Meta-analysis of genome-wide linkage studies of systemic lupus erythematosus

HLA-DR genotypes in patients with systemic lupus erythematosus in Taiwan

BACKGROUND

Different human leukocyte antigen (HLA)-DR genotypes have been known to be associated with the risk of development of systemic lupus erythematosus (SLE) in different populations, although Lu et al. have reported previously that no correlation exists between the HLA-DR genotype and disease manifestation in SLE patients in Taiwan. We investigated the effects different HLA-DR genotypes had on SLE incidence in Taiwanese patients as to whether risk alleles were associated with different clinical manifestations, and the effects risk alleles had on the age of disease onset.

METHODS

Two hundred thirty-four SLE patients and 346 healthy controls were enrolled. HLA-DR genotyping was performed with the HLA FluoGene DRDQ kit for each subject. Chi-square tests and t tests were performed for statistical analysis.

RESULTS

HLA-DR2 was significantly more frequently found in SLE patients than in controls (odds ratio [OR] = 2.05, 95% CI, 1.44-2.92, p < 0.001). Notably, HLA-DR6 appeared to trend toward negative correlation with SLE, whereas HLA-DR8 appeared to trend toward positive correlation. HLA-DR2 patients had an earlier onset of disease as well as a higher prevalence of oral ulcer, avascular necrosis of bone, and renal involvement (lupus nephritis).

CONCLUSION

HLA-DR2 was associated with SLE susceptibility in this Taiwanese population as well as lower age of disease onset and more severe clinical manifestations.

The Role of Genetic Risk Factors in Pathogenesis of Childhood-Onset Systemic Lupus Erythematosus

The pathogenesis of childhood-onset systemic lupus erythematosus (cSLE) is complex and not fully understood. It involves three key factors: genetic risk factors, epigenetic mechanisms, and environmental triggers. Genetic factors play a significant role in the development of the disease, particularly in younger individuals. While cSLE has traditionally been considered a polygenic disease, it is now recognized that in rare cases, a single gene mutation can lead to the disease. Although these cases are uncommon, they provide valuable insights into the disease mechanism, enhance our understanding of pathogenesis and immune tolerance, and facilitate the development of targeted treatment strategies. This review aims to provide a comprehensive overview of both monogenic and polygenic SLE, emphasizing the implications of specific genes in disease pathogenesis. By conducting a thorough analysis of the genetic factors involved in SLE, we can improve our understanding of the underlying mechanisms of the disease. Furthermore, this knowledge may contribute to the identification of effective biomarkers and the selection of appropriate therapies for individuals with SLE.

HLA-DRB1*04 as a Risk Allele to Systemic Lupus Erythematosus and Lupus Nephritis in the Malay Population of Malaysia

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease afflicting multiple organs. Lupus nephritis (LN) is a serious complication of SLE and remains a major cause of mortality and morbidity. Curative therapy remains unavailable as etiology from genetic and environmental factors is still unclear. The present study was conducted to elucidate the link between HLA-DRB1 gene polymorphisms with SLE and LN through clinical and laboratory/biological presentations in a population of Malaysian Malay females with SLE. A total of 100 Malay female SLE patients inclusive of 70 SLE patients without LN and 30 patients with LN were included in this study. HLA-DRB1 allele examination in SLE patients was performed using PCR-SSO, and the alleles' frequencies were compared with 951 publicly available datasets representing Malay healthy controls in Malaysia. Cytokines and free radical levels were detected by ELISA and bead-based multiplexed Luminex assays. The association between HLA-DRB1 alleles with clinical and serological manifestations and immune mediators was analyzed using different statistical approaches whenever applicable. Our study showed that HLA-DRB1^*0405, HLA-DRB1^*1502, and HLA-DRB1^*1602 were associated with the increased risk of SLE while HLA-DRB1^*1201 and HLADRB1^*1202 alleles were associated with a lower risk of SLE development. Furthermore, HLA-DRB1^*04 showed significant association to LN and arthritis while HLA-DRB1^*15 was significantly associated with oral ulcer in Malay SLE patients. Association analysis of HLA-DRB1^*04 with clinical and biological factors revealed that HLA-DRB1^*04 was significantly associated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, anti-nuclear antibody (ANA), C-reactive protein (CRP) in the blood, and total protein in the urine. SLE carriers with the HLA-DRB1^*04 allele were significantly correlated to the increased levels of cytokines (IFN-y, GM-CSF, IL-17F, IL-18, IL-21, and VEGF) and were significantly showing negative correlation to IL-5 and free radicals (LPO and catalase enzyme) levels compared to SLE carriers without HLA-DRB1^*04 allele. The results suggested that disease severity in SLE may be determined by HLA-DRB1 alleles. The risk of HLA-DRB1^*04 allele with LN was supported by the demonstration of an intense inflammatory response in Malay SLE patients in Malaysia. More studies inclusive of a larger and multiple SLE cohorts in the future are warranted to validate these findings.

Does MHC heterozygosity influence microbiota form and function?

MHC molecules are essential for the adaptive immune response, and they are the most polymorphic genetic loci in vertebrates. Extreme genetic variation at these loci is paradoxical given their central importance to host health. Classic models of MHC gene evolution center on antagonistic host-pathogen interactions to promote gene diversification and allelic diversity in host populations. However, all multicellular organisms are persistently colonized by their microbiota that perform essential metabolic functions for their host and protect from infection. Here, we provide data to support the hypothesis that MHC heterozygote advantage (a main force of selection thought to drive MHC gene evolution), may operate by enhancing fitness advantages conferred by the host’s microbiome. We utilized fecal 16S rRNA gene sequences and their predicted metagenome datasets collected from multiple MHC congenic homozygote and heterozygote mouse strains to describe the influence of MHC heterozygosity on microbiome form and function. We find that in contrast to homozygosity at MHC loci, MHC heterozygosity promotes functional diversification of the microbiome, enhances microbial network connectivity, and results in enrichment for a variety of microbial functions that are positively associated with host fitness. We demonstrate that taxonomic and functional diversity of the microbiome is positively correlated in MHC heterozygote but not homozygote animals, suggesting that heterozygote microbiomes are more functionally adaptive under similar environmental conditions than homozygote microbiomes. Our data complement previous observations on the role of MHC polymorphism in sculpting microbiota composition, but also provide functional insights into how MHC heterozygosity may enhance host health by modulating microbiome form and function. We also provide evidence to support that MHC heterozygosity limits functional redundancy among commensal microbes and may enhance the metabolic versatility of their microbiome. Results from our analyses yield multiple testable predictions regarding the role of MHC heterozygosity on the microbiome that will help guide future research in the area of MHC-microbiome interactions.

Soluble MHC class II-driven therapy for a systemic lupus erythematosus murine experimental in vitro and in vivo model

Taking into consideration the multiparametric nature of systemic lupus erythematosus (SLE), the severity and variability of symptoms and the lack of effective therapeutic approaches, this study took advantage of the recently described role of soluble major histocompatibility complex class II (sMHCII) molecules in maintaining tolerance to the organism and attempted to apply sMHCII proteins as a treatment to murine SLE experimental models in vitro as well as in vivo. After breaking tolerance to DNA in vitro, which was accompanied by development of specific anti-dsDNA antibodies, syngeneic or allogeneic sMHCII molecules, purified from healthy mouse serum, could significantly reduce the specific antibody levels and drive the system towards immunosuppression, as assessed by specific marker analysis on T cells and cytokine production by flow cytometry and ELISA, respectively. The in vivo experimental model consisted of pristane-induced SLE symptoms to BALB/c mice, which developed maximal levels of anti-dsDNA 2 months after pristane inoculation. Syngeneic or allogeneic sMHCII administration could alleviate pristane-induced symptoms, significantly decrease specific anti-dsDNA antibody production and develop immunosuppression to the host, as manifested by increase of CD4 + CTLA-4 +  and CD4 + CD25 +  cell populations in the spleen. Thus, the results presented in this study introduced the ability of sMHCII proteins to suppress specific autoantigen response, opening new areas of research and offering novel therapeutic approaches to SLE with expanding features to other autoimmune diseases.

Prevalence, severity, and clinical features of acute and chronic pancreatitis in patients with systemic lupus erythematosus

Pancreatitis is a rare, life-threatening complication of systemic lupus erythematosus (SLE). This study aimed to describe the clinical features of acute pancreatitis (AP) and chronic pancreatitis (CP) in patients with SLE. Data of patients who fulfilled the revised criteria of the American Rheumatism Association for diagnosis of SLE were retrospectively analyzed. SLE activity was graded according to the SLE Disease Activity Index. Logistic regression analysis was conducted to find out independent associations. Survival rates were estimated by using Kaplan-Meier plots. This study included 5665 SLE patients admitted between January 1983 and January 2014, of whom 52 patients were diagnosed with pancreatitis. Pancreatitis prevalence in SLE patients was 0.92 % (52/5665). AP (0.8 %, 46/5665) was more prevalent than CP (0.1 %, 6/5665), presented mostly during active SLE, and affected more organs. Hypertriglyceridemia occurred in 76.9 % of AP patients and in none of the CP patients. AP patients were divided into severe (n = 10) or mild (n = 20) cases. The average triglyceride level in severe AP cases was higher than that in mild AP cases (P = 0.006), and the mortality rate of lupus-associated AP was 32.6 % (15/46). Concomitant infections and thrombocytopenia were independently associated with poor prognosis (P < 0.001, P = 0.028, respectively). There were significant differences in the clinical manifestations of AP and CP. Patients with severe AP were found to have a higher incidence of concomitant infection and serum triglyceride levels. Concomitant infections and thrombocytopenia were independent risk factors for poor prognosis.

Genome-wide peripheral blood transcriptome analysis of Arab female lupus and lupus nephritis

Systemic lupus erythematosus (lupus) is a genetically heterogeneous autoimmune disorder with an obscure etiology. With 92-94% of human genes exhibiting alternative splicing, gaining insights to such events may lead to better diagnostics. Herein, we explored the genome-wide peripheral blood transcriptome of lupus and its severe form lupus-nephritis (LN) compared to healthy controls (HC). Age/gender/ethnically-matched Arab females were tested using high-density arrays and statistical analysis was carried out using appropriate software. Analysis revealed 15 splice variants that are differentially expressed between lupus/HC and 99 variants between LN/HC (p ≤ 0.05, SI> or ≤ 0.5, Benjamin Hochberg-False discovery rate correction). Comparison between LN/lupus revealed 7 variants that significantly differed in expression. Pathway analysis of differentially spliced-genes postulated 11 significant pathways in lupus and 12 in LN (p<0.05). Analysis of peripheral blood transcriptome possibly revealed signature causative genes that are alternatively spliced, signifying their clinical relevance. Present study is the first to reveal the significance of alternative variants in lupus and LN.

Comprehensive analysis of polymorphisms in the HLA-G 5' upstream regulatory and 3' untranslated regions in Brazilian patients with systemic lupus erythematosus

This study aims to comprehensively analyze human leucocyte antigen (HLA)-G polymorphisms association with susceptibility to systemic lupus erythematosus (SLE) development and clinical manifestations. The HLA-G 5' upstream regulatory region (URR), 3' untranslated region (UTR) and a cytosine deletion at exon 3 (ΔC, HLA-G*0105N allele) were analyzed in 114 SLE patients and 128 healthy controls from North East Brazil. The +3003T>C (rs1707) C allele and the HG010101c extended HLA-G allele were significantly more frequent in SLE patients than healthy controls (+3003C allele frequency: 12% in SLE patients vs 6% in controls; odds ratio (OR), 2.10, 95% confidence interval (CI), 1.06-4.28, P = 0.026; HG010101c frequency: 11.8% in SLE patients and 6.3% in controls; OR, 2.14, 95% CI, 1.01-4.51, P = 0.046) and were associated with susceptibility for disease development. Other polymorphisms were associated with different clinical manifestations. Although HLA-G role in SLE disease is far from being elucidated yet, our association study results along with a systematic review and meta-analysis suggest that HLA-G might be able to slightly modulate the complex SLE phenotype (pooled OR, 1.14, 95% CI, 1.02-1.27, P = 0.021).

Interferon regulatory factor 3 as key element of the interferon signature in plasmacytoid dendritic cells from systemic lupus erythematosus patients: novel genetic associations in the Mexican mestizo population

Many genetic studies have found an association between interferon regulatory factors (IRF) single nucleotide polymorphisms (SNPs) and systemic lupus erythematosus (SLE); however, specific dendritic cell (DC) alterations have not been assessed. The aim of the present study was to address the expression of IRF3 and IRF5 on different DC subsets from SLE patients, as well as their association with interferon (IFN)-α production and novel SNPs. For the genetic association analyses, 156 SLE patients and 272 healthy controls from the Mexican mestizo population were included. From these, 36 patients and 36 controls were included for functional analysis. Two IRF3 SNPs - rs2304206 and rs2304204 - were determined. We found an increased percentage of circulating pDC in SLE patients in comparison to controls (8.04 ± 1.48 versus 3.35 ± 0.8, P = 0.032). We also observed enhanced expression of IRF3 (64 ± 6.36 versus 36.1 ± 5.57, P = 0.004) and IRF5 (40 ± 5.25 versus 22.5 ± 2.6%, P = 0.010) restricted to this circulating pDC subset from SLE patients versus healthy controls. This finding was associated with higher IFN-α serum levels in SLE (160.2 ± 21 versus 106.1 ± 14 pg/ml, P = 0.036). Moreover, the IRF3 rs2304206 polymorphism was associated with increased susceptibility to SLE [odds ratio (OR), 95% confidence interval (CI) = 2.401 (1.187-4.858), P = 0.021] as well as enhanced levels of serum type I IFN in SLE patients who were positive for dsDNA autoantibodies. The IRF3 rs2304204 GG and AG genotypes conferred decreased risk for SLE. Our findings suggest that the predominant IRF3 expression on circulating pDC is a key element for the increased IFN-α activation based on the interplay between the rs2304206 gene variant and the presence of dsDNA autoantibodies in Mexican mestizo SLE patients.

Relationship between Helicobacter pylori infection and vitiligo: a prospective study

BACKGROUND

Helicobacter pylori is a worldwide bacteria that may affect several extra-gastric systems, including the endocrine, hematologic, vascular, respiratory, immune, and skin. Several skin diseases, including chronic urticaria, alopecia areata, psoriasis, and systemic lupus erythematosis have been found to be associated with H. pylori infection.

AIM

To our knowledge, there are no data showing an association between H. pylori and vitiligo. Therefore, in this study, we wanted to evaluate the relationship between H. pylori and vitiligo.

METHODS

This study is a prospective study carried out in our Gastroenterology and Dermatology and Venereology departments of the Ankara Education and Research Hospital (Ankara, Turkey) between July 2013 and December 2013. Seventy-nine consecutive patients with vitiligo and 72 patients with telogen effluvium (TE) were recruited from the dermatology outpatient clinic. A total of 133 patients with vitiligo (n=68) and TE (n=65) [excluding 18 patients who had suspicious urea breath test (UBT) results] were included in the study. All individuals were tested for H. pylori IgG and CagA. Also, a UBT was performed to detect the presence of H. pylori infection.

RESULTS

There were significantly higher rates of H. pylori positivity, H. pylori CagA, and IgG in serum in the vitiligo group than in the TE group (p<0.05). The number of patients with dyspepsia was significantly higher in the vitiligo group than in the TE group. No statistically significant relationship was seen between H. pylori positivity, CagA, H. pylori IgG, dyspepsia, and the Vitiligo Disease Activity score (p>0.05). Also, when patients with vitiligo were divided into localized and generalized types of vitiligo, there was no association between vitiligo involvement pattern and H. pylori positivity, CagA, H. pylori IgG, and dyspepsia (p>0.05).

CONCLUSION

Additional studies are necessary to evaluate the effect of H. pylori eradication on the clinical course of vitiligo. Further studies are also needed to explain the relationship between H. pylori and the pathogenesis of vitiligo.

Relation between HLA typing and clinical presentations in Systemic Lupus Erythematosus patients in Al-Qassim region, Saudi Arabia

BACKGROUND

Systemic lupus erythematosus (SLE) is a disease with diverse clinical presentations due to interaction between genetic and environmental factors. SLE is associated worldwide with polymorphisms at various loci, including the major histocompatibility complex (MHC), although inconsistencies exist among these studies.

AIMS

This study was carried out to investigate, the association of HLA-DRB1, DRB3, DRB4, DRB5, and DQB1 alleles in SLE patients and clinical presentations at Qassim, Saudi Arabia.

METHODS

Fifty one patients with SLE-84.3% of whom had kidney involvement were studied in a case control study for HLA-DRB1, DRB3, DRB4, DRB5, and DQB1.

RESULTS

It was found that DRB3 is a protective gene among Saudi's against SLE, HLA DRB3, HLA DRB1*11 frequency was increased in patients with serositis with a p value of (0.004), (0.047) respectively, increased frequency of HLA DQB1*3 among SLE patients with skin manifestations with a p value of (0.041), the frequency of HLA DRB1*15 alleles was increased among SLE patients with nephritis with a p value of (0.029), the frequency of HLA DRB1*11 among those with hematological manifestations with a p value of (0.03) and the frequency DRB1*10 was found to be increased among SLE patients with neurological manifestations with a p value of (0.002).

CONCLUSION

In contradistinction to what have been found among other populations DRB3 is a protective gene among Saudi's against SLE. No evidence for a role of the HLA-DRB1, DRB4, DRB5, DQB1 alleles. There was an increased HLA DRB3 frequency with serositis, DQB1*3 skin manifestations, HLA DRB1*15 with nephritis, DRB1*10 with hematological manifestations and DRB1*11 with neurological manifestations.

Systemic-lupus-erythematosus-related acute pancreatitis: a cohort from South China

Acute pancreatitis (AP) is a rare but life-threatening complication of SLE. The current study evaluated the clinical characteristics and risk factors for the mortality of patients with SLE-related AP in a cohort of South China. Methods. Inpatient medical records of SLE-related AP were retrospectively reviewed. Results. 27 out of 4053 SLE patients were diagnosed as SLE-related AP, with an overall prevalence of 0.67%, annual incidence of 0.56‰ and mortality of 37.04%. SLE patients with AP presented with higher SLEDAI score (21.70 ± 10.32 versus 16.17 ± 7.51, P = 0.03), more organ systems involvement (5.70 ± 1.56 versus 3.96 ± 1.15, P = 0.001), and higher mortality (37.04% versus 0, P = 0.001), compared to patients without AP. Severe AP (SAP) patients had a significant higher mortality rate compared to mild AP (MAP) (75% versus 21.05%, P = 0.014). 16 SLE-related AP patients received intensive GC treatment, 75% of them exhibited favorable prognosis. Conclusion. SLE-related AP is rare but concomitant with high mortality in South Chinese people, especially in those SAP patients. Activity of SLE, multiple-organ systems involvement may attribute to the severity and mortality of AP. Appropriate glucocorticosteroid (GC) treatment leads to better prognosis in majority of SLE patients with AP.

Biomarkers for systemic lupus erythematosus

The urgent need for lupus biomarkers was demonstrated in September 2011 during a Workshop sponsored by the Food and Drug Administration: Potential Biomarkers Predictive of Disease Flare. After 2 days of discussion and more than 2 dozen presentations from thought leaders in both industry and academia, it became apparent that highly sought biomarkers to predict lupus flare have not yet been identified. Even short of the elusive biomarker of flare, few biomarkers for systemic lupus erythematosus (SLE) diagnosis, monitoring, and stratification have been validated and employed for making clinical decisions. This lack of reliable, specific biomarkers for SLE hampers proper clinical management of patients with SLE and impedes development of new lupus therapeutics. As such, the intensity of investigation to identify lupus biomarkers is climbing a steep trajectory, lending cautious optimism that a validated panel of biomarkers for lupus diagnosis, monitoring, stratification, and prediction of flare may soon be in hand.

Mapping susceptibility gene in systemic lupus erythematosus

Genome-wide association studies have identified many dozen genetic intervals that harbor single-nucleotide polymorphisms (SNPs) showing statistical association with systemic lupus erythematosus. Despite the wealth of data produced, there are limitations of these studies. The causal alleles at a given locus are not identified; only SNP is strong linkage disequilibrium with the putative causative alleles. In order to address identification of the causative SNPs for lupus susceptibility genes, we have initiated a candidate gene study for which more than 40 investigators have contributed patient and control samples. In addition, these investigators have designated SNPs to be placed on a custom array. In this way fine mapping of genetic association findings can occur in order to identify causal alleles. These efforts have thus far benefitted greatly from comparisons of different ethnicities. Work on about ten previously identified associations has been published using this resource. Genome-wide association studies cannot identify rare SNPs or mutations, which may impart greater relative risks than common variants. Much of the genetics of lupus may be from rare variants or mutations. In order to approach this aspect of lupus genetics, next-generation sequencing has begun in which all exons will be sequenced in controls and patients. This effort can also be used to identify causal alleles from association intervals not yet otherwise identified.

Association of the HLA-G gene +3142C>G polymorphism with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease that affects several organs and systems. Its etiology remains unknown, although it is probably multifactorial. The human leukocyte antigen G (HLA-G) is a nonclassic major histocompatibility complex I molecule characterized by restricted expression and low DNA polymorphism. HLA-G plays a role in immunosuppression through different mechanisms. In inflammatory diseases, it has been postulated that HLA-G expression may be a possible mechanism of tissue protection against exacerbated inflammatory response. On the 3' untranslated region (3' UTR) of the HLA-G gene, there is an insertion/deletion polymorphism of 14 bp (rs1704) that was shown to influence the mRNA stability. The influence of this polymorphism in disease susceptibility is controversial. Also in the 3' UTR there is a single nucleotide polymorphism C/G (rs1063320) on the position +3142, at a possible binding site for microRNAs (miRNAs) and having an influence on miRNA affinity. In this study, we analyzed the +3142C>G and the 14 bp polymorphisms in 195 SLE European-derived female patients. Our findings show a significant increase of the +3142G allele frequency among patients as compared with controls (0.58 vs 0.47, P = 0.011). Also, patients presented a higher frequency of the GG genotype (OR = 1.90, 95% CI: 1.08-3.42). Double heterozygotes for the two polymorphisms presented a milder mean systemic lupus erythematosus disease activity index (SLEDAI) than heterozygotes for only one of the variants or non-heterozygous individuals (1.56 vs 3.15 and 3.26, respectively, corrected P = 0.044). These results suggest the involvement of the HLA-G molecule on SLE susceptibility and outcome.

Association of FcgR2a, but not FcgR3a, with inflammatory bowel diseases across three Caucasian populations

BACKGROUND

The Fc receptors II and III (FcgR2a, and FcgR3a) play a crucial role in the regulation of the immune response. The FcgR2a*519GG and FcgR3a*559CC genotypes have been associated with several autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, nephritis, and possibly to type I diabetes, and celiac disease. In a large multicenter, two-stage study of 6570 people, we tested whether the FcgR2a and FcgR3a genes were also involved in inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

We genotyped the FcgR2a*A519G and FcgR3a*A559C functional variants in 4205 IBD patients in six well-phenotyped Caucasian IBD cohorts and 2365 ethnically matched controls recruited from the Netherlands, Spain, and New Zealand.

RESULTS

In the initial Dutch study we found a significant association of FcgR2a genotypes with IBD (P-genotype = 0.02); while the FcgR2a*519GG was more common in controls (23%) than in IBD patients (18%; odds ratio [OR] = 0.75; 95% confidence interval [CI] 0.61-0.92; P = 0.004). This association was corroborated by a combined analysis across all the study populations (Mantel-Haenszel [MH] OR = 0.84; 0.74-0.95; P = 0.005) in the next stage. The Fcgr2a*GG genotype was associated with both UC (MH-OR = 0.84; 0.72-0.97; P = 0.01) and CD (MH-OR = 0.84; 0.73-0.97; P = 0.01), suggesting that this genotype confers a protective effect against IBD. There was no association of FcgR3a*A559C genotypes with IBD, CD, or UC in any of the three studied populations.

CONCLUSIONS

The FcgR2a*519G functional variant was associated with IBD and reduced susceptibility to UC and to CD in Caucasians. There was no association between FcgR3a*5A559C and IBD, CD or UC.

Olf1/EBF associated zinc finger protein interfered with antinuclear antibody production in patients with systemic lupus erythematosus

Introduction

The aim of the study was to determine whether Olf1/EBF associated zinc finger protein (OAZ), a transcription factor encoded by a positional systemic lupus erythematosus (SLE) candidate gene, plays a functional role in the pathogenesis in SLE.

Methods

Gene expression levels in peripheral blood cells (PBLs) measured using quantitative real-time polymerase chain reaction (qPCR) were assessed for association with disease activity and the presence of specific autoantibodies. Peripheral blood mononuclear cells (PBMCs) were incubated with specific siRNAs for three days, then cells were harvested for measuring mRNA levels using qPCR, and supernatants for levels of total immunoglobulin (Ig)G and IgM as well as secreted cytokines, chemokine and antinuclear antibodies (ANA) using ELISA. Indirect immunofluorescence was also applied for ANA detection.

Results

OAZ gene expressions in PBLs from 40 ANA-positive SLE patients were significantly increased than those from 30 normal controls (P < 0.0001) and 18 patients with rheumatoid arthritis (P < 0.01). In SLE patients, OAZ transcripts were positively correlated with SLE disease activity index (SLEDAI) score (r = 0.72, P < 0.0001) and higher in those positive for anti-dsDNA or anti-Sm antibodies (both P < 0.05). Co-culturing with OAZ siRNAs reduced mRNA levels of OAZ by 74.6 ± 6.4% as compared to those co-cultured with non-targeting siRNA and OAZ silencing resulted in reduced total IgG, ANA, interferon (IFN)-γ, interleukin (IL)-10, IL-12 and IL-21, but elevated CCL2 levels in culture supernatants (P < 0.05). The declined ANA levels correlated with inhibited OAZ expression (r = 0.88, P = 0.05), reduced IL-21 levels (r = 0.99, P < 0.01), and elevated chemokine (C-C motif) ligand 2 levels (r = -0.98, P < 0.01). Expressions of ID1-3 were significantly down-regulated by 68.7%, 70.2% and 67.7% respectively after OAZ silence, while ID3 was also highly expressed in SLE PBLs (P < 0.0001) and associated with disease activity (r = 0.76, P < 0.0001) as well as anti-dsDNA or anti-Sm antibodies (both P < 0.05).

Conclusions

Elevated expression of OAZ transcripts in SLE PBLs were strongly correlated with disease activity. Suppression of OAZ expression inhibited downstream ID levels, and secretion of ANA and IL-21, implicating a role of OAZ pathway in the pathogenesis of SLE.

Meta-analysis of 15 genome-wide linkage scans of smoking behavior

BACKGROUND

A genetic contribution to smoking behavior is well-established. To identify loci that increase the risk for smoking behavior, many genome-wide linkage scans have been performed with various smoking behavior assessments. Numerous putative susceptibility loci have been identified, but only a few of these were replicated in independent studies.

METHODS

We used genome search meta-analysis (GSMA) to identify risk loci by pooling all available independent genome scan results on smoking behavior. Additionally, to minimize locus heterogeneity, subgroup analyses of the smoking behavior assessed by the Fagerstrom Test for Nicotine Dependence (FTND) and maximum number of cigarettes smoked in a 24-hour period (MaxCigs24) were carried out. Samples of European ancestry were also analyzed separately.

RESULTS

A total number of 15 genome scan results were available for analysis, including 3404 families with 10,253 subjects. Overall, the primary GSMA across all smoking behavior identified a genome-wide suggestive linkage in chromosome 17q24.3-q25.3 (p(SR) = .001). A secondary analysis of FTND in European-ancestry samples (625 families with 1878 subjects) detected a genome-wide suggestive linkage in 5q33.1-5q35.2 (p(SR) = .0076). Subgroup analysis of MaxCigs24 (966 families with 3273 subjects) identified a genome-wide significant linkage in 20q13.12-q13.32 (p(SR) = .00041, p(OR) = .048), where a strongly supported nicotine dependence candidate gene, CHRNA4, is located.

CONCLUSIONS

The regions identified in the current study deserve close attention and will be helpful for candidate gene identification or target re-sequencing studies in the future.

The search for lupus biomarkers

Few biomarkers for systemic lupus erythematosus (SLE) have been validated and employed for making clinical decisions. The lack of reliable, specific biomarkers for SLE hampers the proper clinical management of patients with SLE and impedes the development of new lupus therapeutics. This void has led to renewed enthusiasm for identifying biomarkers that precisely and specifically reflect the pathophysiological and clinical changes of SLE. Several laboratory markers have shown early promise as biomarkers for lupus susceptibility, diagnosis and monitoring. These include polymorphisms and copy-number variations of complement C4 and Fcgamma receptor genes (disease susceptibility), cell-bound complement C4d (diagnosis and/or disease activity), CD27(high) plasma cells (disease activity), 'interferon signature' (disease activity) and anti-C1q and anti-NMDA (disease activity and organ involvement). Although these and other promising candidate biomarkers have been identified, they still need to be validated through rigorous, large-scale multicentre studies. This article briefly reviews the historical aspects of lupus biomarkers and summarises current efforts to advance the field.

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.

Meta-analysis of linkage studies for Alzheimer's disease--a web resource

Familial late-onset Alzheimer's disease (LOAD) shows high heritability. However, with the exception of ApoE, no well-replicated susceptibility genes have been identified to date. Several genome-wide linkage studies have nominated potential susceptibility loci but results are inconsistent, with individual scans showing few significant LOD scores. We have pooled linkage results from five independent genome scans and used the genome search meta-analysis (GSMA) method to analyse these data. The combined sample results in 2206 affected individuals and 785 families from Caucasian and Caribbean Hispanic ethnicities. The Caucasian samples included subjects from the US, the Netherlands and Sweden. Genome-wide suggestive evidence for linkage was observed on chromosomes 1p13.3-q31.1, 7pter-p21.1 and 8p22-p21.1 in the weighted GSMA analysis. The chromosome 8p region achieved the lowest summed rank p-value of 0.001. We also identified seven loci with nominally significant evidence for linkage to 3q12.3-q22.1, 6p21.1-q15, 7p14.1-q21.11, 17q24.3-qter and 19p13.3-qter. The GSMA finding suggests that these loci may harbour susceptibility genes for LOAD. We have also developed a web resource (http://alzres.iop.kcl.ac.uk/) to present additional GSMA analyses with different study selection criteria, facilitate the reanalysis of genome-wide linkage data and provide open access to the GSMA data.

Replication of the BANK1 genetic association with systemic lupus erythematosus in a European-derived population

Systemic lupus erythematosus (SLE) is an autoimmune disease with highly variable clinical presentation. Patients suffer from immunological abnormalities that target T-cell, B-cell and accessory cell functions. B cells are hyperactive in SLE patients. An adapter protein expressed in B cells called BANK1 (B-cell scaffold protein with ankyrin repeats) was reported in a previous study to be associated with SLE in a European population. The objective of this study was to assess the BANK1 genotype-phenotype association in an independent replication sample. We genotyped 38 single nucleotide polymorphisms (SNPs) in BANK1 on 1892 European-derived SLE patients and 2652 European-derived controls. The strongest associations with SLE and BANK1 were at rs17266594 (corrected P-value=1.97 x 10(-5), odds ratio (OR)=1.22, 95% CI 1.12-1.34) and rs10516487 (corrected P-value=2.59 x 10(-5), OR=1.22, 95% CI 1.11-1.34). Our findings suggest that the association is explained by these two SNPs, confirming previous reports that these polymorphisms contribute to the risk of developing lupus. Analysis of patient subsets enriched for hematological, immunological and renal ACR criteria or the levels of autoantibodies, such as anti-RNP A and anti-SmRNP, uncovers additional BANK1 associations. Our results suggest that BANK1 polymorphisms alter immune system development and function to increase the risk for developing lupus.

Meta-analysis of genome-wide linkage studies across autoimmune diseases

Autoimmune diseases are chronic disorders initiated by a loss of immunologic tolerance to self-antigens. They cluster within families, and patients may be diagnosed with more than one disease, suggesting pleiotropic genes are involved in the aetiology of different diseases. To identify potential loci, which confer susceptibility to autoimmunity independent of disease phenotype, we pooled results from genome-wide linkage studies, using the genome scan meta-analysis method (GSMA). The meta-analysis included 42 independent studies for 11 autoimmune diseases, using 7350 families with 18 291 affected individuals. In addition to the HLA region, which showed highly significant genome-wide evidence for linkage, we obtained suggestive evidence for linkage on chromosome 16, with peak evidence at 10.0-19.8 Mb. This region may harbour a pleiotropic gene (or genes) conferring risk for several diseases, although no such gene has been identified through association studies. We did not identify evidence for linkage at several genes known to confer increased risk to different autoimmune diseases (PTPN22, CTLA4), even in subgroups of diseases consistently found to be associated with these genes. The relative risks conferred by variants in these genes are modest (<1.5 in most cases), and even a large study like this meta-analysis lacks power to detect linkage. This study illustrates the concept that linkage and association studies have power to identify very different types of disease-predisposing variants.

Identification of two independent risk factors for lupus within the MHC in United Kingdom families

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.

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.

Defining the role of the MHC in autoimmunity: a review and pooled analysis

The major histocompatibility complex (MHC) is one of the most extensively studied regions in the human genome because of the association of variants at this locus with autoimmune, infectious, and inflammatory diseases. However, identification of causal variants within the MHC for the majority of these diseases has remained difficult due to the great variability and extensive linkage disequilibrium (LD) that exists among alleles throughout this locus, coupled with inadequate study design whereby only a limited subset of about 20 from a total of approximately 250 genes have been studied in small cohorts of predominantly European origin. We have performed a review and pooled analysis of the past 30 years of research on the role of the MHC in six genetically complex disease traits - multiple sclerosis (MS), type 1 diabetes (T1D), systemic lupus erythematosus (SLE), ulcerative colitis (UC), Crohn's disease (CD), and rheumatoid arthritis (RA) - in order to consolidate and evaluate the current literature regarding MHC genetics in these common autoimmune and inflammatory diseases. We corroborate established MHC disease associations and identify predisposing variants that previously have not been appreciated. Furthermore, we find a number of interesting commonalities and differences across diseases that implicate both general and disease-specific pathogenetic mechanisms in autoimmunity.

HLA-G genotype and HLA-G expression in systemic lupus erythematosus: HLA-G as a putative susceptibility gene in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease mainly mediated by the deposit of immune complexes and defects in T lymphocytes and antigen-presenting cells along with a high production of T-helper 2 cytokines. A tolerance-inducible function of nonclassical class Ib human leukocyte antigen (HLA)-G molecule in innate and adaptive cellular responses has been reported, suggesting a role in inflammatory diseases. A 14 bp sequence insertion/deletion polymorphism (rs16375) in the 3'-untranslated region of the HLA-G gene has been associated to the stability of HLA-G messenger RNA. The insertion of the 14 bp sequence seems to be associated with lower levels of soluble HLA-G (sHLA-G). The aim of this study was to evaluate the possible association of the presence of the 14 bp sequence (+14 bp) with SLE. We have HLA-G genotyped 200 SLE patients and 451 healthy control subjects (HS; Italian) and analyzed the plasma levels of sHLA-G and interleukin-10 (IL-10) in a subset of SLE patients and healthy subjects (Italian and Danish). A significant increase of the +14 bp HLA-G allele was detected in the Italian SLE patients compared with HS [P = 0.003, OR 1.44 (95% CI 1.13-1.82)]. A significant increased frequency of HLA-G +14/+14 bp and a decreased frequency of HLA-G -14/-14 bp were observed in SLE patients. There median concentration of sHLA-G was significantly lower in the plasma of SLE patients compared with that in the plasma of healthy controls (P < 0.0001). Furthermore, the results confirmed higher concentrations of IL-10-positive plasma in SLE patients. These results support a potential role for HLA-G in the susceptibility of 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.

Primer: strategies for identifying genes involved in renal disease

The globally increasing number of patients with end-stage renal disease urges the identification of molecular pathways involved in renal pathophysiology, to serve as targets for intervention. Moreover, the identification of genetic risk factors or protective genes can aid tailored therapy. Tools that can be used to identify genes involved in renal disease include gene expression arrays, linkage analysis and association studies. Arrays are a powerful and widely used approach to the analysis of gene transcription and protein expression, whereas linkage analysis and association studies link disease susceptibility to particular genetic regions. Animal models are available to pinpoint the disease-associated genes. Candidate genes so far identified in renal disease include those encoding the podocyte proteins nephrin and podocin, the transcription factor WT1, the calcium channel TRPC6 and the enzyme phospholipase C-epsilon-1 (in congenital nephrotic syndrome and focal segmental glomerulosclerosis), and carnosinase (in diabetic nephropathy). In addition, linkage studies have identified chromosomal regions implicated in systemic lupus erythematosus, diabetic nephropathy and familial IgA nephropathy. Future studies will elucidate the emerging role of epigenetic regulation of gene expression in renal disease.

Genome-wide association scan in women with systemic lupus erythematosus identifies susceptibility variants in ITGAM, PXK, KIAA1542 and other loci

Systemic lupus erythematosus (SLE) is a common systemic autoimmune disease with complex etiology but strong clustering in families (lambda(S) = approximately 30). We performed a genome-wide association scan using 317,501 SNPs in 720 women of European ancestry with SLE and in 2,337 controls, and we genotyped consistently associated SNPs in two additional independent sample sets totaling 1,846 affected women and 1,825 controls. Aside from the expected strong association between SLE and the HLA region on chromosome 6p21 and the previously confirmed non-HLA locus IRF5 on chromosome 7q32, we found evidence of association with replication (1.1 x 10(-7) < P(overall) < 1.6 x 10(-23); odds ratio = 0.82-1.62) in four regions: 16p11.2 (ITGAM), 11p15.5 (KIAA1542), 3p14.3 (PXK) and 1q25.1 (rs10798269). We also found evidence for association (P < 1 x 10(-5)) at FCGR2A, PTPN22 and STAT4, regions previously associated with SLE and other autoimmune diseases, as well as at > or =9 other loci (P < 2 x 10(-7)). Our results show that numerous genes, some with known immune-related functions, predispose to SLE.

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.

Meta-analysis of HLA-DRB1 and HLA-DQB1 polymorphisms in Latin American patients with systemic lupus erythematosus

OBJECTIVE

To estimate the common effect size of HLA-DRB1 and -DQB1 alleles on systemic lupus erythematosus (SLE) susceptibility across Latin America populations through a meta-analysis.

METHODS

Case-control studies on HLA class II association with SLE in Latin America were searched up to August 2007. The effect summary odds ratios (ORs) and 95% confidence intervals (CIs) were obtained by means of the random effect model.

RESULTS

Eleven studies were selected, which included 747 cases and 1180 controls. Associations with SLE susceptibility were found for HLA-DR2 (OR: 1.75; 95% CI: 1.40-2.19) and -DR3 (OR: 2.02; 95% CI: 1.44-2.83) groups. HLA-DRB1*0301 allele disclosed the strongest association (OR: 2.14; 95% CI: 1.28-3.56). HLA-DR3-DQ2 haplotype was a risk factor (OR: 2.92; 95% CI: 1.66-5.14). A protective effect was found for the HLA-DR5 group (OR: 0.43; 95% CI: 0.27-0.67), mainly due to a negative association between HLA-DRB1*1101 allele and disease (OR: 0.21; 95% CI: 0.06-0.72). Functional analysis of susceptibility and protective alleles revealed physicochemical differences of critical amino acids shaping the peptide-binding groove at DRbeta chain allowing us to infer an approach to understand the role of HLA in SLE. No significant association was established for HLA-DQB1 alleles.

CONCLUSIONS

HLA-DRB1 gene is a mayor factor for development of SLE in Latin Americans.

Polymorphism at the TNF superfamily gene TNFSF4 confers susceptibility to systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystem complex autoimmune disease of uncertain etiology (OMIM 152700). Over recent years a genetic component to SLE susceptibility has been established. Recent successes with association studies in SLE have identified genes including IRF5 (refs. 4,5) and FCGR3B. Two tumor necrosis factor (TNF) superfamily members located within intervals showing genetic linkage with SLE are TNFSF4 (also known as OX40L; 1q25), which is expressed on activated antigen-presenting cells (APCs) and vascular endothelial cells, and also its unique receptor, TNFRSF4 (also known as OX40; 1p36), which is primarily expressed on activated CD4+ T cells. TNFSF4 produces a potent co-stimulatory signal for activated CD4+ T cells after engagement of TNFRSF4 (ref. 11). Using both a family-based and a case-control study design, we show that the upstream region of TNFSF4 contains a single risk haplotype for SLE, which is correlated with increased expression of both cell-surface TNFSF4 and the TNFSF4 transcript. We hypothesize that increased expression of TNFSF4 predisposes to SLE either by quantitatively augmenting T cell-APC interaction or by influencing the functional consequences of T cell activation via TNFRSF4.

The MHC2TA-168A/G and +1614G/C polymorphisms and risk for multiple sclerosis or chronic inflammatory arthropathies

The -168A-G polymorphism has been shown to influence transcription of the MHC2TA gene and has been implicated in several inflammatory/autoimmune disorders. Attempts to reproduce these findings have been inconclusive. We investigated the role of this promoter single nucleotide polymorphism (SNP) in 440 multiple sclerosis (MS), 293 rheumatoid arthritis (RA), 74 juvenile idiopathic arthritis (JIA) patients and 316 healthy controls from Northern Ireland. We also genotyped a non-synonymous SNP in exon 11, +1614G/C. There was no significant difference in the -168G allele frequencies and carriage rates in the separate RA, JIA, or MS collections compared with the control group [odds ratio (OR) = 1.1, 95% confidence intervals (CI) = 0.86-1.44; OR = 1.1, 95% CI = 0.75-1.68; OR = 1.1, 95% CI = 0.84-1.35, respectively]. Assessment of the common phenotype (chronic inflammatory disease; n = 807 vs 316 controls) was negative as well. Carriage of +1614C was protective against JIA (OR = 0.6, 95% CI = 0.3-1.0) and showed a similar trend in RA and MS (OR = 0.7, 95% CI = 0.5-1.0; OR = 0.8, 95% CI = 0.6-1.0, respectively). The common phenotype (chronic inflammatory disease) was also significant (OR = 0.7, 95% CI = 0.6-1.0).

Gene copy-number variation and associated polymorphisms of complement component C4 in human systemic lupus erythematosus (SLE): low copy number is a risk factor for and high copy number is a protective factor against SLE susceptibility in European Americans

Interindividual gene copy-number variation (CNV) of complement component C4 and its associated polymorphisms in gene size (long and short) and protein isotypes (C4A and C4B) probably lead to different susceptibilities to autoimmune disease. We investigated the C4 gene CNV in 1,241 European Americans, including patients with systemic lupus erythematosus (SLE), their first-degree relatives, and unrelated healthy subjects, by definitive genotyping and phenotyping techniques. The gene copy number (GCN) varied from 2 to 6 for total C4, from 0 to 5 for C4A, and from 0 to 4 for C4B. Four copies of total C4, two copies of C4A, and two copies of C4B were the most common GCN counts, but each constituted only between one-half and three-quarters of the study populations. Long C4 genes were strongly correlated with C4A (R=0.695; P<.0001). Short C4 genes were correlated with C4B (R=0.437; P<.0001). In comparison with healthy subjects, patients with SLE clearly had the GCN of total C4 and C4A shifting to the lower side. The risk of SLE disease susceptibility significantly increased among subjects with only two copies of total C4 (patients 9.3%; unrelated controls 1.5%; odds ratio [OR] = 6.514; P=.00002) but decreased in those with > or =5 copies of C4 (patients 5.79%; controls 12%; OR=0.466; P=.016). Both zero copies (OR=5.267; P=.001) and one copy (OR=1.613; P=.022) of C4A were risk factors for SLE, whereas > or =3 copies of C4A appeared to be protective (OR=0.574; P=.012). Family-based association tests suggested that a specific haplotype with a single short C4B in tight linkage disequilibrium with the -308A allele of TNFA was more likely to be transmitted to patients with SLE. This work demonstrates how gene CNV and its related polymorphisms are associated with the susceptibility to a human complex disease.

Meta-analysis of genome-wide linkage studies for multiple sclerosis, using an extended GSMA method

Many genome-wide linkage studies in multiple sclerosis (MS) have been performed, but results are disappointing, with linkage confirmed only in the HLA region. We combined results from all available, non-overlapping genome-wide linkage studies in MS using the Genome Search Meta-Analysis method (GSMA). The GSMA is a rank-based analysis, which assesses the strongest evidence for linkage within bins of traditionally 30 cM width on the autosomes and X chromosome. Genome-wide evidence for linkage was confirmed on chromosome 6p (HLA region; P=0.00004). Suggestive evidence for linkage was found on chromosomes 10q (P=0.0077), 18p (P=0.0054) and 20p (P=0.0079). To explore how these results could be affected by bin definition, we analysed the data using different bin widths (20 and 40 cM) and using a shifted 30 cM bin by moving bin boundaries by 15 cM. Consistently significant results were obtained for the 6p region. The regions on 10q and 18p provided suggestive evidence for linkage in some analyses, and, interestingly, a region on 6q, that showed only nominal significance in the original analysis, yielded increased, suggestive significance in two of the additional analyses. These regions may provide targets to focus candidate gene studies or to prioritise results from genome-wide association studies.

Developments in lupus 2006

Published reports in 2006 on systemic lupus erythematosus are reviewed with regard to preclinical and clinical studies on disturbances of the immune system including co-stimulation, cytokines and recent insights into new therapeutic approaches. Increasing knowledge of components of the innate immune system, such as certain receptors (Toll-like receptors, Fc receptors and complement receptors) and cytokines as well as immune cells (dendritic cells, plasmacytoid cells and neutrophils) supports their immunopathogenic relevance and enhance our understanding of the pathogenic complexity of lupus. Although it remains to be shown which of those could be targets for therapy or biomarkers, lymphocyte-directed therapy is currently under promising clinical investigation.