and type I interferon production, and immune signal transduction in lymphocytes, and they may contribute to the pathogenesis of SLE. To better understand the genetic risk factors of SLE, we investigated the associations of seven SLE susceptibility genes in a Chinese population, including FCGR3A, FCGR2A, TNFAIP3, TLR9, TREX1, ETS1 and TNIP1.
Methods
A total of 20 SNPs spanning the seven SLE susceptibility genes were genotyped in a sample of 564 unrelated SLE patients and 504 unrelated healthy controls recruited from Yunnan, southwestern China. The associations of SNPs with SLE were assessed by statistical analysis.
Results
Five SNPs in two genes (TNFAIP3 and ETS1) were significantly associated with SLE (corrected P values ranging from 0.03 to 5.5 × 10-7). Through stratified analysis, TNFAIP3 and ETS1 showed significant associations with multiple SLE subphenotypes (such as malar rash, arthritis, hematologic disorder and antinuclear antibody) while TNIP1 just showed relatively weak association with onset age. The associations of the SNPs in the other four genes were not replicated.
Conclusions
The replication analysis indicates that TNFAIP3, ETS1 and TNIP1 are probably common susceptibility genes for SLE in Chinese populations, and they may contribute to the pathogenesis of multiple SLE subphenotypes.
doi:10.1186/ar3514
PMCID: PMC3334635  PMID: 22087647

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