Rare variation at the TNFAIP3 locus and susceptibility to rheumatoid arthritis

Low-frequency and rare genetic variants associated with rheumatoid arthritis risk

Rheumatoid arthritis (RA) has an estimated heritability of nearly 50%, which is particularly high in seropositive RA. HLA alleles account for a large proportion of this heritability, in addition to many common single-nucleotide polymorphisms with smaller individual effects. Low-frequency and rare variants, such as those captured by next-generation sequencing, can also have a large role in heritability in some individuals. Rare variant discovery has informed the development of drugs such as inhibitors of PCSK9 and Janus kinases. Some 34 low-frequency and rare variants are currently associated with RA risk. One variant (19:10352442G>C in TYK2) was identified in five separate studies, and might therefore represent a promising therapeutic target. Following a set of best practices in future studies, including studying diverse populations, using large sample sizes, validating RA and serostatus, replicating findings, adjusting for other variants and performing functional assessment, could help to ensure the relevance of identified variants. Exciting opportunities are now on the horizon for genetics in RA, including larger datasets and consortia, whole-genome sequencing and direct applications of findings in the management, and especially treatment, of RA.

Comprehensive analysis of hub biomarkers associated with immune and oxidative stress in Hashimoto's thyroiditis

Hashimoto's thyroiditis (HT) is a type of autoimmune disorder with a complex interplay between immune disorder and oxidative stress (OS). This research aimed to discover biomarkers and potential treatment targets associated with immune and OS dysregulation in HT through integrated bioinformatics analysis and clinical validations. Differential gene expression analysis of GSE138198 dataset from the GEO database identified 1490 differentially expressed genes (DEGs) in HT, including 883 upregulated and 607 downregulated genes. Weighted gene co-expression network analysis explored module genes associated with HT. Overlapping the differentially expressed module genes with immune-related and OS-related genes identified eight differentially expressed module genes associated with immune and OS (DEIOGs) in HT. Protein-protein interaction network analysis identified five hub genes (TNFAIP3, FOS, PTK2B, STAT1, and MMP9). We confirmed four hub genes (TNFAIP3, PTK2B, STAT1 and MMP9) in GSE29315 dataset and clinical thyroid samples, which showed high diagnostic accuracy (AUC >0.7) for HT. The expression of these four genes was positively correlated with serum thyroid peroxidase antibody, thyroglobulin antibody levels, and inflammatory infiltration scores in clinical thyroid samples. Immune profiling revealed distinct profiles in HT, such as B cells memory, monocytes and macrophages. Additionally, all hub genes were inversely associated with monocytes. Further, miRNA-mRNA network analysis was conducted, and a regulatory network comprising four hub genes, 238 miRNAs and 32 TFs was established. These findings suggest that immune cells play a crucial role in the development of HT, and the hub genes TNFAIP3, PTK2B, STAT1, and MMP9 may be key players in HT through immune- and OS-related signaling pathways. Our results may provide valuable insights into the pathogenesis and therapeutic monitoring of HT.

Overexpression of the ubiquitin-editing enzyme A20 in the brain lesions of Multiple Sclerosis patients: moving from systemic to central nervous system inflammation

Multiple Sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS) in which inflammation plays a key pathological role. Recent evidences showed that systemic inflammation induces increasing cell infiltration within meninges and perivascular spaces in the brain parenchyma, triggering resident microglial and astrocytic activation. The anti-inflammatory enzyme A20, also named TNF associated protein 3 (TNFAIP3), is considered a central gatekeeper in inflammation and peripheral immune system regulation through the inhibition of NF-kB. The TNFAIP3 locus is genetically associated to MS and its transcripts is downregulated in blood cells in treatment-naïve MS patients. Recently, several evidences in mouse models have led to hypothesize a function of A20 also in the CNS. Thus, here we aimed to unveil a possible contribution of A20 to the CNS human MS pathology. By immunohistochemistry/immunofluorescence and biomolecular techniques on post-mortem brain tissue blocks obtained from control cases (CC) and progressive MS cases, we demonstrated that A20 is present in CC brain tissues in both white matter (WM) regions, mainly in few parenchymal astrocytes, and in grey matter (GM) areas, in some neuronal populations. Conversely, in MS brain tissues, we observed increased expression of A20 by perivascular infiltrating macrophages, resident-activated astrocytes, and microglia in all the active and chronic active WM lesions. A20 was highly expressed also in the majority of active cortical lesions compared to the neighboring areas of normal-appearing grey matter (NAGM) and control GM, particularly by activated astrocytes. We demonstrated increased A20 expression in the active MS plaques, particularly in macrophages and resident astrocytes, suggesting a key role of this molecule in chronic inflammation.

Latin American Genes: The Great Forgotten in Rheumatoid Arthritis

The successful implementation of personalized medicine will rely on the integration of information obtained at the level of populations with the specific biological, genetic, and clinical characteristics of an individual. However, because genome-wide association studies tend to focus on populations of European descent, there is a wide gap to bridge between Caucasian and non-Caucasian populations before personalized medicine can be fully implemented, and rheumatoid arthritis (RA) is not an exception. In this review, we discuss advances in our understanding of genetic determinants of RA risk among global populations, with a focus on the Latin American population. Geographically restricted genetic diversity may have important implications for health and disease that will remain unknown until genetic association studies have been extended to include Latin American and other currently under-represented ancestries. The next few years will witness many breakthroughs in personalized medicine, including applications for common diseases and risk stratification instruments for targeted prevention/intervention strategies. Not all of these applications may be extrapolated from the Caucasian experience to Latin American or other under-represented populations.

TNFAIP3 Deficiency Affects Monocytes, Monocytes-Derived Cells and Microglia in Mice

The intracellular-ubiquitin-ending-enzyme tumor necrosis factor alpha-induced protein 3 (TNFAIP3) is a potent inhibitor of the pro-inflammatory nuclear factor kappa-light-chain-enhancer of activated B cell (NF-kB) pathway. Single nucleotide polymorphisms in TNFAIP3 locus have been associated to autoimmune inflammatory disorders, including Multiple Sclerosis (MS). Previously, we reported a TNFAIP3 down-regulated gene expression level in blood and specifically in monocytes obtained from treatment-naïve MS patients compared to healthy controls (HC). Myeloid cells exert a key role in the pathogenesis of MS. Here we evaluated the effect of specific TNFAIP3 deficiency in myeloid cells including monocytes, monocyte-derived cells (M-MDC) and microglia analyzing lymphoid organs and microglia of mice. TNFAIP3 deletion is induced using conditional knock-out mice for myeloid lineage. Flow-cytometry and histological procedures were applied to assess the immune cell populations of spleen, lymph nodes and bone marrow and microglial cell density in the central nervous system (CNS), respectively. We found that TNFAIP3 deletion in myeloid cells induces a reduction in body weight, a decrease in the number of M-MDC and of common monocyte and granulocyte precursor cells (CMGPs). We also reported that the lack of TNFAIP3 in myeloid cells induces an increase in microglial cell density. The results suggest that TNFAIP3 in myeloid cells critically controls the development of M-MDC in lymphoid organ and of microglia in the CNS.

Deubiquitinating enzymes (DUBs): DoUBle-edged swords in CNS autoimmunity

Multiple sclerosis (MS) is the most common autoimmune disease of the CNS. The etiology of MS is still unclear but it is widely recognized that both genetic and environmental factors contribute to its pathogenesis. Immune signaling and responses are critically regulated by ubiquitination, a posttranslational modification that is promoted by ubiquitinating enzymes and inhibited by deubiquitinating enzymes (DUBs). Genome-wide association studies (GWASs) identified that polymorphisms in or in the vicinity of two human DUB genes TNFAIP3 and USP18 were associated with MS susceptibility. Studies with experimental autoimmune encephalomyelitis (EAE), an animal model of MS, have provided biological rationale for the correlation between these DUBs and MS. Additional studies have shown that other DUBs are also involved in EAE by controlling distinct cell populations. Therefore, DUBs are emerging as crucial regulators of MS/EAE and might become potential therapeutic targets for the clinical treatment of MS.

TNFSF4 Gene Variations Are Related to Early-Onset Autoimmune Thyroid Diseases and Hypothyroidism of Hashimoto's Thyroiditis

The aim of the current study was to examine whether the polymorphism loci of the tumor necrosis factor superfamily member 4 (TNFSF4) gene increase the risk of susceptibility to autoimmune thyroid diseases (AITDs) in the Han Chinese population, and a case-control study was performed in a set of 1,048 AITDs patients and 909 normal healthy controls in the study. A total of four tagging single nucleotide polymorphisms (SNPs) in the TNFSF4 region, including rs7514229, rs1234313, rs16845607 and rs3850641, were genotyped using the method of ligase detection reaction. An association between GG genotype of rs3850641 in TNFSF4 gene and AITDs was found (p = 0.046). Additionally, the clinical sub-phenotype analysis revealed a significant association between GG genotype in rs7514229 and AITDs patients who were ≤18 years of age. Furthermore, rs3850641 variant allele G was in strong association with hypothyroidism in Hashimoto’s thyroiditis (HT) (p = 0.018). The polymorphisms of the TNFSF4 gene may contribute to the susceptibility to AITDs pathogenesis.

The role of the ubiquitin-editing enzyme A20 in diseases of the central nervous system and other pathological processes

In recent years, the ubiquitin-editing enzyme A20 has been shown to control a large set of molecular pathways involved in the regulation of protective as well as self-directed immune responses. Here, we assess the current and putative roles of A20 in inflammatory, vascular and degenerative diseases of the central nervous system and explore future directions of research.

Genetic, genomic and epigenetic studies as tools for elucidating disease pathogenesis in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is characterized by lymphoid infiltration of lacrimal and salivary glands leading to xerophthalmia and xerostomia. pSS is a complex disease involving both genetic and environmental risk factors. Technological advances over the past 10 years have revolutionized genetics and genomics research enabling high-throughput characterization and analysis of DNA and RNA in patient samples on a genome-wide scale. Further, application of high-throughput methods for characterization of epigenetic variation, such as DNA methylation status, is increasingly being applied to AID populations and will likely further define additional risk factors for disease risk and outcome. Main results obtain in pSS through these various approaches are reviewed here.

TNFAIP3 gene polymorphisms associated with differential susceptibility to rheumatoid arthritis and systemic lupus erythematosus in the Korean population

OBJECTIVE

We investigated the relationship between polymorphisms in the TNF-a-induced protein 3 (TNFAIP3) gene and genetic susceptibility to SLE and RA in the Korean population.

METHODS

The present case control study included 422 patients with RA, 133 patients with SLE and 422 healthy controls. Genotyping for TNFAIP3 gene polymorphisms rs5029941 (C>T), rs2230926 (T>G), rs5029930 (C>A), rs5029937 (G>T) and rs5029939 (G>C) in TNFAIP3 gene polymorphisms was performed. The status of RA-related autoantibodies, including RF and anti-CCP, in RA and the presence of arthritis and nephritis in SLE were assessed.

RESULTS

Significantly different frequencies of minor alleles in two TNFAIP3 polymorphisms were found in patients with SLE compared with healthy controls [odds ratio (OR) 2.13, 95% CI 1.25, 3.65, P= 0.02 for rs5029937; OR 2.17, 95% CI 1.27, 3.72, P= 0.01 for rs5029939). Moreover, patients with SLE showed different frequencies of haplotypes compared with healthy controls (P<0.001). However, no association was found between RA susceptibility and TNFAIP3 polymorphisms (P= 0.28). Interactions between RA-related autoantibody status and TNFAIP3 polymorphisms were not associated with RA susceptibility. Interestingly, arthritis in patients with SLE was marginally associated with TNFAIP3 polymorphisms (P= 0.04).

CONCLUSION

The results suggest that TNFAIP3 gene polymorphisms are associated with differential susceptibility to SLE and RA in the Korean population. The relationship between TNFAIP3 gene polymorphisms and RA susceptibility may be dependent on ethnic background.

Single nucleotide polymorphisms in TNFAIP3 were associated with the risks of rheumatoid arthritis in northern Chinese Han population

BACKGROUND

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic destructive inflammation in synovial joints. It is well known that genetic and environmental risk factors and their interaction contribute to RA pathogenesis. This study aimed to investigate the association between the critical polymorphisms in the tumor necrosis factor α (TNFα)-induced protein 3(TNFAIP3) gene and the risk of RA in a large northern Chinese Han population.

METHODS

A case-control study of 1280 RA patients and 1280 matched healthy controls was conducted.

RESULTS

This study showed that carriers of the rs2230926 TG genotype or rs10499194 CT genotype had an increased risk for RA compared with those carrying the wild genotype (rs2230926: OR = 1.48, 95% CI = 1.17-1.86, p = 0.001; rs10499194: OR = 2.00, 95% CI = 1.46-2.74, p < 0.001). The combined rs2230926TG/GG or rs10499194 CT/TT were associated with an increased risk of RA (ORs were 1.50 and 2.01, 95% CIs were 1.19-1.88 and 1.47-2.74, respectively, both p < 0.001). There was not significant association between rs13207033 polymorphism and RA risk. Subset analysis stratified to gender showed that the increased risks were significant among the genotypes TG, TG/GG of rs2230926 and CT, CT/TT of rs10499194 and the corresponding ORs were 1.42 (95%  CI = 1.10-1.83, p = 0.006), 1.44(95% CI = 1.12-1.85, p = 0.004), 1.52(95% CI = 1.05-2.20, p = 0.026) and 1.52(95% CI = 1.06-2.19, p = 0.023) in the female population. Stratified analyses by age found that rs2230926(TG, TG/GG) and rs10499194(CT, CT/TT) polymorphisms were associated with RA risks in population ≤53 years old and among >53 years old only rs10499194(CT, TT, CT/TT) polymorphism had significant results. The interaction analysis suggested that individuals with both risk genotypes of the two SNPs have a higher elevated risk of RA than those with only one of them (ORs were 3.44 compared to 1.74 and 1.35). The haplotype results showed that individuals with the rs2230926G-rs13207033G-rs10499194C haplotype were associated with increased risks of RA (OR = 1.37, 95% CI = 1.08-1.74, p = 0.010).

CONCLUSIONS

Rs10499194 and rs2230926 polymorphisms in the TNFAIP3 gene region may be susceptibility factors for rheumatoid arthritis in the northern Chinese Han population.

Rare variants and autoimmune disease

The study of rare variants in monogenic forms of autoimmune disease has offered insight into the aetiology of more complex pathologies. Research in complex autoimmune disease initially focused on sequencing candidate genes, with some early successes, notably in uncovering low-frequency variation associated with Type 1 diabetes mellitus. However, other early examples have proved difficult to replicate, and a recent study across six autoimmune diseases, re-sequencing 25 autoimmune disease-associated genes in large sample sizes, failed to find any associated rare variants. The study of rare and low-frequency variation in autoimmune diseases has been made accessible by the inclusion of such variants on custom genotyping arrays (e.g. Immunochip and Exome arrays). Whole-exome sequencing approaches are now also being utilised to uncover the contribution of rare coding variants to disease susceptibility, severity and treatment response. Other sequencing strategies are starting to uncover the role of regulatory rare variation.

Polymorphisms of the TNFAIP3 region and Graves' disease

Autoimmune thyroid disease (AITD) is a multifactorial organ-specific autoimmune disorder, and both genetic susceptibility and environmental factors are involved in its etiology. TNFAIP3 encodes the ubiquitin-modifying enzyme (A20), a key regulator of inflammatory signaling pathways. The aim of the present study was to evaluate the association between TNFAIP3 gene polymorphisms and AITD in Chinese Han population. Three single nucleotide polymorphisms (SNPs) in TNFAIP3 gene locus (rs598493, rs610604 and rs661561) were detected in a set of 667 patients with AITD and 301 controls in Han Chinese population using the Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometer (MALDI-TOF-MS) Platform. Compared with those of the controls, the frequencies of GG genotype of rs598493, the AA genotype of rs610604, the allele G and GG genotype of rs661561 were significantly increased in Graves' disease (GD) patients. However, the frequencies of AG genotype of rs598493 and AC genotype of rs610604 were significantly decreased in GD patients. The ATC haplotype (rs598493, rs661561 and rs610604) was associated with a decreased risk of GD. No significant differences in the three SNPs were observed between HT patients and controls. Our study shows a clear association between the polymorphisms of TNFAIP3 gene and GD, not HT, suggesting that TNFAIP3 gene is likely to be a genetic susceptibility factor to GD.

The deubiquitinase A20 in immunopathology of autoimmune diseases

Deubiquitination-mediated regulation is important for homeostatic NF-κB activation. Aberrant NF-κB activation associated with various inflammatory and autoimmune disorders is linked with defects in the deubiquitinase A20. A20 is an important anti-inflammatory molecule that is induced by multiple signals and has numerous targets. Polymorphisms within the A20 locus or its altered expression are thought to contribute in development of autoimmune disorders. Further various studies in mice models underscore the biological importance of A20 in prevention of inflammatory conditions. Dysregulated A20 is also been suggested as a link between prolonged inflammation and cancer by preliminary reports. This review summarizes the existing understanding and focuses on the new developments in the field of A20 biology. These developments highlight the importance of A20 in pathophysiology of autoimmune disorders and its scope as therapeutics and a biomarker.

Rare variants detection with kernel machine learning based on likelihood ratio test

This paper mainly utilizes likelihood-based tests to detect rare variants associated with a continuous phenotype under the framework of kernel machine learning. Both the likelihood ratio test (LRT) and the restricted likelihood ratio test (ReLRT) are investigated. The relationship between the kernel machine learning and the mixed effects model is discussed. By using the eigenvalue representation of LRT and ReLRT, their exact finite sample distributions are obtained in a simulation manner. Numerical studies are performed to evaluate the performance of the proposed approaches under the contexts of standard mixed effects model and kernel machine learning. The results have shown that the LRT and ReLRT can control the type I error correctly at the given α level. The LRT and ReLRT consistently outperform the SKAT, regardless of the sample size and the proportion of the negative causal rare variants, and suffer from fewer power reductions compared to the SKAT when both positive and negative effects of rare variants are present. The LRT and ReLRT performed under the context of kernel machine learning have slightly higher powers than those performed under the context of standard mixed effects model. We use the Genetic Analysis Workshop 17 exome sequencing SNP data as an illustrative example. Some interesting results are observed from the analysis. Finally, we give the discussion.

A method to incorporate prior information into score test for genetic association studies

Background

The interest of the scientific community in investigating the impact of rare variants on complex traits has stimulated the development of novel statistical methodologies for association studies. The fact that many of the recently proposed methods for association studies suffer from low power to identify a genetic association motivates the incorporation of prior knowledge into statistical tests.

Results

In this article we propose a methodology to incorporate prior information into the region-based score test. Within our framework prior information is used to partition variants within a region into several groups, following which asymptotically independent group statistics are constructed and then combined into a global test statistic. Under the null hypothesis the distribution of our test statistic has lower degrees of freedom compared with those of the region-based score statistic. Theoretical power comparison, population genetics simulations and results from analysis of the GAW17 sequencing data set suggest that under some scenarios our method may perform as well as or outperform the score test and other competing methods.

Conclusions

An approach which uses prior information to improve the power of the region-based score test is proposed. Theoretical power comparison, population genetics simulations and the results of GAW17 data analysis showed that for some scenarios power of our method is on the level with or higher than those of the score test and other methods.

Genetics in rheumatoid arthritis beyond HLA genes: what meta-analyses have shown?

OBJECTIVE

Rheumatoid arthritis (RA) is a complex disorder with many genetic and environmental factors to account for disease susceptibility. Individual genetic association studies usually suffer from small sample size leading to biased results of polymorphisms association with RA liability. Therefore, meta-analyses seem to resolve this limitation, up to a point, increasing the power of statistical analyses. In this review, we summarize the current knowledge of non-HLA genetic factors contributing to RA predisposition based on meta-analyses.

METHODS

Using the key words: rheumatoid arthritis, meta-analysis, and polymorphism, we searched the PubMed database for the associated articles. Up to the middle of November 2012, seventy-nine articles fulfilled the criteria and highlighted the current findings on the genetic factors contributing to RA susceptibility.

RESULTS

The association with RA was confirmed for 32 gene polymorphisms, being population specific in some cases. However, meta-analyses did not confirm an association in case of 16 gene variants, previously studied in individual studies for their association with RA.

CONCLUSIONS

The use of bioinformatics tools and functional studies of the summarized implicated genes in RA pathogenesis could shed light on the molecular pathways related to the disorder, helping to the development of new drug targets for a better treatment of RA.

TNFAIP3 gene polymorphisms in a Chinese Han population with Vogt-Koyanagi-Harada syndrome

Background

This study was performed to evaluate the potential association of TNFAIP3 polymorphisms with Vogt–Koyanagi–Harada (VKH) disease in a Chinese Han population.

Methodology/Principal Findings

Five single-nucleotide polymorphisms (SNPs), rs10499194, rs610604, rs7753873, rs5029928 and rs9494885 of TNFAIP3 were genotyped in 834 VKH disease patients and 1415 healthy controls using a PCR-restriction fragment length polymorphism assay. An increased frequency of the C allele and CT genotype for rs9494885 were found in VKH patients in the Guangzhou and Chongqing cohorts (pc = 0.015, OR = 1.6, pc = 0.036, OR = 1.7; pc = 2.36×10−4, OR = 1.5, pc = 0.012, OR = 1.5, respectively). Meanwhile, a decreased frequency of the TT genotype for rs9494885 was observed in VKH patients in the Guangzhou and Chongqing cohorts (pc = 0.026, OR = 0.6, pc = 0.0074, OR = 0.7, respectively). The combined analysis showed that a significantly increased prevalence of the rs9494885 TC genotype and C allele were found in VKH disease patients compared with controls (pc = 2.26×10−5, OR = 1.7; pc = 1.09× 10−5, OR = 1.6, respectively). The frequency of the TT genotype of rs9494885 was markedly lower in VKH disease patients as compared with that in controls (pc = 1.12×10−5, OR = 0.6; p_c = 1.09×10⁻⁵, OR = 0.6, respectively). No association was found between rs10499194, rs610604, rs7753873 and rs5029928 polymorphisms and VKH disease. To our knowledge this is the first report describing the association of a TNFAIP3 gene polymorphism with VKH disease in a Chinese Han population.

Conclusions/Significance

The results suggest that the rs9494885 TC genotype and C allele may be predisposing factors to VKH disease, whereas the rs9494885 TT genotype and T allele may provide protection against this disease.

Human genetics and genomics a decade after the release of the draft sequence of the human genome

Substantial progress has been made in human genetics and genomics research over the past ten years since the publication of the draft sequence of the human genome in 2001. Findings emanating directly from the Human Genome Project, together with those from follow-on studies, have had an enormous impact on our understanding of the architecture and function of the human genome. Major developments have been made in cataloguing genetic variation, the International HapMap Project, and with respect to advances in genotyping technologies. These developments are vital for the emergence of genome-wide association studies in the investigation of complex diseases and traits. In parallel, the advent of high-throughput sequencing technologies has ushered in the 'personal genome sequencing' era for both normal and cancer genomes, and made possible large-scale genome sequencing studies such as the 1000 Genomes Project and the International Cancer Genome Consortium. The high-throughput sequencing and sequence-capture technologies are also providing new opportunities to study Mendelian disorders through exome sequencing and whole-genome sequencing. This paper reviews these major developments in human genetics and genomics over the past decade.

Associations between TNFAIP3 gene polymorphisms and rheumatoid arthritis: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether tumor necrosis factor alpha inducible protein 3 (TNFAIP3) polymorphisms confer susceptibility to rheumatoid arthritis (RA) in ethnically different populations.

METHODS

The authors conducted meta-analyses on associations between the TNFAIP3 polymorphisms and RA susceptibility.

RESULT

A total of ten comparative studies were included in this meta-analysis, which showed an association between the two allele of rs6920220 and RA in all study subjects [odds ratio (OR) 1.216, 95% confidence interval (CI) 1.166-1.269, p < 1.0 × 10(-9)]. The two allele of rs6920220 was also significantly associated with RA in Europeans only (OR 1.227, 95% CI 1.175-1.282, p < 1.0 × 10(-9)). Meta-analysis revealed no association between the two allele of the rs10499194 polymorphism and RA in Europeans, but a significant association was found in Asians (OR 1.254, 95% CI 1.101-1.429, p=6.7 × 10(-4)). Furthermore, an association was found between the two allele of rs2230926 and RA in all study subjects (OR 1.390, 95% CI 1.214-2.331, p=1.9 × 10(-6)).

CONCLUSIONS

This meta-analysis confirms that the TNFAIP3 polymorphisms are associated with RA susceptibility in different ethnic groups, namely, in Europeans for rs6920220 and in Asians for rs10499194.

Genetic relationships between A20/TNFAIP3, chronic inflammation and autoimmune disease

A20 [also known as TNFAIP3 (tumour necrosis factor α-induced protein 3)] restricts and terminates inflammatory responses through modulation of the ubiquitination status of central components in NF-κB (nuclear factor κB), IRF3 (interferon regulatory factor 3) and apoptosis signalling cascades. The phenotype of mice with full or conditional A20 deletion illustrates that A20 expression is essential to prevent chronic inflammation and autoimmune pathology. In addition, polymorphisms within the A20 genomic locus have been associated with multiple inflammatory and autoimmune disorders, including SLE (systemic lupus erythaematosis), RA (rheumatoid arthritis), Crohn's disease and psoriasis. A20 has also been implicated as a tumour suppressor in several subsets of B-cell lymphomas. The present review outlines recent findings that illustrate the effect of A20 defects in disease pathogenesis and summarizes the identified A20 polymorphisms associated with different immunopathologies.

Insight from genome-wide association studies in rheumatoid arthritis and multiple sclerosis

Autoimmune diseases are caused by multiple genes and environmental effects. In addition, genetic contributions and the number of associated genes differ among different diseases and ethnic populations. Genome-wide association studies (GWAS) on rheumatoid arthritis (RA) and multiple sclerosis (MS) show that these diseases share many genetic factors. Recently, in addition to the major histocompatibility complex (MHC) gene, other genetic loci have been found to be associated with the risk for autoimmune diseases. This review focuses on the search for genetic variants that influence the susceptibility to RA and MS as typical autoimmune diseases and discusses the future of GWAS.