[Show abstract][Hide abstract] ABSTRACT: Family studies have provided overwhelming evidence for an underlying genetic component to psoriasis. Toll-like receptors (TLRs) are key transmembrane proteins in both the innate and adaptive immune responses which are known to be integral processes in psoriasis. Recent functional studies support this notion having suggested a role for TLR4 in the pathogenesis of psoriasis. Furthermore a missense polymorphism in the TLR4 gene has been associated with a number of autoimmune conditions, including Crohn diseases, making TLR4 a viable candidate gene for investigation. The aim of this study was to investigate polymorphisms across the TLR4 region with a high-density single nucleotide polymorphism (SNP) panel in a large cohort of patients with chronic plaque type psoriasis. Twenty SNPs were successfully genotyped using Sequenom iPLEX Gold platform in 2826 UK chronic plaque type psoriasis patients including subgroup data on presence of confirmed psoriatic arthritis (n = 1839) and early-onset psoriasis (n = 1466) was available. Allele frequencies for psoriasis patients were compared against imputed Wellcome Trust Case Control Consortium controls (n = 4861). Significant association was observed between a missense variant rs4986790 of TLR4 (Asp229Gly) and plaque type psoriasis (p = 2 × 10−4) which was also notable in those with psoriatic arthritis (p = 2 × 10−4) and early-onset psoriasis (p = 8 × 10−4). We present data suggestive of an association between a functional variant and an intronic variant of TLR4 and chronic plaque type psoriasis and psoriatic arthritis. However, validation of this association in independent cohorts will be necessary.
Full-text · Article · Feb 2016 · Archives for Dermatological Research
[Show abstract][Hide abstract] ABSTRACT: Genome-wide association studies have been tremendously successful in identifying genetic variants associated with complex diseases. The majority of association signals are intergenic and evidence is accumulating that a high proportion of signals lie in enhancer regions. We use Capture Hi-C to investigate, for the first time, the interactions between associated variants for four autoimmune diseases and their functional targets in B-and T-cell lines. Here we report numerous looping interactions and provide evidence that only a minority of interactions are common to both B-and T-cell lines, suggesting interactions may be highly cell-type specific; some disease-associated SNPs do not interact with the nearest gene but with more compelling candidate genes (for example, FOXO1, AZI2) often situated several megabases away; and finally, regions associated with different autoimmune diseases interact with each other and the same promoter suggesting common autoimmune gene targets (for example, PTPRC, DEXI and ZFP36L1).
No preview · Article · Nov 2015 · Nature Communications
[Show abstract][Hide abstract] ABSTRACT: Objectives:
A recent study identified 16 genetic variants associated with N-glycosylation of human IgG. Several of the genomic regions where these single nucleotide polymorphisms (SNPs) reside have also been associated with autoimmune disease (AID) susceptibility, suggesting there may be pleiotropy (genetic sharing) between loci controlling both N-glycosylation and AIDs. We investigated this by testing variants associated with levels of IgG N-glycosylation for association with rheumatoid arthritis (RA) susceptibility using a Mendelian randomisation study, and testing a subset of these variants in a less well-powered study of treatment response and severity.
SNPs showing association with IgG N-glycosylation were analysed for association with RA susceptibility in 14 361 RA cases and 43 923 controls. Five SNPs were tested for association with response to anti-tumour necrosis factor (TNF) therapy in 1081 RA patient samples and for association with radiological disease severity in 342 patients.
Only one SNP (rs9296009) associated with N-glycosylation showed an association (p=6.92×10(-266)) with RA susceptibility, although this was due to linkage disequilibrium with causal human leukocyte antigen (HLA) variants. Four regions of the genome harboured SNPs associated with both traits (shared loci); although statistical analysis indicated that the associations observed for the two traits are independent. No SNPs showed association with response to anti-TNF therapy. One SNP rs12342831 was modestly associated with Larsen score (p=0.05).
In a large, well-powered cohort of RA patients, we show SNPs driving levels of N-glycosylation have no association with RA susceptibility, indicating colocalisation of associated SNPs are not necessarily indicative of a shared genetic background or a role for glycosylation in disease susceptibility.
Preview · Article · Sep 2015 · Annals of the rheumatic diseases
[Show abstract][Hide abstract] ABSTRACT: TYK2 is a common genetic risk factor for several autoimmune diseases. This gene encodes a protein kinase involved in interleukin 12 (IL-12) pathway, which is a well-known player in the pathogenesis of systemic sclerosis (SSc). Therefore, we aimed to assess the possible role of this locus in SSc.
This study comprised a total of 7103 patients with SSc and 12 220 healthy controls of European ancestry from Spain, USA, Germany, the Netherlands, Italy and the UK. Four TYK2 single-nucleotide polymorphisms (V362F (rs2304256), P1104A (rs34536443), I684S (rs12720356) and A928V (rs35018800)) were selected for follow-up based on the results of an Immunochip screening phase of the locus. Association and dependence analyses were performed by the means of logistic regression and conditional logistic regression. Meta-analyses were performed using the inverse variance method.
Genome-wide significance level was reached for TYK2 V362F common variant in our pooled analysis (p=3.08×10(-13), OR=0.83), while the association of P1104A, A928V and I684S rare and low-frequency missense variants remained significant with nominal signals (p=2.28×10(-3), OR=0.80; p=1.27×10(-3), OR=0.59; p=2.63×10(-5), OR=0.83, respectively). Interestingly, dependence and allelic combination analyses showed that the strong association observed for V362F with SSc, corresponded to a synthetic association dependent on the effect of the three previously mentioned TYK2 missense variants.
We report for the first time the association of TYK2 with SSc and reinforce the relevance of the IL-12 pathway in SSc pathophysiology.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Full-text · Article · Sep 2015 · Annals of the rheumatic diseases
[Show abstract][Hide abstract] ABSTRACT: Objectives:
The current knowledge of the influence of systemic sclerosis (SSc) risk loci in the clinical sub-phenotypes is still limited. The main limitation lies in the low frequency of some sub-phenotypes which could be solved by replication studies in independent cohorts and meta-analysis between studies. In this regard, CCR6 gene variants have been recently associated with anti-topoisomerase I positive (ATA+) production in SSc patients in a candidate gene study. This gene has been proposed to have a critical role in IL-17-driven autoimmunity in human diseases.
In order to confirm the association between CCR6 and ATA+ SSc patients, we performed an independent replication study in populations of European ancestry. We studied two CCR6 genetic variants (rs968334 and rs3093024) in a total of 901 ATA+ SSc cases, 3,258 ATA- SSc cases and 7,865 healthy controls and compared allelic frequencies for those SNPs in ATA+ SSc with healthy controls and also with ATA- SSc patients.
The comparison performed between ATA+ SSc patients and healthy controls showed significant association with SNP rs968334 (p=4.88 x 10-2, OR=1.11). When we compared ATA+ SSc cases with ATA- SSc, both SNPs, rs3093024 and rs968334, showed significant associations (p=2.89 x 10-2, OR=1.13; p=1.69 x 10-2, OR=1.15). Finally, in order to increase even more sample size and statistical power, we meta-analysed our study with the previous reported and found a significant association between SNP rs3093024 and ATA+ SSc patients (p=1.00 x 10-4, OR=1.16) comparing with healthy controls.
Our work confirms the association of CCR6 gene and ATA+ SSc patients.
Full-text · Article · Aug 2015 · Clinical and experimental rheumatology
[Show abstract][Hide abstract] ABSTRACT: Human leukocyte antigen (HLA) genes confer substantial risk for autoimmune diseases on a log-additive scale. Here we speculated that differences in autoantigen-binding repertoires between a heterozygote's two expressed HLA variants might result in additional non-additive risk effects. We tested the non-additive disease contributions of classical HLA alleles in patients and matched controls for five common autoimmune diseases: rheumatoid arthritis (ncases = 5,337), type 1 diabetes (T1D; ncases = 5,567), psoriasis vulgaris (ncases = 3,089), idiopathic achalasia (ncases = 727) and celiac disease (ncases = 11,115). In four of the five diseases, we observed highly significant, non-additive dominance effects (rheumatoid arthritis, P = 2.5 × 10(-12); T1D, P = 2.4 × 10(-10); psoriasis, P = 5.9 × 10(-6); celiac disease, P = 1.2 × 10(-87)). In three of these diseases, the non-additive dominance effects were explained by interactions between specific classical HLA alleles (rheumatoid arthritis, P = 1.8 × 10(-3); T1D, P = 8.6 × 10(-27); celiac disease, P = 6.0 × 10(-100)). These interactions generally increased disease risk and explained moderate but significant fractions of phenotypic variance (rheumatoid arthritis, 1.4%; T1D, 4.0%; celiac disease, 4.1%) beyond a simple additive model.
[Show abstract][Hide abstract] ABSTRACT: Determining whether potential causal variants for related diseases are shared can identify overlapping etiologies of multifactorial disorders. Colocalization methods disentangle shared and distinct causal variants. However, existing approaches require independent data sets. Here we extend two colocalization methods to allow for the shared-control design commonly used in comparison of genome-wide association study results across diseases. Our analysis of four autoimmune diseases-type 1 diabetes (T1D), rheumatoid arthritis, celiac disease and multiple sclerosis-identified 90 regions that were associated with at least one disease, 33 (37%) of which were associated with 2 or more disorders. Nevertheless, for 14 of these 33 shared regions, there was evidence that the causal variants differed. We identified new disease associations in 11 regions previously associated with one or more of the other 3 disorders. Four of eight T1D-specific regions contained known type 2 diabetes (T2D) candidate genes (COBL, GLIS3, RNLS and BCAR1), suggesting a shared cellular etiology.
[Show abstract][Hide abstract] ABSTRACT: Background Systemic sclerosis (SSc) is a chronic connective tissue disorder with the highest mortality of any autoimmune disease. SSc is a complex disease with a clear genetic component. This genetic susceptibility has been supported by a number of well-powered genetic association studies. In this regard, it is remarkable that several SSc genetic markers have been reported in the IL-12 pathway (IL12A, STAT4, IL12RB2, IL12RB1). Furthermore, multiple clinical and experimental evidences have shown that this pathway is altered in SSc patients. TYK2 encodes the Tyrosine kinase 2 enzyme, which mediates the signaling of IL-12 receptor.
Objectives We aimed to analyze the association of the TYK2 locus with SSc susceptibility.
Methods The complete set of individuals included in this study reached 4,985 SSc patients and 11,621 healthy controls of European ancestry from Spain, Germany, The Netherlands, USA, Italy and United Kingdom. Initially, we analyzed all the polymorphisms located in the region that encompasses the TYK2 coding sequence and 20 kb up and downstream, in a previously published Immunochip-based dense genotyping study. We identified a common single nucleotide polymorphism (SNP), the V362F variant (rs2304256) and three rare variants: P1104A (rs34536443), A928V (rs35018800) and I684S (rs12720356), as the genetic markers that better explained the observed association in the region. Then, these variants were followed up in additional cohorts. Association and dependence relations were tested using logistic regression and conditional logistic regression, and pooled analyses were performed using the inverse variance method.
Results Our pooled analysis showed that V362F variant reached the genome-wide significance level (P=2.00x10-10, OR =0.84), while P1104A (rs34536443), A928V (rs35018800) and I684S (rs12720356) remained significant (P=8.61x10-3, OR=0.79; P=1.95x10-4, OR=0.49; Prandom=0.016, OR=0.84, respectively). The analyses carried out for the main clinical features revealed that the observed association signals relied on the whole disease. Furthermore, our results revealed that the association of TYK2 with SSc was dependent on the interaction between the P1104A, A928V and I684S rare variants and that the previously observed association for the autoimmune related V362F variant, corresponded to a synthetic association dependent on the association of the three previously mentioned rare variants.
Conclusions We report for the first time the association of TYK2 variants with SSc. Moreover, our data support that the highly significant association of a previously known autoimmune disease marker, the V362F variant (rs2304256), is dependent on the effect of three non-synonymous rare variants in this locus.
Disclosure of Interest None declared
No preview · Article · Jun 2015 · Annals of the Rheumatic Diseases
[Show abstract][Hide abstract] ABSTRACT: Advances have been made in identifying genetic susceptibility loci for autoimmune diseases, but evidence is needed regarding their association with prognosis and treatment response.
To assess whether specific HLA-DRB1 haplotypes associated with rheumatoid arthritis (RA) susceptibility are also associated with radiological severity, mortality, and response to tumor necrosis factor (TNF) inhibitor drugs.
The Norfolk Arthritis Register (NOAR; 1691 patients and 2811 radiographs; recruitment: 1989-2008; 2008 as final follow-up) was used as a discovery cohort and the Early Rheumatoid Arthritis Study (421 patients and 3758 radiographs; recruitment: 1986-1999; 2005 as final follow-up) as an independent replication cohort for studies of radiographic outcome. Mortality studies were performed in the NOAR cohort (2432 patients; recruitment: 1990-2007; 2011 as final follow-up) and studies of treatment response in the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate cohort (1846 patients enrolled at initiation of TNF inhibitor; recruitment: 2006-2010; 2011 as final follow-up). Longitudinal statistical modeling was performed to integrate multiple radiograph records per patient over time. All patients were from the United Kingdom and had self-reported white ancestry.
Sixteen HLA-DRB1 haplotypes defined by amino acids at positions 11, 71, and 74.
Radiological outcome using the Larsen score (range: 0 [none] to 200 [severe joint damage]) and erosions of the hands and feet on radiographs, all-cause mortality, and treatment response measured by change in Disease Activity Score based on 28 joint counts and European League Against Rheumatism (EULAR) response.
Patients with RA and valine at position 11 of HLA-DRB1 had the strongest association with radiological damage (OR, 1.75 [95% CI, 1.51-2.05], P = 4.6E-13). By year 5, the percentages of patients with erosions of the hands and feet were 48% of noncarriers (150/314) of valine at position 11, 61% of heterozygote carriers (130/213), and 74% of homozygote carriers (43/58). Valine at position 11 also was associated with higher all-cause mortality in patients with inflammatory polyarthritis (hazard ratio, 1.16 [95% CI, 1.03-1.31], P = .01) (noncarriers: 319 deaths in 1398 patients over 17 196 person-years, mortality rate of 1.9% per year; carriers: 324 deaths in 1116 patients in 13 208 person-years, mortality rate of 2.5% per year) and with better EULAR response to TNF inhibitor therapy (OR, 1.14 [95% CI, 1.01-1.30], P = .04) (noncarriers: 78% [439/561 patients] with moderate or good EULAR response; heterozygote carriers: 81% [698/866]; and homozygote carriers: 86% [277/322]). The risk hierarchy defined by HLA-DRB1 haplotypes was correlated between disease susceptibility, severity, and mortality, but inversely correlated with TNF inhibitor treatment response.
Among patients with RA, the HLA-DRB1 locus, which is associated with disease susceptibility, was also associated with radiological severity, mortality, and treatment response. Replication of these findings in other cohorts is needed as a next step in evaluating the role of HLA-DRB1 haplotype analysis for management of RA.
Full-text · Article · Apr 2015 · JAMA The Journal of the American Medical Association
[Show abstract][Hide abstract] ABSTRACT: Genome-wide association studies (GWASs) have been used to great effect to identify genetic susceptibility loci for complex disease. A series of GWAS and meta-analyses have informed the discovery of over 100 loci for rheumatoid arthritis (RA). In common with findings in other autoimmune diseases the lead signals for the majority of these loci do not map to known gene sequences. In order to realise the benefit of investment in GWAS studies it is vital we determine how disease associated alleles function to influence disease processes. This is leading to rapid development in our knowledge as to the function of non-coding regions of the genome. Here we consider possible functional mechanisms for intergenic RA-associated variants which lie within lncRNA sequences.
[Show abstract][Hide abstract] ABSTRACT: Despite the success of genome-wide association studies (GWAS) in detecting a large number of loci for complex phenotypes such as rheumatoid arthritis (RA) susceptibility, the lack of information on the causal genes leaves important challenges to interpret GWAS results in the context of the disease biology. Here, we genetically fine-map the RA risk locus at 19p13 to define causal variants, and explore the pleiotropic effects of these same variants in other complex traits. First, we combined Immunochip dense genotyping (n = 23,092 case/control samples), Exomechip genotyping (n = 18,409 case/control samples) and targeted exon-sequencing (n = 2,236 case/controls samples) to demonstrate that three pro-tein-coding variants in TYK2 (tyrosine kinase 2) independently protect against RA: P1104A (rs34536443, OR = 0.66, P = 2.3×10-21), A928V (rs35018800, OR = 0.53, P = 1.2×10-9), and I684S (rs12720356, OR = 0.86, P = 4.6×10-7). Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6×10-18 ), and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V) may also protect against inflammatory bowel disease (IBD; Pomnibus = 0.005). Finally, in a phenomewide association study (PheWAS) assessing >500 phenotypes using electronic medical records (EMR) in >29,000 subjects, we found no convincing evidence for association of P1104A and A928V with complex phenotypes other than autoimmune diseases such as RA, SLE and IBD. Together, our results demonstrate the role of TYK2 in the pathogenesis of RA, SLE and IBD, and provide supporting evidence for TYK2 as a promising drug target for the treatment of autoimmune diseases.
[Show abstract][Hide abstract] ABSTRACT: Many of the hits identified through genome-wide association studies are located outside protein-coding regions, making it difficult to define mechanism. In Nature, Farh etal., (2014) describe an approach to identify causal variants in autoimmune disease as first step to assigning function. Many of the hits identified through genome-wide association studies are located outside protein-coding regions, making it difficult to define mechanism. In Nature, Farh and colleagues describe an approach to identify causal variants in autoimmune disease as first step to assigning function.
[Show abstract][Hide abstract] ABSTRACT: A large portion of common variant loci associated with genetic risk for schizophrenia reside within noncoding
sequence of unknown function. Here, we demonstrate promoter and enhancer enrichment in schizophrenia variants associated with expression quantitative trait loci (eQTL). The enrichment is greater when functional annotations derived from the human brain are used relative to peripheral tissues. Regulatory trait concordance analysis ranked genes within schizophrenia genome-wide significant loci for a potential functional role, based on colocalization of a risk SNP, eQTL, and regulatory element sequence. We identified potential physical interactions of noncontiguous proximal and distal regulatory elements. This was verified in prefrontal cortex and -induced pluripotent stem cell–derived neurons for the L-type calciumchannel (CACNA1C) risk locus. Our findings point to a functional link between schizophrenia-associated noncoding SNPs and 3D genome architecture associated with chromosomal loopings and transcriptional regulation in the brain.
[Show abstract][Hide abstract] ABSTRACT: There is now a general consensus that RA has a spectrum of disease stages that can begin many years before the onset of clinical
symptoms. It is widely thought that understanding the complex interplay between genetics and environment, and their role in
pathogenesis, is essential in gaining further insight into the mechanisms that drive disease development and progression.
More than 100 genetic susceptibility loci have now been identified for RA through studies that have focused on patients with
established RA compared with healthy controls. Studying the early preclinical phases of disease will provide valuable insights
into the biological events that precede disease and could potentially identify biomarkers to predict disease onset and future
therapeutic targets. In this review we will cover recent advances in the knowledge of genetic and environmental risk factors
and speculate on how these factors may influence the transition from one stage of disease to another.
[Show abstract][Hide abstract] ABSTRACT: Objective
Lumbar spinal stenosis is one of the most commonly diagnosed spinal disorders in older adults. Although the pathophysiology of the clinical syndrome is not well understood, a narrow central canal or intervertebral foramen is an essential or defining feature. The aim of the present study was to estimate the magnitude of genetic versus environmental influences on central lumbar spinal stenosis and to investigate disc degeneration and stature or bone development as possible genetic pathways. MethodsA classic twin study with multivariate analyses considering lumbar level and other covariates was conducted. The study sample comprised 598 male twins (147 monozygotic and 152 dizygotic pairs), 35-70 years of age, from the population-based Finnish Twin Cohort. The primary phenotypes were central lumbar stenosis as assessed qualitatively on magnetic resonance imaging (MRI) and quantitatively measured dural sac cross-sectional area. Additional phenotypes (to examine possible genetic pathways) included disc bulging and standing height, as an indicator of overall skeletal size or development. ResultsThe heritability estimate (h(2)) for qualitatively assessed central lumbar spinal stenosis on MRI was 66.9% (95% confidence interval [95% CI] 56.8, 74.5). The broad-sense heritability estimate for dural sac cross-sectional area was 81.2% (95% CI 74.5, 86.1), with a similar magnitude of genetic influences across lumbar levels (h(2) = 72.4-75.6). The additive genetic correlation of quantitatively assessed stenosis and disc bulging was extremely high. There was no indication of shared genetic influences between stenosis and stature. Conclusion
Central lumbar spinal stenosis and associated dural sac dimensions are highly genetic, and disc degeneration (bulging) appears to be one pathway through which genes influence spinal stenosis.
Full-text · Article · Sep 2014 · Arthritis and Rheumatology
[Show abstract][Hide abstract] ABSTRACT: Background Anti-TNF therapies have proved a huge advance for the treatment of rheumatoid arthritis (RA), however very good disease control or remission is achieved in just 30% of patients. This makes the identification of biomarkers predictive of response an important area of research. Such predictive biomarkers would allow the most effective treatment for a patient to be identified early in disease course. An increasing number of studies have identified a role for epigenetics in RA and other autoimmune disorders, thus we hypothesised that epigenetic changes, such as DNA methylation, may provide potential biomarkers of response to anti-TNFs.
Objectives To identify methylation signatures predictive of response to anti-TNF therapies in patients with RA.
Methods Patients were selected from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate (BRAGGSS) longitudinal cohort. Patients (n=119) were selected based on having an extreme response phenotype after 3 months of treatment with etanercept or adalimumab; 36 were good responders to etanercept and 30 to adalimumab defined as having an endpoint DAS28<2.6, and 35 were poor responders to etanercept and 18 to adalimumab defined as having an improvement of <0.6 or between 0.6-1.2 with an endpoint DAS28 of >5.1. DNA from each patient, sampled before initiation of therapy, was bisulfite converted and an epigenome-wide association study was conducted using the HumanMethylation450 BeadChip (Illumina). The results from each drug were analysed separately using the minfi package in R and probes with a detection-p value >0.01 were removed. Differentially methylated positions between responders and non-responders were identified using the F-test following quantile normalisation.
Results In the etanercept study, four CpG sites showed differential DNA methylation that passed a false discovery rate of 0.05, while in the adalimumab study, two CpG sites passed this threshold. The most differentially methylated position in etanercept patients mapped to the LRPAP1 gene (p=1.46×10-8). This gene encodes a chaperone of low density lipoprotein receptor-related protein 1 (LRP1) which is known to influence TGF-β activity. Technical validation of methylation at this site by pyrosequencing showed very good correlation (Spearmans r=0.8). In the adalimumab patients, the most differentially methylated position maps to the MAD2L2 gene.
Conclusions This is one of the largest methylome-wide investigations of treatment response to anti-TNF therapies in RA. These preliminary results identify DNA methylation as a potential biomarker of response for etanercept and adalimumab.
Acknowledgements This work was supported by the innovative medicines initiative joint undertaking (IMI JU) funded project BeTheCure, (contract number 115142-2).
Disclosure of Interest None declared
No preview · Article · Jun 2014 · Annals of the Rheumatic Diseases