Twins concordant for juvenile rheumatoid arthritis

Thyroid function in pediatric patients with juvenile idiopathic arthritis

PURPOSE

Juvenile Idiopathic Arthritis (JIA) is a chronic inflammatory disease characterized by chronic synovitis, sometimes associated with fever, rash, pericarditis and uveitis. Limited data are available concerning autoimmune diseases associated with JIA in childhood.

THE AIMS OF OUR STUDY WERE

(a) evaluating the thyroid function in a group of Italian children affected by JIA; (b) identifying which Autoimmune Thyroid Diseases (ATDs) are related to JIA in this population.

METHODS

A population of 51 patients with JIA was investigated. Each patient enrolled was evaluated clinically (family history for Autoimmune Diseases (ADs), personal history and physical examination). In the sample were evaluated thyroid function, inflammation's index and anti-thyroid antibodies.

RESULTS

The 68.6% (35) of our patients had the oligoarticular form, 27.5% (14) had the polyarticular one, 2% (1) had systemic onset and 2% (1) had undifferentiated arthritis. We focused our attention on the differences between the first two forms. We did not find any difference on the gender prevalence (p > 0.05). A higher presence of anti-TPO antibodies was found in the polyarticular form, with a significant difference with the oligoarticular one (p = 0.032). We researched the anti-hTG antibodies (p > 0.05) and ANA for each group (p > 0.05). We found a significant prevalence of family history for ADs in the polyarticular form (p < 0.05).

CONCLUSION

Our findings show the necessity to focus on thyroid function in patients with JIA. Although the oligoarticular form is the most frequent, the polyarticular form shows a higher frequency of thyroid function's alteration. This suggests the need for specific attention in polyarticular form.

Genetic variant in SPAG16 is associated with the susceptibility of ACPA-positive rheumatoid arthritis possibly via regulation of MMP-3

OBJECTIVES

In two previously published genome-wide association studies, a cluster of variants of sperm-associated antigen16 (SPAG16) were reported to be associated with the radiological progression rate of ACPA-positive rheumatoid arthritis (RA) patients from North American and Southern European ancestry. In this study, we aimed to investigate whether the reported RA-risk loci in SPAG16 are associated with the disease in the Chinese population and to further validate the functional role of the susceptible locus in RA tissues.

METHODS

A total of 500 ACPA-positive RA patients and 1000 age-matched healthy subjects were recruited. Two SNPs of SPAG16, including rs7607479 (C/T) and rs6435818 (A/C), were genotyped, and the genotyping data were compared with chi-square test. Gene expression analysis was performed in synovial tissues obtained from 40 RA patients and 30 non-RA controls surgically treated for bone fracture. The tissue expression of SPAG16 and matrix metalloproteinase 3 (MMP-3) was compared between the two groups by the Student's t test. The relationship between serum indexes and mRNA expression of SPAG16 and MMP-3 were evaluated by Spearman's correlation analysis.

RESULT

For rs7607479, the frequency of genotype TT was significantly higher in RA patients than in the controls (49.0% vs. 40.4%, p = 0.002). The RA patients were found to have significantly lower frequency of allele C than the controls (30.9% vs. 36.8%, p = 0.001). As for rs6435818, there was no significant difference of genotype or allele frequency between the two groups. The mRNA expression of MMP-3 was 1.63-fold higher in the RA patients than in the controls (p < 0.001). The expression of SPAG16 was comparable between the two groups (p = 0.43). The mRNA expression of MMP-3 was 1.39-fold higher in patients with genotype TT than in the patients with genotype CC (p = 0.006). The mRNA expression level of MMP-3 was significantly correlated with serum rheumatoid factor (r = 0.498, p < 0.001) and C-reactive protein (r = 0.272, p = 0.01), weakly correlated with erythrocyte sedimentation rate (r = 0.236, p = 0.09).

CONCLUSIONS

We validated a common genetic risk factor in ACPA-positive patients with RA, which is associated with the tissue production of MMP-3 and disease progression. Further functional analysis into the role of rs7607479 in MMP-3 expression can shed new light on the genetic architecture of ACPA-positive RA.

A Cross-Tissue Transcriptome-Wide Association Study Identifies Novel Susceptibility Genes for Juvenile Idiopathic Arthritis in Asia and Europe

Background

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in children, and its pathogenesis is still unclear. Genome-wide association studies (GWASs) of JIA have identified hundreds of risk factors, but few of them implicated specific biological mechanisms.

Methods

A cross-tissue transcriptome-wide association study (TWAS) was performed with the functional summary-based imputation software (FUSION) tool based on GWAS summary datasets (898 JIA patients and 346,102 controls from BioBank Japan (BBJ)/FinnGen). The gene expression reference weights of skeletal muscle and the whole blood were obtained from the Genotype-Tissue Expression (GTExv8) project. JIA-related genes identified by TWAS findings genes were further compared with the differentially expressed genes (DEGs) identified by the mRNA expression profile of JIA from the Gene Expression Omnibus (GEO) database (accession number: GSE1402). Last, candidate genes were analyzed using functional enrichment and annotation analysis by Metascape to examine JIA-related gene sets.

Results

The TWAS identified 535 significant genes with P < 0.05 and contains 350 for Asian and 195 for European (including 10 genes both expressed in Asian and European), such as CDC16 (P = 1.72E-03) and PSMD5-AS1 (P = 3.65E-02). Eight overlapping genes were identified based on TWAS results and DEGs of JIA patients, such as SIRPB1 (P_TWAS = 4.21E-03, P_DEG = 1.50E-04) and FRAT2 (P_TWAS = 2.82E-02, P_DEG = 1.43E-02). Pathway enrichment analysis of TWAS identified 183 pathways such as cytokine signaling in the immune system and cell adhesion molecules. By integrating the results of DEGs pathway and process enrichment analyses, 19 terms were identified such as positive regulation of T-cell activation.

Conclusion

By conducting two populations TWAS, we identified a group of JIA-associated genes and pathways, which may provide novel clues to uncover the pathogenesis of JIA.

SLAMF6 is associated with the susceptibility and severity of rheumatoid arthritis in the Chinese population

OBJECTIVES

A recently published genome-wide association study identified six novel loci associated with rheumatoid arthritis (RA) in Korean population. We aimed to investigate whether these newly reported RA-risk loci are associated with RA in the Chinese population and to further characterize the functional role of the susceptible gene.

METHODS

The susceptible variants of RA were genotyped in 600 RA patients and 800 healthy controls, including rs148363003 of SLAMF6, rs117605225 of CXCL13, rs360136 of SWAP70, rs111597524 of NFKBIA, rs194757 of ZFP36L1 and rs1547233 of LINC00158. Synovial tissues were collected from the knee joint of 50 RA patients and 40 controls without osteoarthritis for the gene expression analysis. Inter-group comparisons were performed with the Chi-square test for genotyping data or with Student's t-test for gene expression analysis.

RESULT

For rs148363003 of SLAMF6, RA patients were observed to have a significantly lower frequency of genotype CC (4.5% vs. 0.9%, p = 0.004) as compared with the controls. The frequency of allele C was remarkably higher in the patients than in the controls (11.5% vs. 8.0%, p = 0.002), with an odds ratio of 1.49 (95% CI = 1.16-1.92). There was no significant difference between the patients and the controls regarding genotype or allele frequency of the other 5 variants. The mRNA expression of SLAMF6 was 1.6 folds higher in the RA patients than in the controls. Moreover, SLAMF6 expression was 1.5 folds higher in patients with genotype CC than in the patients with genotype TT.

CONCLUSIONS

SLAMF6 was associated with both the susceptibility and severity of RA in the Chinese population. Moreover, rs148363003 could be a functional variant regulating the tissue expression of SLAMF6 in RA patients. It is advisable to conduct further functional analysis for a comprehensive knowledge on the contribution of this variant to the development of RA.

Biological classification of childhood arthritis: roadmap to a molecular nomenclature

Chronic inflammatory arthritis in childhood is heterogeneous in presentation and course. Most forms exhibit clinical and genetic similarity to arthritis of adult onset, although at least one phenotype might be restricted to children. Nevertheless, paediatric and adult rheumatologists have historically addressed disease classification separately, yielding a juvenile idiopathic arthritis (JIA) nomenclature that exhibits no terminological overlap with adult-onset arthritis. Accumulating clinical, genetic and mechanistic data reveal the critical limitations of this strategy, necessitating a new approach to defining biological categories within JIA. In this Review, we provide an overview of the current evidence for biological subgroups of arthritis in children, delineate forms that seem contiguous with adult-onset arthritis, and consider integrative genetic and bioinformatic strategies to identify discrete entities within inflammatory arthritis across all ages.

CD4+ T cells from children with active juvenile idiopathic arthritis show altered chromatin features associated with transcriptional abnormalities

Juvenile idiopathic arthritis (JIA) is one of the most common chronic diseases in children. While clinical outcomes for patients with juvenile JIA have improved, the underlying biology of the disease and mechanisms underlying therapeutic response/non-response are poorly understood. We have shown that active JIA is associated with distinct transcriptional abnormalities, and that the attainment of remission is associated with reorganization of transcriptional networks. In this study, we used a multi-omics approach to identify mechanisms driving the transcriptional abnormalities in peripheral blood CD4+ T cells of children with active JIA. We demonstrate that active JIA is associated with alterations in CD4+ T cell chromatin, as assessed by ATACseq studies. However, 3D chromatin architecture, assessed by HiChIP and simultaneous mapping of CTCF anchors of chromatin loops, reveals that normal 3D chromatin architecture is largely preserved. Overlapping CTCF binding, ATACseq, and RNAseq data with known JIA genetic risk loci demonstrated the presence of genetic influences on the observed transcriptional abnormalities and identified candidate target genes. These studies demonstrate the utility of multi-omics approaches for unraveling important questions regarding the pathobiology of autoimmune diseases.

Juvenile Idiopathic Arthritis for the Pediatric Orthopedic Surgeon

Juvenile idiopathic arthritis includes conditions characterized by joint inflammation of unknown etiology lasting longer than 6 weeks in patients younger than 16 years. Diagnosis and medical management are complex and best coordinated by a pediatric rheumatologist. The mainstay of therapy is anti-inflammatory and biologic medications to control pain and joint inflammation. Orthopedic surgical treatment may be indicated for deformity, limb length inequality, or end-stage arthritis. Evaluation of the cervical spine and appropriate medication management in consultation with a patient's rheumatologist are essential in perioperative care. Preoperative planning should take into account patient deformity, contracture, small size, osteopenia, and medical comorbidities.

Recent advances in our understanding of the pathogenesis of juvenile idiopathic arthritis and their potential clinical implications

INTRODUCTION

Juvenile idiopathic arthritis (JIA) comprises systemic and non-systemic forms of chronic childhood arthritis diagnosed prior to age 16. Significant improvement in treatment outcomes has been witnessed since the introduction of biologics. In particular, advances in research in the area of multidimensional interrogation and network analysis have facilitated understanding of the complex cacophony of components orchestrating disease immunopathogenesis. Areas covered: In this review, we will examine the scientific advances that have augmented our understanding of JIA pathogenesis, focusing on the progress made in systemic, poly, and oligo JIA in four major aspects: (a) unraveling the pathogenic mechanisms, (b) disease classification, (c) therapeutic selection, and (d) decision for withdrawal of medications after achieving remission. Expert commentary: Dysregulation of innate immune cell physiology and function in sJIA will be highlighted. MicroRNAs contribute to monocyte/macrophage polarization with resulting consequences on macrophage activation syndrome development. The involvement of neutrophils, a major source of S100A8/9/12, in the active inflammatory phase of sJIA is compelling. In non-sJIA, circulating CD4 subsets in T effector and regulatory compartments possessing a strong synovial T-cell receptor coverage and disease activity correlation, acted as an accessible reservoir of pathogenic cells exploitable for clinical management.

Update on research and clinical translation on specific clinical areas from biology to bedside: Unpacking the mysteries of juvenile idiopathic arthritis pathogenesis

In the past decades, we have gained important insights into the mechanisms of disease and therapy underlying chronic inflammation in juvenile idiopathic arthritis (JIA). These insights have resulted in several game-changing therapeutic modalities for many patients. However, additional progress still has to be made with regard to efficacy, cost reduction, minimization of side effects, and dose-tapering and stop strategies of maintenance drugs. Moreover, to really transform the current therapeutic strategies into personalized medicine, we need validated biomarkers to translate increased insights into clinical practice. In this article, we describe recent developments in JIA research and outline how clinical innovations need to go hand in hand with basic discoveries to really effect care for patients. Facilitating the transition from bench to bedside is crucial for addressing the major current challenges in JIA management. When successful, it will set new standards for a safe, targeted, and personalized medicine in JIA.

A scoping review on the study of siblings in pediatric pain

Background: Sibling relationships are longstanding across an individual’s life and are influential in children’s development. The study of siblings in pediatric pain is, although in early stages, a growing field.

Aims: This scoping review sought to summarize and map the type of research available examining siblings and pediatric pain to identify gaps and directions for future research.

Methods: Studies were identified based on a search of PubMed, CINAHL, PsycInfo, Embase, and Web of Science (up to November 2016). We extracted data about study methods, the sample, outcome assessment, and the influence/relationships investigated.

Results: Thirty-five studies were included. Most studies used quantitative methods (n = 28), and participants typically included children (i.e., aged 6–12; n = 24) and adolescents (i.e., aged 13–18; n = 18). The majority of studies examined siblings in the context of chronic and disease-related pain (n = 30). Though quantitative studies primarily focused on the genetic influence of pain conditions (n = 18), qualitative and mixed-methods studies typically focused on exploring the impact of siblings with and without pain on one another (n = 2) and the impact of pain on the broader dyadic relationship/functioning (n = 4).

Conclusions: Sibling research in pediatric pain has been primarily focused on the biological/physical components of pain, using quantitative approaches. Conducting more studies using qualitative or mixed-methods designs, incorporating multiple assessment measures (e.g., observational, self-report) and multiple perspectives (e.g., siblings, health professionals), may provide an opportunity to gain richer and more comprehensive information regarding the experience of siblings.

Lack of Association between STAT4 Single Nucleotide Polymorphisms and Iranian Juvenile Rheumatoid Arthritis Patients

Juvenile rheumatoid arthritis (JRA) is a common chronic systemic autoimmune disease in children. Single nucleotide polymorphisms (SNPs) of signal transducer and activator of transcription 4 (STAT4) gene are suspected to have association with the risk of autoimmune diseases. Previous investigations have indicated that the STAT4 rs7574865 T allele was significantly associated with rheumatoid arthritis. In this study, we aimed to evaluate the association of STAT4 SNPs with JRA in Iranian population. T allele of STAT4 rs7574865 SNP was less frequent in patients than in controls, and the difference was not significant (p = 0.19, OR = 0.72, 95% CI: 0.44 -1.17). In addition, G allele of this SNP was frequent but not significant in JRA patients (p = 0.19, OR = 1.38, 95% CI: 0.85-2.25). Neither alleles nor genotypes of rs7601754 SNP of STAT4 gene demonstrated associations with JRA. We recognize that gene variants of STAT4 did not affect JRA susceptibility in Iranian population.

Epipolymorphisms associated with the clinical outcome of autoimmune arthritis affect CD4+ T cell activation pathways

Multifactorial diseases, including autoimmune juvenile idiopathic arthritis (JIA), result from a complex interplay between genetics and environment. Epigenetic mechanisms are believed to integrate such gene-environment interactions, fine-tuning gene expression, and possibly contributing to immune system dysregulation. Although anti-TNF therapy has strongly increased JIA remission rates, it is not curative and up to 80% of patients flare upon treatment withdrawal. Thus, a crucial unmet medical and scientific need is to understand the immunological mechanisms associated with remission or flare to inform clinical decisions. Here, we explored the CD4⁺ T-cell DNA methylome of 68 poly-articular and extended oligo-articular JIA patients, before and after anti-TNF therapy withdrawal, to identify features associated with maintenance of inactive disease. Individual CpG sites were clustered in coherent modules without a priori knowledge of their function through network analysis. The methylation level of several CpG modules, specifically those enriched in CpG sites belonging to genes that mediate T-cell activation, uniquely correlated with clinical activity. Differences in DNA methylation were already detectable at the time of therapy discontinuation, suggesting epigenetic predisposition. RNA profiling also detected differences in T-cell activation markers (including HLA-DR) but, overall, its sensitivity was lower than epigenetic profiling. Changes to the T-cell activation signature at the protein level were detectable by flow cytometry, confirming the biological relevance of the observed alterations in methylation. Our work proposes epigenetic discrimination between clinical activity states, and reveals T-cell-related biological functions tied to, and possibly predicting or causing, clinical outcome.

The human microbiome and juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in childhood. The pathogenesis of JIA is thought to be the result of a combination of host genetic and environmental triggers. However, the precise factors that determine one's susceptibility to JIA remain to be unravelled. The microbiome has received increasing attention as a potential contributing factor to the development of a wide array of immune-mediated diseases, including inflammatory bowel disease, type 1 diabetes and rheumatoid arthritis. Also in JIA, there is accumulating evidence that the composition of the microbiome is different from healthy individuals. A growing body of evidence indeed suggests that, among others, the microbiome may influence the development of the immune system, the integrity of the intestinal mucosal barrier, and the differentiation of T cell subsets. In turn, this might lead to dysregulation of the immune system, thereby possibly playing a role in the development of JIA. The potential to manipulate the microbiome, for example by faecal microbial transplantation, might then offer perspectives for future therapeutic interventions. Before we can think of such interventions, we need to first obtain a deeper understanding of the cause and effect relationship between JIA and the microbiome. In this review, we discuss the existing evidence for the involvement of the microbiome in JIA pathogenesis and explore the potential mechanisms through which the microbiome may influence the development of autoimmunity in general and JIA specifically.

Immunogenetics of juvenile idiopathic arthritis: A comprehensive review

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthropathy of childhood. Juvenile idiopathic arthritis is believed to be a complex genetic trait influenced by both genetic and environmental factors. Twin and family studies suggest a substantial role for genetic factors in the predisposition to JIA. Describing the genetics is complicated by the heterogeneity of JIA; the International League of Associations for Rheumatology (ILAR) has defined seven categories of JIA based on distinct clinical and laboratory features. Utilizing a variety of techniques including candidate gene studies, the use of genotyping arrays such as Immunochip, and genome wide association studies (GWAS), both human leukocyte antigen (HLA) and non-HLA susceptibility loci associated with JIA have been described. Several of these polymorphisms (e.g. HLA class II, PTPN22, STAT4) are shared with other common autoimmune conditions; other novel polymorphisms that have been identified may be unique to JIA. Associations with oligoarticular and RF-negative polyarticular JIA are the best characterized. A strong association between HLA DRB1:11:03/04 and DRB1:08:01, and a protective effect of DRB1:15:01 have been described. HLA DPB1:02:01 has also been associated with oligoarticular and RF-negative polyarticular JIA. Besides PTPN22, STAT4 and PTPN2 variants, IL2, IL2RA, IL2RB, as well as IL6 and IL6R loci also harbor variants associated with oligoarticular and RF-negative polyarticular JIA. RF-positive polyarticular JIA is associated with many of the shared epitope encoding HLA DRB1 alleles, as well as PTPN22, STAT4 and TNFAIP3 variants. ERA is associated with HLA B27. Most other associations between JIA categories and HLA or non-HLA variants need confirmation. The formation of International Consortia to ascertain and analyze large cohorts of JIA categories, validation of reported findings in independent cohorts, and functional studies will enhance our understanding of the genetic underpinnings of JIA.

Juvenile idiopathic arthritis

Juvenile idiopathic arthritis is a heterogeneous group of diseases characterised by arthritis of unknown origin with onset before age of 16 years. Pivotal studies in the past 5 years have led to substantial progress in various areas, ranging from disease classification to new treatments. Gene expression profiling studies have identified different immune mechanisms in distinct subtypes of the disease, and can help to redefine disease classification criteria. Moreover, immunological studies have shown that systemic juvenile idiopathic arthritis is an acquired autoinflammatory disease, and have led to successful studies of both interleukin-1 and interleukin-6 blockade. In other forms of the disease, synovial inflammation is the consequence of a disturbed balance between proinflammatory effector cells (such as T-helper-17 cells), and anti-inflammatory regulatory cells (such as FOXP3-positive regulatory T cells). Moreover, specific soluble biomarkers (S100 proteins) can guide individual treatment. Altogether these new developments in genetics, immunology, and imaging are instrumental to better define, classify, and treat patients with juvenile idiopathic arthritis.

Quantification of the familial contribution to juvenile idiopathic arthritis

OBJECTIVE

We previously demonstrated that there is familial aggregation of juvenile idiopathic arthritis (JIA). Using a large JIA cohort, we sought to identify additional clusters of JIA cases and to calculate robust estimates of the relative risk (RR) of JIA in the siblings and cousins of JIA probands. We also estimated the population attributable risk (PAR) of familial factors in JIA.

METHODS

A probabilistic record-linking analysis was performed by matching the records of 862 patients with JIA with the records of approximately 7 million individuals in the Utah Population Database (UPDB), a computerized genealogic database. For each patient, 5 control subjects matched for birth year and sex were selected from the UPDB. Specialized software was used to test for familial aggregation of disease, to estimate the magnitude of familial risks, and to identify families at high risk of disease.

RESULTS

We identified 22 founders who had significantly more descendants with JIA than expected (5-13 descendants; P values ranged from <0.0001 to <0.008). The PAR of familial factors for JIA was approximately 13%. The RR of JIA in the siblings of patients was significantly increased (11.6, 95% confidence interval [95% CI] 4.9-27.5, P < 2.59 x 10(-8)). The RR of JIA in first cousins was also increased (5.82, 95% CI 2.5-13.8, P < 6.07 x 10(-5)).

CONCLUSION

We have identified the largest sets of JIA pedigrees described to date. Approximately 13% of cases of JIA can be attributed to familial factors. Siblings and first cousins of probands with JIA have an increased risk of JIA. The observed decline in the magnitude of risk between siblings and cousins suggests that JIA is influenced by shared genetic factors.

A comprehensive review of the genetics of juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic arthropathy of childhood which is believed to be influenced by both genetic and environmental factors. The progress in identifying genes underlying JIA susceptibility using candidate gene association studies has been slow. Several associations between JIA and variants in the genes encoding the human leukocyte antigens (HLA) have been confirmed and replicated in independent cohorts. However it is clear that genetic variants outside the HLA also influence susceptibility to JIA. While a large number of non-HLA candidate genes have been tested for associations, only a handful of reported associations such as PTPN22 have been validated. In this review we discuss the principles behind genetic studies of complex traits like JIA, and comprehensively catalogue non-HLA candidate-gene association studies performed in JIA to date and review several validated associations. Most candidate gene studies are underpowered and do not detect associations, and those that do are often not replicated. We also discuss the principles behind genome-wide association studies and discuss possible implications for identifying genes underlying JIA. Finally we discuss several genetic variants underlying multiple clinically distinct autoimmune phenotypes.

Juvenile rheumatoid arthritis affected sibpairs: Extent of clinical phenotype concordance

OBJECTIVE

To investigate the clinical phenotypes and demographic characteristics of 183 affected sibling pairs (ASPs) with juvenile rheumatoid arthritis (JRA) and to determine whether there are differences between the clinical phenotypes of the ASP cohort compared with patients with sporadic disease and whether there is greater sharing of specific clinical features within versus between sibpairs.

METHODS

Details of the JRA Affected Sibpair Registry operations have been described previously. The frequencies of phenotypes in the 2 cohorts were tabulated, summary statistics were determined, and comparisons were made by chi-square test or t-test. Sibling risk, sibling risk ratios (lambda(s)), and odds ratios were calculated to assess familial aggregation of several different clinical manifestations.

RESULTS

The most common onset type among the 164 nontwin ASPs was pauciarticular (65% overall). Fifty-three percent of the ASPs were concordant for pauciarticular-onset JRA; 19% were concordant for a polyarticular disease onset. Among subjects with polyarticular-onset disease, significantly more joints were involved at onset in simplex patients than in ASPs (P = 0.008). The difference in age at JRA onset within sibpairs (sibling 1 versus sibling 2) was not significantly different. ASPs developed disease at a mean real-time difference of 5.1 years apart. Familial aggregation was found for tenosynovitis (lambda(s) 29.5), leukocytosis (lambda(s) 25), rheumatoid factor (lambda(s) 11.0), anemia (lambda(s) 1.7), and antinuclear antibodies (lambda(s) 1.3).

CONCLUSION

This study confirms the findings of earlier studies showing that a high proportion of ASPs overall show concordance of disease-onset type, except for the subset of patients with systemic disease, and that nontwin ASPs do not develop disease at the same point in real time. We conclude that JRA and its clinical manifestations do not differ substantially between ASPs and the simplex population. The exception is the number of affected joints at JRA onset among patients with polyarticular-onset disease. Familial aggregation of clinical features among ASPs adds strong evidence for a genetic background in this disease.

Increased prevalence of familial autoimmunity in simplex and multiplex families with juvenile rheumatoid arthritis

OBJECTIVE

To determine if the prevalence of autoimmunity among relatives of patients with juvenile rheumatoid arthritis (JRA) is greater than that among relatives of healthy volunteer control subjects.

METHODS

Interviews were used to obtain histories of the following disorders among living first- and second-degree relatives of 110 patients and 45 controls: alopecia areata, ankylosing spondylitis, dermatomyositis, Graves' disease, Hashimoto thyroiditis, insulin-dependent diabetes mellitus, inflammatory bowel disease, iritis, JRA, multiple sclerosis, psoriasis, RA, systemic lupus erythematosus, and vitiligo. Chi-squares, odds ratios (ORs), and 95% confidence intervals (95% CIs) were calculated. Families of 23 JRA affected sibpairs were interviewed subsequently.

RESULTS

There were no significant differences between patients and controls with regard to age, sex, ethnicity, or family size. Patients had 1,228 relatives and controls had 496 relatives. Of all the relatives of the patients, 155 had at least 1 autoimmune disorder, compared with 20 relatives of the controls (12.6% versus 4.0%; OR 3.4 [95% CI 2.1-5.7], P < 0.000001). The prevalence of autoimmunity was increased in first-degree and in second-degree relatives of patients (16.1% and 10.6%, respectively). The prevalence of Hashimoto thyroiditis was significantly higher in the relatives of patients (OR 3.5 [95% CI 1.6-7.9], P = 0.0008). The prevalences of other disorders were not significantly different. JRA affected sibpair families had an increased prevalence of autoimmunity (15.0%). A history of arthritis was found significantly more frequently in the JRA affected sibpair families, but not in the simplex families.

CONCLUSION

These data demonstrate that the prevalence of autoimmunity is significantly higher among first- and second-degree relatives of JRA patients. This suggests that clinically different autoimmune phenotypes may share common susceptibility genes, which may act as risk factors for autoimmunity.

Juvenile idiopathic arthritis genetics - what's new? What's next?

Studies have established the magnitude of the genetic basis of juvenile idiopathic arthritis (JIA). JIA is a complex genetic condition and the genes that influence susceptibility are actively being sought. A candidate gene approach is being used by several groups. MHC-, cytokine- and T-cell-related genes have all been positively associated with JIA. Here we review some of the latest genetic data, and discuss ways in which JIA genetic research might proceed.