A susceptibility locus for human systemic lupus erythematosus (hSLE1) on chromosome 2q

Association of BCL2 polymorphisms and the IL19 single nucleotide polymorphism rs2243188 with systemic lupus erythematosus

Objective

Abnormal B cell lymphoma-2 (Bcl-2) and interleukin-19 (IL-19) expression is closely related to systemic lupus erythematosus (SLE) pathogenesis. We aimed to determine whether BCL2 polymorphisms and a single nucleotide polymorphism (SNP) of IL19 are significantly associated with SLE susceptibility and if this is affected by synergism between IL19 and BCL2 genotypes.

Methods

This observational cohort study randomly enrolled 150 patients with SLE and 150 healthy controls. Major BCL2 and IL19 allele and genotype distributions were examined in the two groups. The IL19 SNP rs2243188 was determined using the TaqMan-MGB probe method. The synergistic effect between BCL2 and IL19 and clinical symptoms of SLE was also analyzed.

Results

The distribution of major BCL2 genotypes and common BCL2 alleles, especially for genotypes 191, 193, and 197, differed significantly between patients and controls. A significant difference in the dominant genetic model was also observed between groups, but not in the recessive model. The risk of disease in individuals who carried both 195-bp BCL2 and 138-bp IL19 susceptibility alleles was higher than in those carrying either allele alone.

Conclusions

This preliminary study suggested that BCL2 polymorphisms and the IL19 SNP rs2243188 are closely related to the pathogenesis of SLE.

Whole Exome Sequencing of Patients from Multicase Families with Systemic Lupus Erythematosus Identifies Multiple Rare Variants

In an effort to identify rare alleles associated with SLE, we have performed whole exome sequencing of the most distantly related affected individuals from two large Icelandic multicase SLE families followed by Ta targeted genotyping of additional relatives. We identified multiple rare likely pathogenic variants in nineteen genes co-segregating with the disease through multiple generations. Gene co-expression and protein-protein interaction analysis identified a network of highly connected genes comprising several loci previously implicated in autoimmune diseases. These genes were significantly enriched for immune system development, lymphocyte activation, DNA repair, and V(D)J gene recombination GO-categories. Furthermore, we found evidence of aggregate association and enrichment of rare variants at the FAM71E1/EMC10 locus in an independent set of 4,254 European SLE-cases and 4,349 controls. Our study presents evidence supporting that multiple rare likely pathogenic variants, in newly identified genes involved in known disease pathogenic pathways, segregate with SLE at the familial and population level.

Autoantibodies persist in relatives to systemic lupus erythematosus patients during 12 years follow-up

Background

Systemic lupus erythematosus (SLE) is an autoimmune disease with presence of autoantibodies and characteristic multi-organ involvement. Relatives of SLE patients have an increased risk of autoantibody production and autoimmune diseases.

Methods

In 2001, 226 first degree relatives (FDRs) of a population-based cohort of SLE patients were examined for the prevalence of autoantibodies and self-reported health complaints. In 2013, 143 FDRs were re-investigated and deceased’s medical records were examined.

Results

Participants and non-participants were comparable regarding baseline characteristics, while deceased FDRs were older than participants, but with comparable ANA status. ANA status at baseline correlated to ANA status at follow-up. At follow-up, two FDRs reported SLE and 15 FDRs other autoimmune diseases. No observation at baseline alone could predict self-reported health. During follow-up 33 died at median age 76 years. Three deceased FDRs were diagnosed with an autoimmune disease.

Conclusion

The study showed that FDRs of SLE patients have an increased prevalence of ANA compared to healthy controls. The prevalence increased during follow-up, and ANA positive FDRs at baseline were prone to be ANA positive at follow-up. ANA positive FDRs had more self-reported autoimmune diseases, including SLE and rheumatoid arthritis, than reported from other population-based investigations.

Association between PDCD1 Gene Polymorphisms and Risk of Systemic Lupus Erythematosus in Three Main Ethnic Groups of the Malaysian Population

The programmed cell death 1 (PDCD1) gene encodes for the PD-1 (programmed death 1) molecule, which negatively regulates self-reactive T- and B-cells in the maintenance of peripheral tolerance. A previous report had shown the development of lupus-like phenotypes in PD-1-deficient C57BL/6 mice, was suggestive to the role of PDCD1 in predisposing to systemic lupus erythematosus (SLE). Hence, we aimed to investigate the association between PDCD1 and SLE susceptibility in the Malaysian population. A TaqMan-based real-time PCR was employed to screen for PD1.1, PD1.3, PD1.5 and PD1.6 in both SLE and healthy control groups of 200 samples each. The observed frequency for PD1.5C/C genotype was significantly higher in Indian SLE patients and Malay controls (p < 0.01). On the other hand, the PD1.5C/T genotype might predispose the Malays to SLE, but confer a protective effect among the Indians (p < 0.01). The PD1.1, PD1.3 and PD1.6 were, however, not correlated to genetic predisposition of SLE in our Malaysian population. In conclusion, PD1.5 variant was significantly associated to SLE susceptibility in our Malaysian cohort. Our failure in replicating the association between other investigated PDCD1 variants and risk of getting SLE might due to ethnic and geographic variations in the distribution of these genetic variants.

A study on the association of autoantibodies, chemokine, and its receptor with disease activity in systemic lupus erythematosus in North Indian population

Systemic lupus erythematosus (SLE) is a chronic and complex autoimmune disease characterized by the production of autoantibodies against a spectrum of nuclear antigens. RANTES and its receptor CCR5 have been associated with the pathogenesis of SLE. The objective of this study is to analyze autoantibodies (DNA/RNA), allelic distribution of RANTES and the association of levels of RANTES and its receptor CCR5 in SLE patients in North Indian region. The RANTES-403 and RANTES-28 polymorphism in the promoter region of RANTES gene was studied in 80 patients and 80 healthy controls. The levels of chemokine RANTES, its receptor CCR5, anti-dsDNA, and anti-SSA antibodies levels were determined. Disease activity was assessed with the systemic lupus erythematosus disease activity index (SLEDAI) score. All the parameters were studied for statistical analysis by using t test (graph pad prism) and correlation by SPSS data. PCR-RFLP performed showed 28C/C and the 403G/G genotypes in both patients and controls, but no other genotypes such as 28C/G, 28G/G and 403A/G, 403A/A were found. Patients had higher levels of RANTES (1840.48 ± 739.42 vs. 835.44 ± 70.48 pg/ml; P < 0.0001) and its receptor CCR5 expression (26.49 ± 0.16 vs. 24.72 ± 3.02 %; P < 0.05) compared to controls. The levels of autoantibodies anti-dsDNA and anti-SSA were also higher in patients than controls. The patients showing elevated anti-dsDNA had negative correlation with SLEDAI score (P < 0.05) while borderline patients were not found to be correlated. In case of anti-Ro/anti-SSA antibody levels, the borderline patients showed a moderately significant negative correlation as compared to controls than patients with elevated autoantibody (P < 0.01). The levels of RANTES and CCR5 were also higher in case of patients than controls. But there was no significant correlation of RANTES and CCR5 with disease activity. We were unable to find an association of RANTES polymorphism with SLE in North Indian population in our sample. No significant difference in allele distribution of RANTES-28 and RANTES-403 in the sample of 160 individuals was detected. Of the two autoantibodies studied, anti-Ro/anti-SSA levels in borderline lupus patients appeared as an important parameter for monitoring/diagnosis of lupus patients.

Lack of association between TYK2 and STAT3 genes and Crohn's disease in the Malaysian population

This study aimed to investigate the potential association of TYK2 and STAT3 genes with the susceptibility to Crohn's disease (CD) among Malaysians. DNA samples were obtained from 80 CD patients and 100 healthy controls. Polymerase chain reaction-restriction fragment length polymorphism methods were employed for genotyping, followed by statistical analysis. In our current study, none of the single nucleotide polymorphisms of either TYK2 or STAT3 was statistically associated with the susceptibility to CD in our local population (P > 0.05). In contrast, there was a statistically significant association between the G/G homozygotes of the STAT3 rs2293152 and the healthy control group (χ(2) = 6.229, P < 0.05). In conclusion, our study does not support the role of the TYK2 and STAT3 genes influencing CD susceptibility.

TYK2 rs34536443 polymorphism is associated with a decreased susceptibility to endometriosis-related infertility

INTRODUCTION

Tyrosine kinase 2 gene (TYK2) is part of the janus kinase (JAK) that binds to the type I interferon-α receptor (IFNAR) on the cell surface of IFN-producing cells, and have crucial importance in the etiology of autoimmune and inflammatory diseases. Many polymorphisms of the TYK2 gene have been identified, and recently, a number of case-control studies were conducted to investigate the association of these polymorphisms with autoimmune and inflammatory diseases, with conflicting results. Based on these observations, we hypothesized that the TYK2 polymorphisms (rs34536443, rs2304256, rs280523, rs12720270 and rs12720356) might be involved in the pathogenesis of endometriosis and/or infertility.

METHODS

Genetic association study comprising 275 infertile women with endometriosis, 92 women with idiopathic infertility and 307 fertile women as controls. TYK2 polymorphisms were identified by TaqMan PCR. Genotype distribution, allele frequency and haplotype analysis of the TYK2 polymorphisms were performed. A p-value <0.05 was considered significant.

RESULTS

Single-marker analysis revealed that TYK2 rs34536443 was significantly associated with protection against endometriosis-related infertility, especially in moderate/severe disease (p = 0.002; OR = 0.24, 95% IC = 0.09-0.62). No difference was found considering the infertile group without endometriosis. No associations were found considering rs2304256, rs280523, rs12720270 and rs12720356 either for endometriosis-related infertility group or idiopathic infertility group. Haplotype analysis of five TYK2 polymorphisms identified a haplotype "CTATG" associated with protection against endometriosis-related infertility, especially in moderate/severe disease (p = 0.027).

CONCLUSION

This is the first study to report an association between TYK2 polymorphisms and endometriosis and/or infertility. These findings require replication in other populations but suggest the TYK2 rs34536443 polymorphisms and "CTATG" haplotype can be associated with a decreased susceptibility to endometriosis-related infertility in Brazilian women.

Murine gammaherpesvirus 68 infection protects lupus-prone mice from the development of autoimmunity

Gammaherpesvirus infections, such as those caused by EBV, have been suggested to promote the development of autoimmunity. To test this idea, we infected healthy WT and lupus-prone B6.Sle123 mice with an EBV-related and rodent-specific gammaherpesvirus, γHV68. Although acute γHV68 infection increased autoantibody levels for 4 to 6 wk, latent infection inhibited these responses for 1 y. The inhibition of autoantibody expression was only observed in B6.Sle123 females and not in males, which already displayed lower autoantibody titers. Contrary to the initial hypothesis, infection of young B6.Sle123 mice, both male and female, resulted in suppression of lymphoid activation and expansion and of glomerular inflammation and sclerosis, preserving kidney function. Moreover, γHV68 infection led to reduced autoantibody titers, lymphoid activation, and glomerular inflammation whether lupus-prone females were infected before or during disease manifestation. Finally, γHV68 infection also inhibited autoantibody production in the genetically distinct MRL/lpr lupus-prone mice. Our findings indicate that γHV68 infection strongly inhibits the development and progression of lupus-like disease in mice that spontaneously develop this condition mediating its beneficial effects at the humoral, cellular, and organ levels. The mechanisms by which the virus exerts this down-modulatory action are not yet clear, but appear to operate via reduced activation of dendritic cells, T cells, and B cells. Gammaherpesviruses coevolved with the vertebrate immune systems, establishing lifelong infections in humans and other mammals. Our findings that γHV68 infection prevents rather than exacerbates autoimmunity in mice suggest that infection with gammaherpesviruses may be protective rather than pathological in most individuals.

CTLA-4 gene polymorphism and the risk of systemic lupus erythematosus in the Chinese population

Several variants of CTLA-4 have been reported to be associated with susceptibility systemic lupus erythematosus (SLE); however, findings have been inconsistent across different populations. Using a case-control study design, we have investigated the role of CTLA-4 polymorphism at positions −1661 and −1722 on SLE susceptibility in our Chinese SLE population in central China's Hubei province. Samples were collected from 148 SLE patients and 170 healthy controls. Polymerase chain reaction restriction fragments length polymorphism (PCR-RFLP) was used to analyze the genotypes of the two sites. Statistically significant difference was observed in genotypes for −1722, but not for −1661. The frequency of the T allele on the −1722 SNP was significantly increased in SLE patients: 57.8% versus 40.6% in controls (P < 0.001, OR = 2.002). While the detected C allele frequency in the controls was significantly elevated in comparison to that in the SLE patients (59.4% versus 42.2%). On the contrary, no association was found between SLE and CTLA-4 polymorphism at position −1661.

Single-nucleotide polymorphisms and haplotype of CYP2E1 gene associated with systemic lupus erythematosus in Chinese population

Introduction

Cytochrome P-450 2E1 (CYP2E1) is an important member of the CYP superfamily, which is involved in the metabolism and activation of many low molecular weight toxic compounds. We tried to investigate the possible association of CYP2E1 tag single nucleotide polymorphisms (SNPs) with susceptibility to systemic lupus erythematosus (SLE) in a Chinese Han population.

Methods

The coding and flanking regions of the CYP2E1 gene were scanned for polymorphisms and tag SNPs were selected. A two-stage case-control study was performed to genotype a total of 876 SLE patients and 680 geographically matched healthy controls (265 cases and 288 controls in stage I and 611 cases and 392 controls in stage II). SLE associations of alleles, genotypes and haplotypes were tested by age and sex adjusted logistic regression. The gene transcription quantitation was carried out for peripheral blood mononuclear cell (PBMC) samples from 120 healthy controls.

Results

Tag SNP rs2480256 was found significantly associated with SLE in both stages of the study. The "A" allele was associated with slightly higher risk (odds ratio (OR) = 1.165, 95% confidence interval (CI) 1.073 to 1.265, P = 2.75E-4) and "A/A" genotype carriers were with even higher SLE risk (OR = 1.464 95% CI 1.259 to 1.702, P = 7.48E-7). When combined with another tag SNP rs8192772, we identified haplotype "rs8192772-rs2480256/TA" over presented in SLE patients (OR 1.407, 95% CI 1.182 to 1.675, P = 0.0001) and haplotype "TG" over presented in the controls (OR 0.771, 95% CI 0.667 to 0.890, P = 0.0004). The gene transcription quantitation analysis further proved the dominant effect of rs2480256 as the "A/A" genotype showed highest transcription.

Conclusions

Our results suggest the involvement of CYP2E1 as a susceptibility gene for SLE in the Chinese population.

Systemic lupus erythematosus: association with KIR and SLC11A1 polymorphisms, ethnic predisposition and influence in clinical manifestations at onset revealed by ancestry genetic markers in an urban Brazilian population

Systemic lupus erythematosus (SLE) is an autoimmune disorder of the connective tissue with a wide and heterogeneous spectrum of manifestations, with renal and neurological involvement usually related to worse prognosis. SLE more frequently affects females of reproductive age, and a high prevalence and renal manifestation seem to be associated with non-European ethnicity. The present study aims to investigate candidate loci to SLE predisposition and evaluate the influence of ethnic ancestry in the disease risk and clinical phenotypic heterogeneity of lupus at onset. Samples represented by 111 patients and 345 controls, originated from the city of Belém, located in the Northern Region of Brazil, were investigated for polymorphisms in HLA-G, HLA-C, SLC11A1, MTHFR, CASP8 and 15 KIR genes, in addition to 89 Amerindian samples genotyped for SLC11A1. We also investigated 48 insertion/deletion ancestry markers to characterize individual African, European and Amerindian ancestry proportions in the samples. Predisposition to SLE was associated with GTGT deletion at the SLC11A1 3'UTR, presence of KIR2DS2 +/KIR2DS5 +/KIR3DS1 + profile, increased number of stimulatory KIR genes, and European and Amerindian ancestries. The ancestry analysis ruled out ethnic differences between controls and patients as the source of the observed associations. Moreover, the African ancestry was associated with renal manifestations.

Meta-analysis of TYK2 gene polymorphisms association with susceptibility to autoimmune and inflammatory diseases

The aim of our meta-analysis was to quantitatively summarize the association of TYK2 gene polymorphisms with autoimmune and inflammatory diseases. 11 studies that included data from 21497 cases and 22647 controls were identified. OR was used as a measure of the effect of the association in a fixed/random effect model. Meta-analysis was performed for six TYK2 gene polymorphisms (rs34536443, rs2304256, rs280523, rs280519, rs12720270 and rs12720356). Significant association was found in rs34536443 (C versus G: OR = 0.76, 95% CI = 0.69-0.84, P < 0.00001; GC + CC versus GG: OR = 0.78, 95% CI = 0.68-0.90, P = 0.0005; CC versus GG + GC: OR = 0.76, 95% CI = 0.28-2.05, P = 0.58; CC versus GG: OR = 0.74, 95% CI = 0.27-2.02, P = 0.56; GC versus GG: OR = 0.78, 95% CI = 0.68-0.90, P = 0.0006) and rs2304256 (A versus C: OR = 0.78, 95% CI = 0.70-0.87, P < 0.0001; CA + AA versus CC: OR = 0.69, 95% CI = 0.59-0.81, P < 0.0001; AA versus CC + CA: OR = 0.75, 95% CI = 0.66-1.00, P = 0.05; AA versus CC: OR = 0.64, 95% CI = 0.47-0.86, P = 0.003; CA versus CC: OR = 0.70, 95% CI = 0.60-0.83, P < 0.0001) in TYK2 gene, but not for the other polymorphisms (rs280523, rs280519, rs12720270, and rs12720356). This meta-analysis demonstrates that autoimmune and inflammatory diseases is associated with TYK2 gene rs34536443 and rs2304256 polymorphisms, but not rs280523, rs280519, rs12720270 and rs12720356.

Increased power of mixed models facilitates association mapping of 10 loci for metabolic traits in an isolated population

The potential benefits of using population isolates in genetic mapping, such as reduced genetic, phenotypic and environmental heterogeneity, are offset by the challenges posed by the large amounts of direct and cryptic relatedness in these populations confounding basic assumptions of independence. We have evaluated four representative specialized methods for association testing in the presence of relatedness; (i) within-family (ii) within- and between-family and (iii) mixed-models methods, using simulated traits for 2906 subjects with known genome-wide genotype data from an extremely isolated population, the Island of Kosrae, Federated States of Micronesia. We report that mixed models optimally extract association information from such samples, demonstrating 88% power to rank the true variant as among the top 10 genome-wide with 56% achieving genome-wide significance, a >80% improvement over the other methods, and demonstrate that population isolates have similar power to non-isolate populations for observing variants of known effects. We then used the mixed-model method to reanalyze data for 17 published phenotypes relating to metabolic traits and electrocardiographic measures, along with another 8 previously unreported. We replicate nine genome-wide significant associations with known loci of plasma cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, thyroid stimulating hormone, homocysteine, C-reactive protein and uric acid, with only one detected in the previous analysis of the same traits. Further, we leveraged shared identity-by-descent genetic segments in the region of the uric acid locus to fine-map the signal, refining the known locus by a factor of 4. Finally, we report a novel associations for height (rs17629022, P< 2.1 × 10⁻⁸).

PDCD1 gene polymorphisms in different Mexican ethnic groups and their role in the susceptibility to hypersensitivity pneumonitis

OBJECTIVE

Hypersensitivity pneumonitis (HP) is an immunological disorder caused by antigen exposure in susceptible individuals. The PDCD1 polymorphisms, PD1.3 and PD1.5 have been associated with the susceptibility to inflammatory disorders. This study was conducted to test whether the PD1.3 and PD1.5 polymorphisms are associated with HP in Mexican patients and to explore the distribution of these polymorphisms in different Mexican ethnic groups.

DESIGN AND METHODS

We studied 98 Mexican patients with HP and 92 healthy Mexican controls. Also, 156 healthy Amerindian individuals from two ethnic groups were included (96 Mayans and 60 Mayos). Polymorphisms were determined by TaqMan 5' nuclease assays.

RESULTS

Significant differences in the distribution of the PD1.3 and PD1.5 genotypes between HP patients and healthy Mestizo controls were not found. We observed a significantly different distribution of these polymorphisms in Mexican Mestizos when compared to the Amerindians.

CONCLUSIONS

We found no association between PD1 polymorphism and HP; however the distribution of these polymorphisms was different in Mexican Mestizos and Amerindians.

European population substructure is associated with mucocutaneous manifestations and autoantibody production in systemic lupus erythematosus

OBJECTIVE

To determine whether genetic substructure in European-derived populations is associated with specific manifestations of systemic lupus erythematosus (SLE), including mucocutaneous phenotypes, autoantibody production, and renal disease.

METHODS

SLE patients of European descent (n=1,754) from 8 case collections were genotyped for >1,400 ancestry informative markers that define a north-south gradient of European substructure. Using the Structure program, each SLE patient was characterized in terms of percent Northern (versus percent Southern) European ancestry based on these genetic markers. Nonparametric methods, including tests for trend, were used to identify associations between Northern European ancestry and specific SLE manifestations.

RESULTS

In multivariate analyses, increasing levels of Northern European ancestry were significantly associated with photosensitivity (Ptrend=0.0021, odds ratio for highest quartile of Northern European ancestry versus lowest quartile [ORhigh-low] 1.64, 95% confidence interval [95% CI] 1.13-2.35) and discoid rash (Ptrend=0.014, ORhigh-low 1.93, 95% CI 0.98-3.83). In contrast, increasing levels of Northern European ancestry had a protective effect against the production of anticardiolipin autoantibodies (Ptrend=1.6x10(-4), ORhigh-low 0.46, 95% CI 0.30-0.69) and anti-double-stranded DNA autoantibodies (Ptrend=0.017, ORhigh-low 0.67, 95% CI 0.46-0.96).

CONCLUSION

This study demonstrates that specific SLE manifestations vary according to Northern versus Southern European ancestry. Thus, genetic ancestry may contribute to the clinical heterogeneity and variation in disease outcomes among SLE patients of European descent. Moreover, these results suggest that genetic studies of SLE subphenotypes will need to carefully address issues of population substructure based on genetic ancestry.

Genetic aspects of rheumatic diseases

In this review on the genetic aspects of rheumatic diseases, the approach was taken (i) to discuss, in general, important principles in the identification of susceptibility genes and (ii) to focus on five autoimmune rheumatic diseases that have the characteristics of complex diseases and in which important advances have been made in the identification of the genetic component. A decade ago, most reviews on the genetics of rheumatic diseases focused almost exclusively on a discussion of the human leukocyte antigen (HLA) but in this fast-moving field it is now apparent that genes outside the HLA also contribute to susceptibility. Current hypotheses concerning the pathogenesis of autoimmunity have led to the inclusion of hundreds of genes as potential candidates. Almost any molecule involved in immune recognition, cell interaction, intracellular signalling, cytokine pathways or programmed cell death can be reasonably proposed. The identification of the genes involved in complex diseases will contribute to an understanding of disease mechanisms and disease biology. The disease pathways by which the genes exert their effects or functions could lead to the discovery of new therapeutic targets that may be modulated. An increased understanding of the interactions between genes and environment might also be attained.

Lack of association between tyrosine kinase 2 (TYK2) gene polymorphisms and susceptibility to SLE in a Japanese population

Tyrosine kinase 2 (TYK2) is a type I interferon (IFN) signaling pathway gene and was previously reported to be a risk factor for systemic lupus erythematosus (SLE) in Caucasian populations. In order to test for its genetic association with SLE in a Japanese population, TYK2 single nucleotide polymorphisms (SNPs), rs2304256, rs12720270 and rs280519, were genotyped. A case-control association study was performed in a total of 411 Japanese SLE patients and 467 healthy controls. Linkage disequilibrium (LD) among TYK2 SNPs was examined. According to the data from 94 healthy controls, non-synonymous rs2304256 resulting in Val --> Phe substitution was revealed to be in a LD with rs12720270 and rs280519. Therefore, we further genotyped rs2304256 as a tag SNP in the full sample sets. As a result, no differences in genotype distribution and allelic frequencies of rs2304256 were found between SLE patients and healthy controls. In conclusion, TYK2 is not a genetic risk factor for SLE in a Japanese population. Our result suggests that there is an ethnic difference in the susceptibility genes for SLE.

No evidence for genetic association of interferon regulatory factor 3 in systemic lupus erythematosus

The aim of this study was to determine the potential role of three IRF3 gene polymorphisms (rs2304204, rs7251 and rs2304207) with systemic lupus erythematosus (SLE). Our study population consisted of 610 patients with SLE and 730 healthy controls. All individual were of Spanish Caucasian origin. The IRF3 polymorphisms were genotyped using a PCR system with pre-developed TaqMan allelic discrimination assay. No statistically significant differences were found when allele and genotype distribution of rs2304204, rs7251 and rs2304207 polymorphisms were compared between patients with SLE and controls [overall P values: rs7251, P = 0.06; rs2304204, P = 0.26 and rs2304207, P = 0.36, by chi-squared test on a 3 x 2 contingency table. Overall allelic P values: rs7251, P = 0.8, OR (95%CI) = 1.03 (0.87-1.22); rs2304204, P = 0.2, OR (95%CI) = 1.12 (0.93-1.34) and rs2304207, P = 0.8, OR (95%CI) = 1.02 (0.82-1.26)]. In addition, no evidence of association with haplotypes and clinical features of SLE was found. Our data suggest that the IRF3 polymorphisms do not appear to play a major role in the susceptibility or severity of SLE in a Spanish population.

Kallikrein genes are associated with lupus and glomerular basement membrane-specific antibody-induced nephritis in mice and humans

Immune-mediated nephritis contributes to disease in systemic lupus erythematosus, Goodpasture syndrome (caused by antibodies specific for glomerular basement membrane [anti-GBM antibodies]), and spontaneous lupus nephritis. Inbred mouse strains differ in susceptibility to anti-GBM antibody-induced and spontaneous lupus nephritis. This study sought to clarify the genetic and molecular factors that maybe responsible for enhanced immune-mediated renal disease in these models. When the kidneys of 3 mouse strains sensitive to anti-GBM antibody-induced nephritis were compared with those of 2 control strains using microarray analysis, one-fifth of the underexpressed genes belonged to the kallikrein gene family,which encodes serine esterases. Mouse strains that upregulated renal and urinary kallikreins exhibited less evidence of disease. Antagonizing the kallikrein pathway augmented disease, while agonists dampened the severity of anti-GBM antibody-induced nephritis. In addition, nephritis-sensitive mouse strains had kallikrein haplotypes that were distinct from those of control strains, including several regulatory polymorphisms,some of which were associated with functional consequences. Indeed, increased susceptibility to anti-GBM antibody-induced nephritis and spontaneous lupus nephritis was achieved by breeding mice with a genetic interval harboring the kallikrein genes onto a disease-resistant background. Finally, both human SLE and spontaneous lupus nephritis were found to be associated with kallikrein genes, particularly KLK1 and the KLK3 promoter, when DNA SNPs from independent cohorts of SLE patients and controls were compared. Collectively, these studies suggest that kallikreins are protective disease-associated genes in anti-GBM antibody-induced nephritis and lupus.

Association of programmed cell death 1 polymorphisms and systemic lupus erythematosus: a meta-analysis

Programmed cell death 1 (PDCD1 or PD1) polymorphisms have been inconsistently reported to be associated with systemic lupus erythematosus (SLE). The aim of this study was to explore whether the PDCD1 polymorphisms confer a susceptibility to SLE and lupus nephritis (LN). We conducted a meta-analysis on the association of PDCD1 polymorphisms with SLE in overall and specific ethnic populations. A total of 15 separate comparisons were included in this meta-analysis consisting of nine Europeans, two Latin Americans, two Africans, one Asian and one unknown participant. In subgroup analysis, the PD1.3A allele was significantly associated with SLE in Latin Americans (OR = 3.073, 95% CI = 1.416-6.461, P = 0.003), but not in patients of European and African decent. The PD1.3A allele was a risk factor for LN in European descendants (OR = 2.207, 95% CI = 1.488-3.467, P < 0.001). The PD1.5C allele was a risk factor for SLE in Europeans (OR = 1.297, 95% CI = 1.024-1.643, P = 0.031). In conclusion, this meta-analysis demonstrated an association of the PD1.3A allele with LN in European and SLE in Latin-American populations. Furthermore, the PD1.5C allele was associated with SLE susceptibility in Europeans.

Activation of mammalian target of rapamycin controls the loss of TCRzeta in lupus T cells through HRES-1/Rab4-regulated lysosomal degradation

Persistent mitochondrial hyperpolarization (MHP) and enhanced calcium fluxing underlie aberrant T cell activation and death pathway selection in systemic lupus erythematosus. Treatment with rapamycin, which effectively controls disease activity, normalizes CD3/CD28-induced calcium fluxing but fails to influence MHP, suggesting that altered calcium fluxing is downstream or independent of mitochondrial dysfunction. In this article, we show that activity of the mammalian target of rapamycin (mTOR), which is a sensor of the mitochondrial transmembrane potential, is increased in lupus T cells. Activation of mTOR was inducible by NO, a key trigger of MHP, which in turn enhanced the expression of HRES-1/Rab4, a small GTPase that regulates recycling of surface receptors through early endosomes. Expression of HRES-1/Rab4 was increased in CD4(+) lupus T cells, and in accordance with its dominant impact on the endocytic recycling of CD4, it was inversely correlated with diminished CD4 expression. HRES-1/Rab4 overexpression was also inversely correlated with diminished TCRzeta protein levels. Pull-down studies revealed a direct interaction of HRES-1/Rab4 with CD4 and TCRzeta. Importantly, the deficiency of the TCRzeta chain and of Lck and the compensatory up-regulation of FcepsilonRIgamma and Syk, which mediate enhanced calcium fluxing in lupus T cells, were reversed in patients treated with rapamcyin in vivo. Knockdown of HRES-1/Rab4 by small interfering RNA and inhibitors of lysosomal function augmented TCRzeta protein levels in vitro. The results suggest that activation of mTOR causes the loss of TCRzeta in lupus T cells through HRES-1/Rab4-dependent lysosomal degradation.

Patients with familial and sporadic onset SLE have similar clinical profiles but vary profoundly by race

Few large, multi-ethnic studies have examined the clinical and serologic differences between familial and sporadic SLE patients. Understanding these similarities and differences is critical for interpreting genetic studies and developing therapeutic strategies. We compiled information on 1915 patients with SLE in a large multi-racial cohort, including general demographics, pedigree structure and the specific American College of Rheumatology (ACR) criteria met. One patient was randomly selected from each multiplex family for analysis, yielding 554 European-Americans (EA), 373 African-Americans (AA), 193 Hispanics (HI) and 237 patients of other of mixed races. When comparing familial and sporadic patients stratified by race, lupus erythematosus (LE) cells and arthritis were increased in white familial cases ( P = 5.5 × 10−6 and P = 0.028, respectively), but no other significant differences between familial and sporadic patients were found. We found that there were profound differences in clinical profiles between races. For example, photosensitivity and malar rash were decreased in AA ( P = 1.3 × 10−13 and 1.4 × 10−7, respectively), whereas discoid rash was increased in AA ( P = 5.5×10−6). EA had significantly less renal disease ( P = 5.4×10−13), proteinuria ( P = 4 × 10−12) and anti-Sm ( P = 1.7 × 10−12) than AA or HI. We, therefore, conclude that familial and sporadic onset patients may be treated similarly with respect to clinical and genetic studies.

Promoter polymorphisms in the IRF3 gene confer protection against systemic lupus erythematosus

In order to identify a novel candidate gene in systemic lupus erythematosus (SLE), we analysed a panel of six genes encoding molecules involved in the type I interferon (IFN) system. We first identified variants in the five genes related to type I IFN pathway by sequencing. Genotyping of a panel of eight selected single-nucleotide polymorphisms (SNPs) in six candidate genes ( TLR9, MYD88, IRF3, IRF7, IFNB1, IFNA17) was performed in 137 patients with SLE and matched with 152 healthy controls using polymerase chain reaction-restriction fragment length polymorphism analysis. In functional assay, quantitative real-time polymerase chain reaction was performed to assess constitutive IRF3 mRNA expression in peripheral blood mononuclear cells from healthy subjects with different IRF3 promoter haplotypes. Among eight SNPs genotyped, an IRF3 SNP at –925 was found to be associated with SLE after correction for multiple tests (corrected P = 0.016). Of total five IRF3 SNPs genotyped, the promoter IRF3 SNPs –925A/G and –776C/T showed the most significant association with SLE. With regard to –925A/G, the frequency of GG genotype was significantly decreased among SLE patients compared with the control group (1.5% vs. 9.9%; χ2 = 10.0, P = 0.0015, odds ratio 0.12, 95% confidence interval 0.027–0.554). Our experimental data indicated that constitutive IRF3 mRNA expression was significantly lower in cells carrying the minor G-T/G-T haplotype pair compared with those carrying the major A-C haplotype. In conclusion, we showed that the promoter SNPs of the IRF3 gene were significantly associated with resistance against SLE.

General aspects of the genetics of SLE

The application of genetic techniques to the study of systemic lupus erythematosus (SLE) has identified candidate genes with diverse immunological function. There is a growing understanding that susceptibility to SLE is due to a complex interaction of multiple genes and environmental factors, and that many of these may be shared with other autoimmune diseases. In this first of a series of review articles we outline our current understanding of SLE genetics, in particular summarising the results of recent association studies.

TIRAP (MAL) S180L polymorphism is a common protective factor against developing tuberculosis and systemic lupus erythematosus

BACKGROUND AND AIM

The involvement of Toll-like receptor (TLR)-mediated pathways in infectious and autoimmunity has been suggested. The MyD88 adaptor-like (Mal) protein, also known as the TIR domain-containing adaptor protein (TIRAP), is implicated in the TLR2- and TLR4-mediated MyD88-dependent signaling pathway. The aim of this study was to investigate the influence of the functional TIRAP (MAL) S180L polymorphism on tuberculosis (TB) and four autoimmune diseases namely: rheumatoid arthritis (RA), primary Sjögren's syndrome (pSS), systemic lupus erythematosus (SLE) and type 1 diabetes mellitus (T1D).

METHODS

This was a case-control and family based association study in which 1325 individuals from a well-defined Colombian population were involved. TIRAP (MAL) S180L genotyping was done by using a polymerase chain reaction-restriction fragment length polymorphism technique and by direct sequencing.

RESULTS

Leu180 allele was found to be a protective factor against developing TB (odd ratio (OR): 0.53, 95% confidence interval (CI): 0.29-0.97) and SLE (OR: 0.29, 95% CI: 0.14-0.61) while no significant influence on RA, pSS and T1D was observed.

CONCLUSION

These results support the influence of TIRAP (MAL) S180L polymorphism on TB and indicate that TB and SLE might share a common immunogenetic pathway in the innate immune response.

Association of LILRA2 (ILT1, LIR7) splice site polymorphism with systemic lupus erythematosus and microscopic polyangiitis

Leukocyte immunoglobulin-like receptors (LILRs) are inhibitory, stimulatory or soluble receptors encoded within the leukocyte receptor complex. Some LILRs are extensively polymorphic, and exhibit evidence for balancing selection and association with disease susceptibility. LILRA2 (LIR7/ILT1) is an activating receptor highly expressed in inflammatory tissues, and is involved in granulocyte and macrophage activation. In this study, we examined the association of LILRA2 and adjacently located LILRA1 with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and microscopic polyangiitis (MPA). Polymorphism screening detected a LILRA2 SNP (rs2241524 G>A) that disrupts splice acceptor site of intron 6. Case-control association studies on 273 Japanese SLE, 296 RA, 50 MPA and 284 healthy individuals revealed increase of genotype A/A in SLE (12.1%, odds ratio (OR) 1.82, 95% confidence interval (CI) 1.02-3.24, P=0.041) and in MPA (16.0%, OR 2.52, 95% CI 1.07-5.96, P=0.049) compared with healthy individuals (7.0%). The risk allele caused an activation of a cryptic splice acceptor site that would lead to a novel LILRA2 isoform lacking three amino acids in the linker region (Delta 419-421). Flow cytometry indicated that this isoform was expressed on the surface of monocytes. These findings suggested that LILRA2 Delta 419-421 isoform encoded by the splice site SNP may play a role in SLE and MPA.

Familial lupus and antiphospholipid syndrome

The occurrence of systemic lupus erythematosus (SLE) in several members of a family has spurred intense efforts to identify susceptibility genes predisposing to the disease. As a result, a number of candidate association genes in different ethnic groups have been identified, and some genes have been linked to specific lupus manifestations. Particularly where familial disease occurs in childhood, and especially when it occurs prior to puberty, complement deficiencies and other immunologic defects should be explored. Evidence of other forms of autoimmunity, including autoimmune thyroiditis and antiphospholipid syndrome (APS), is common in families with SLE. Familial APS is uncommon in the absence of other thrombophilic defects, but occasionally is seen with apparent autosomal dominant inheritance. Thus far, no firm gene associations have been identified for APS, in part because of the rarity of multiplex families to study. A search for other familial causes of thrombotic disease should be performed when APS occurs in more than one family member.

Current status of lupus genetics

Over the past 40 years more than 100 genetic risk factors have been defined in systemic lupus erythematosus through a combination of case studies, linkage analyses of multiplex families, and case-control analyses of single genes. Multiple investigators have examined patient cohorts gathered from around the world, and although we doubt that all of the reported associations will be replicated, we have probably already discovered many of the genes that are important in lupus pathogenesis, including those encoding human leukocyte antigen-DR, Fcγ receptor 3A, protein tyrosine phosphatase nonreceptor 22, cytotoxic T lymphocyte associated antigen 4, and mannose-binding lectin. In this review we will present what is known, what is disputed, and what remains to be discovered in the world of lupus genetics.

Recent advances in the genetics of autoimmune diseases

Autoimmune diseases in general are complex genetic diseases where genes and environment interact in unknown ways. In recent years technologies have advanced our knowledge and new genes are being identified very rapidly. We can expect that most genes of major importance for the various autoimmune diseases will be discovered in the coming 5 years. The real challenge comes when we try to understand the mechanisms through which these genes confer disease susceptibility and how the interaction with environment takes place such that clinical expression of the disease results.

Association of a CD24 gene polymorphism with susceptibility to systemic lupus erythematosus

OBJECTIVE

To determine the potential role of the CD24 A57V gene polymorphism in systemic lupus erythematosus (SLE).

METHODS

We studied 3 cohorts of Caucasian patients and controls. The Spanish cohort included 696 SLE patients and 539 controls, the German cohort included 257 SLE patients and 317 controls, and the Swedish cohort included 310 SLE patients and 247 controls. The CD24 A57V polymorphism was genotyped by polymerase chain reaction, using a predeveloped TaqMan allele discrimination assay. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

In the Spanish cohort there was a statistically significant difference in the distribution of the CD24 V allele between SLE patients and controls (OR 3.6 [95% CI 2.13-6.16], P < 0.0001). In addition, frequency of the CD24 V/V genotype was increased in SLE patients compared with controls (OR 3.7 [95% CI 2.16-6.34], P < 0.00001). We sought to replicate this association with SLE in a German population and a Swedish population. A similar trend was found in the German group. The CD24 V/V genotype and the CD24 V allele were more frequent in SLE patients than in controls, although this difference was not statistically significant. No differences were observed in the Swedish group. A meta-analysis of the Spanish and German cohorts demonstrated that the CD24 V allele has a risk effect in SLE patients (pooled OR 1.25 [95% CI 1.08-1.46], P = 0.003). In addition, homozygosity for the CD24 V risk allele significantly increased the effect (pooled OR 2.19 [95% CI 1.50-3.22], P = 0.00007).

CONCLUSION

These findings suggest that the CD24 A57V polymorphism plays a role in susceptibility to SLE in a Spanish population.

A Genome-Wide Study of Lupus: Preliminary Analysis and Data Release

Systemic lupus erythematosus (SLE) is a complex autoimmune disease in which genetics is one of the underlying risk factors. Complicating the analysis of SLE is the fact that the phenotype is heterogeneous, with variations in clinical features, and subgroups are associated with a variety of different autoantibodies. Many association studies of candidate genes as well as linkage studies have generated significant results, highlighting the multigenetic component of the disease. Those findings need to be replicated by independent laboratories and many other genes still remain to be identified. Here, we present our findings on the first genome-wide association study performed in 105 Caucasian patients and controls using the Affymetrix NspI array. The SLE patients studied here were all characterized by the presence of autoantibodies against the U1-6 small nuclear ribonucleoprotein antigen spliceosomal complex. Testing each SNP individually for association with disease, we identified 7 markers with an uncorrected P-value < 0.0001. Of those, three were in reported regions of linkage, namely 20p12, 2q37, and 4p15. To increase the power of our study, we included 60 controls corresponding to the parents from the publicly available CEPH families. The analysis of the 165 cases and controls leads to 28 SNPs being associated with an uncorrected P-value < 0.0001.

Contribution of genetic studies in rodent models of autoimmune arthritis to understanding and treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic and potentially debilitating autoimmune disease. While novel therapies have emerged in recent years, disease remission is rarely achieved. RA is a complex trait, and the identifying of its susceptibility and severity genes has been anticipated to generate new targets for therapeutic intervention. However, finding those genes and understanding their function has been a challenging task. Studies in rodent intercrosses and congenics generated from inbred strains have been an important complementary strategy to identify arthritis genes, and understand how they operate to regulate disease. Furthermore, these new rodent arthritis genes will be new targets for therapeutic interventions, and will identify new candidate genes or candidate pathways for association studies in RA. In this review-opinion article I discuss RA genetics, difficulties involved in gene identification, and how rodent models can facilitate (1) the discovery of both arthritis susceptibility and severity genes, (2) studies of gene-environment interactions, (3) studies of gene-gender interactions, (4) epistasis, (5) functional characterization of the specific genes, (6) development of novel therapies and (7) how the information generated from rodent studies will be useful to understanding and potentially treating RA.

MYO9B gene polymorphisms are associated with autoimmune diseases in Spanish population

The aim of the study was to test MYO9B gene polymorphisms for association with three autoimmune diseases, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and celiac disease (CD), in a Spanish population. We analyzed three SNPs (rs2305767, rs1457092, and rs2305764) in a case-control cohort composed of 349 SLE patients, 356 RA patients, 90 CD patients, and 345 healthy controls. All three SNPs showed a consistent increased frequency of the A allele in SLE, RA, and CD patients compared with healthy controls. An association was observed between CD and rs2305764 (p=0.01, OR=2.3), between SLE and rs1457092 (p=0.002, OR=1.4), and between RA and rs1457092 (p=0.02, OR=1.3). The three autoimmune diseases combined showed significant association with rs1457092 and rs2305764 and with the AAA haplotype (p haplotype=0.005, OR=1.3). Our data demonstrate consistent association with the A allele and AAA haplotype of three SNPs in the MYO9B gene, which were previously reported to be associated with CD in the Dutch population. This suggests that genetic variation in MYO9B is associated with CD, SLE, and RA and that MYO9B is a general risk factor for autoimmunity.

Association of IRF5 in UK SLE families identifies a variant involved in polyadenylation

Results from two studies have implicated the interferon regulatory gene IRF5 as a susceptibility gene in systemic lupus erythematosus (SLE). In this study, we conducted a family-based association analysis in 380 UK SLE nuclear families. Using a higher density of markers than has hitherto been screened, we show that there is association with two SNPs in the first intron, rs2004640 (P = 3.4 x 10(-4)) and rs3807306 (P = 4.9 x 10(-4)), and the association extends into the 3'-untranslated region (UTR). There is a single haplotype block encompassing IRF5 and we show for the first time that the gene comprises two over-transmitted haplotypes and a single under-transmitted haplotype. The strongest association is with a TCTAACT haplotype (T:U = 1.92, P = 5.8 x 10(-5)), which carries all the over-transmitted alleles from this study. Haplotypes carrying the T alleles of rs2004640 and rs2280714 and the A allele of rs10954213 are over-transmitted in SLE families. The TAT haplotype shows a dose-dependent relationship with mRNA expression. A differential expression pattern was seen between two expression probes located each side of rs10954213 in the 3'-UTR. rs10954213 shows the strongest association with RNA expression levels (P = 1 x 10(-14)). The A allele of rs10954213 creates a functional polyadenylation site and the A genotype correlates with increased expression of a transcript variant containing a shorter 3'-UTR. Expression levels of transcript variants with the shorter or longer 3'-UTRs are inversely correlated. Our data support a new mechanism by which an IRF5 polymorphism controls the expression of alternate transcript variants which may have different effects on interferon signalling.

Association of PDCD1 genetic variation with risk and clinical manifestations of systemic lupus erythematosus in a multiethnic cohort

We evaluated the roles of five single-nucleotide polymorphisms (SNPs) within PDCD1, and haplotypes defined by these SNPs, for the development of systemic lupus erythematosus (SLE) and specific sub-phenotypes (nephritis, antiphospholipid antibody positive, arthritis and double-stranded DNA positive) within a multiethnic US cohort of 1036 patients. Family based analyses were performed using 844 simplex families from four ethnic groups (Caucasian, Asian, Hispanic and African American). Subjects were genotyped for five 'tag' SNPs (selected from 15) to provide complete genetic information in all main ethnic groups. We employed transmission disequilibrium testing to assess risk for SLE by allele or haplotype, and multiple logistic regression analysis of SLE cases to examine associations with specific sub-phenotypes. In family based analyses, a haplotype containing the PD1.3A allele was significantly associated with SLE susceptibility among Caucasian families (P=0.01). Among Hispanic families, two novel SNPs were associated with SLE risk (P=0.005 and 0.01). In multivariate logistic regression analyses, five haplotypes were associated with specific sub-phenotypes among the different ethnic groups. These results suggest that PDCD1 genetic variation influences the risk and expression of SLE and that these associations vary according to ethnic background.

A dinucleotide deletion in CD24 confers protection against autoimmune diseases

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 (P1527^del) 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 P1527^del 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.

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.

Genetic association between the PRKCH gene encoding protein kinase Ceta isozyme and rheumatoid arthritis in the Japanese population

OBJECTIVE

Analyses of families with rheumatoid arthritis (RA) have suggested the presence of a putative susceptibility locus on chromosome 14q21-23. This large population-based genetic association study was undertaken to examine this region.

METHODS

A 2-stage case-control association study of 950 unrelated Japanese patients with RA and 950 healthy controls was performed using >400 gene-based common single-nucleotide polymorphisms (SNPs).

RESULTS

Multiple SNPs in the PRKCH gene encoding the eta isozyme of protein kinase C (PKCeta) showed significant single-locus disease associations, the most significant being SNP c.427+8134C>T (odds ratio 0.72, 95% confidence interval 0.62-0.83, P = 5.9 x 10(-5)). Each RA-associated SNP was consistently mapped to 3 distinct regions of strong linkage disequilibrium (i.e., linkage disequilibrium or haplotype blocks) in the PRKCH gene locus, suggesting that multiple causal variants influence disease susceptibility. Significant SNPs included a novel common missense polymorphism of the PRKCH gene, V374I (rs2230500), which lies within the ATP-binding site that is highly conserved among PKC superfamily members. In circulating lymphocytes, PRKCH messenger RNA was expressed at higher levels in resting T cells (CD4(+) or CD8(+)) than in B cells (CD19(+)) or monocytes (CD14(+)) and was significantly down-regulated through immune responses.

CONCLUSION

Our results provide evidence of the involvement of PRKCH as a susceptibility gene for RA in the Japanese population. Dysregulation of PKCeta signal transduction pathway(s) may confer increased risk of RA through aberrant T cell-mediated autoimmune responses.

Autoimmune diseases in a Danish cohort of 4,866 carriers of constitutional structural chromosomal rearrangements

OBJECTIVE

Constitutional structural chromosomal rearrangements (CSCRs) have facilitated the identification of genes associated with early-onset monogenic disorders and, more recently, genes associated with common and late-onset disorders. In an attempt to find genetic clues to their etiologies, we studied the risk of autoimmune diseases in a Danish cohort of CSCR carriers.

METHODS

We followed up 4,866 CSCR carriers over 71,230 person-years (1980 through 2004) for autoimmune diseases recorded in the Danish Hospital Discharge Register. Standardized incidence ratios (SIRs) and 95% confidence intervals (95% CIs) served as measures of the relative risk. To identify possible candidate loci for autoimmune diseases, the reported chromosomal breakpoints and deletions in CSCR carriers who developed autoimmune diseases were compared with previously suggested loci for these diseases.

RESULTS

The overall risk of any autoimmune disease among CSCR carriers was inconspicuous (SIR 1.2 [95% CI 0.95-1.5]; n = 74 cases observed versus 61.3 expected), but carriers of rearrangements involving chromosomes 2, 19, and 21 were at significantly increased risk. For the specific autoimmune diseases studied, cohort members were at significantly increased risk of Dupuytren's contracture, pernicious anemia, and juvenile rheumatoid arthritis (JRA). Sixteen carriers who developed an autoimmune disease had a chromosomal breakpoint or deletion coinciding with a previously suggested locus, including deletions 18p11, 18q22, and 22q11 associated with JRA.

CONCLUSION

CSCR carriers do not have a generalized predisposition to autoimmune diseases. However, we confirmed a number of reported susceptibility loci for JRA, and we suggest new susceptibility loci on chromosomes 5 and 11 for Dupuytren's contracture, and 19p13 as a possible shared susceptibility locus for a range of autoimmune diseases.

Systemic lupus erythematosus: multiple immunological phenotypes in a complex genetic disease

Systemic lupus erythematosus (SLE) is a complex polygenic autoimmune disease characterized by the presence of anti-nuclear autoantibodies (ANAs) that are often detectable years prior to the onset of clinical disease. The disease is associated with a chronic activation of the immune system, with the most severe forms progressing to inflammatory damage that can impact multiple organ systems in afflicted individuals. Current therapeutic strategies poorly control disease manifestations and are generally immunosuppressive. Recent studies in human patient populations and animal models have associated elements of the innate immune system and abnormalities in the immature B lymphocyte receptor repertoires with disease initiation. A variety of cytokines, most notably type I interferons, play important roles in disease pathogenesis and effector mechanisms. The genetic basis for disease susceptibility is complex, and analyses in humans and mice have identified multiple susceptibility loci, several of which are located in genomic regions that are syntenic between humans and mice. The complexities of the genetic interactions that mediate lupus have been investigated in murine model systems by characterizing the progressive development of disease in strains expressing various combinations of susceptibility alleles. These analyses indicate that genetic epistasis dramatically impact disease development and support the feasibility of identifying molecular pathways that can suppress disease progression without completely impairing normal immune function.

No evidence of association between genetic variants of the PDCD1 ligands and SLE

PDCD1, an immunoreceptor involved in peripheral tolerance has previously been shown to be genetically associated with systemic lupus erythematosus (SLE). PDCD1 has two ligands whose genes are located in close proximity on chromosome 9p24. Our attention was drawn to these ligands after finding suggestive linkage to a marker (gata62f03, Z=2.27) located close to their genes in a genome scan of Icelandic families multiplex for SLE. Here, we analyse Swedish trios (N=149) for 23 single nucleotide polymorphisms (SNPs) within the genes of the PDCD1 ligands. Initially, indication of association to eight SNPs was observed, and these SNPs were therefore also analysed in Mexican trios (N=90), as well as independent sets of patients and controls from Sweden (152 patients, 448 controls) and Argentina (288 patients, 288 controls). We do not find support for genetic association to SLE. This is the first genetic study of SLE and the PDCD1 ligands and the lack of association in several cohorts implies that these genes are not major risk factors for SLE.