The Genetics of Juvenile Idiopathic Arthritis: What Is New in 2010?

Study of NLRP3 Single Nucleotide Polymorphisms in Juvenile Systemic Lupus Erythematosus (JSLE)

Juvenile systemic lupus erythematosus (JSLE) is a multifaceted multifactorial disorder with an unclear etiopathogenesis. Environmental factors, genetic factors, and dysregulated and defective immune system responses are known to have a role in JSLE etiopathogenesis. NLRP3 inflammasome, as an important contributor to immune-mediated inflammatory responses, is assumed to be involved in JSLE etiopathogenesis. To determine whether the NLRP3 genetic variants are altered in patients with JSLE. Fifty-three patients diagnosed with JSLE and 56 healthy sex-matched controls were studied. NLRP3 (C/G rs10754558, C/T rs3806265, C/T rs4612666, A/C rs35829419) gene polymorphisms were evaluated using a TaqMan single-nucleotide polymorphism assay. C allele at position rs3806265 was detected in higher frequencies in patients than in the control group (37.74% vs 23.21%, P-value = .028). At the genotype level at the same position, CT has a significantly higher frequency in patients than the healthy subjects (75.47% vs 46.43%, P-value = .003). The NLRP3 rs3806265 CT genotype was detected at a higher frequency in patients with JSLE than in the healthy control group.

Validity and feasibility of the self-report EQ-5D-Y as a generic Health-Related Quality of Life outcome measure in children and adolescents with Juvenile Idiopathic Arthritis in Western Cape, South Africa

Background

Health-Related Quality of Life (HRQoL) data together with clinical findings allow for monitoring of intervention efficacy and the effect on HRQoL. Children with Juvenile Idiopathic Arthritis (JIA) experience symptoms often persisting into adulthood, emphasising the need to track HRQoL.

Objectives

The aim of this study was to investigate psychometric properties of the EuroQol five-dimensional youth questionnaire (EQ-5D-Y) in children with JIA.

Methods

A cross-sectional, analytical study design was used. Children 8 to 15 years were recruited, completing the self-report EQ-5D-Y and two other HRQoL questionnaires. Known group validity was established by comparing the effect size between children with different disease severities. Concurrent validity was tested using Kruskal–Wallis to compare the ranking of scores on different questionnaires. Feasibility was assessed by number of missing responses and time to complete each questionnaire.

Results

All questionnaires were able to distinguish between children with different JIA severity. There was a significant difference in ranking of most Juvenile Arthritis Multidimensional Assessment Report dimension scores across EQ-5D-Y levels, (p < 0.05), indicating concurrent validity. There was poor concurrent validity with the PedsQL dimensions tested with EQ-5D-Y, except for ‘pain’ (p = 0.001). The EQ-5D-Y was the quickest to complete with no missing values.

Conclusion

This study showed that the EQ-5D-Y is valid and feasible in measuring HRQoL in JIA children and adequately responsive to detect change over time.

Clinical implications

It is quick and easy to use in a busy clinical setting, allowing for effective JIA management monitoring.

Comorbidity of Type 1 Diabetes Mellitus in Patients with Juvenile Idiopathic Arthritis

OBJECTIVES

To determine the prevalence of type 1 diabetes mellitus (T1D) in patients with juvenile idiopathic arthritis (JIA) and to characterize patients having both.

STUDY DESIGN

Diabetes comorbidity was recorded in the National Pediatric Rheumatologic Database since 2012. Data from the North Rhine-Westphalian diabetes registry served as the reference population for the prevalence of diabetes in the general population. The National Pediatric Rheumatologic Database data were indirectly standardized for age and sex for comparison with the general population. The diabetes prevalence ratio was calculated using the Poisson regression model.

RESULTS

The analysis included 12 269 patients with JIA. A total of 58 patients had comorbid T1D, and the diabetes prevalence was 0.5%. The mean age was 11.6 years at the time of documentation, and the mean disease duration was 4.2 years. Compared with the general population, the prevalence of diabetes in patients with JIA was significantly increased (prevalence ratio 1.76 [95% CI 1.34; 2.28], P < .001). The onset of diabetes in patients with JIA was earlier than that reported in the reference data. Sixty-three percent of patients developed T1D before JIA. On average, diabetes onset was 56 months before the onset of JIA. Patients who first developed JIA developed T1D on average 40 months later. The majority of patients had not received disease-modifying antirheumatic drugs before diabetes onset.

CONCLUSIONS

T1D occurs more frequently in patients with JIA than in the general population. The likelihood of T1D occurrence appears to be slightly higher before JIA manifestation and without disease-modifying antirheumatic drug therapy after JIA onset.

An Update on Treatment of Pediatric Chronic Non-Infectious Uveitis

There are no standardized treatment protocols for pediatric non-infectious uveitis. Topical corticosteroids are the typical first-line agent, although systemic corticosteroids are used in intermediate, posterior and panuveitic uveitis. Corticosteroids are not considered to be long-term therapy due to potential ocular and systemic side effects. In children with severe and/or refractory uveitis, timely management with higher dose disease-modifying antirheumatic drugs (DMARDs) and biologic agents is important. Increased doses earlier in the disease course may lead to improved disease control and better visual outcomes. In general, methotrexate is the usual first-line steroid-sparing agent and given as a subcutaneous weekly injection at >0.5 mg/kg/dose or 10-15 mg/m2 due to better bioavailability. Other DMARDs, for instance mycophenolate, azathioprine, and cyclosporine are less common treatments for pediatric uveitis. Anti-tumor necrosis factor-alpha agents, primarily infliximab and adalimumab are used as second line agents in children refractory to methotrexate, or as first-line treatment in those with severe complicated disease at presentation. Infliximab may be given at a minimum of 7.5 mg/kg/dose every 4 weeks after loading doses, up to 20 mg/kg/dose. Adalimumab may be given up to 20 or 40 mg weekly. In children who fail anti-tumor necrosis factor-alpha agents, develop anti-tumor necrosis factor-alpha antibodies, experience adverse effects, or have difficulty with tolerance, there is less data available regarding subsequent treatment. Promising results have been noted with tocilizumab infusions every 2-4 weeks, abatacept monthly infusions and rituximab.

PADI4 and the HLA-DRB1 shared epitope in juvenile idiopathic arthritis

OBJECTIVE

Both genetic and environmental factors are associated with susceptibility to juvenile idiopathic arthritis (JIA). Many studies have reported that both a 'shared epitope' (SE) encoded by several HLA-DRB1 alleles and the peptidyl arginine deiminase type 4 (PADI4) gene polymorphisms are associated with susceptibility to rheumatoid arthritis (RA). However, it is uncertain whether JIA and RA share the latter genetic risk factor. Therefore, here we investigated relationships between HLA-SE and PADI4 polymorphisms with clinical subtypes of JIA.

METHODS

JIA patients (39 oligoarthritis, 48 RF-positive polyarthritis, 19 RF-negative polyarthritis and 82 systemic) and 188 healthy controls were genotyped for HLA-DRB1 by PCR-sequence-specific oligonucleotide probe methodology. Three PADI4 gene single nucleotide polymorphisms (SNPs), rs2240340, rs2240337 and rs1748033, were genotyped using TaqMan SNP Genotyping Assays.

RESULTS

Frequencies of the HLA-SE were higher in RF-positive polyarticular JIA than in healthy controls. RF-positive polyarticular JIA was associated with HLA-SE (OR = 5.3, 95% CI = 2.5-11.9, pc < 0.001). No associations were found between clinical subtypes of JIA and PADI4 allele frequency. Nonetheless, rs2240337 in the PADI4 gene was significantly associated with anti-cyclic citrullinated peptide antibody (ACPA)-positivity in JIA. The A allele at rs2240337 was a significant risk factor for ACPA positivity in JIA (OR = 5.6, 95% CI = 1.71-23.7 pc = 0.03).

CONCLUSION

PADI4 gene polymorphism is associated with ACPA-positivity in JIA. The association of HLA-SE with RF-positive polyarticular JIA as well as RA is confirmed in Japanese. Thus, HLA-SE and PADI4 status both influence JIA clinical manifestations.

Association of PTPN22 Gene Polymorphisms with Susceptibility to Juvenile Idiopathic Arthritis in Iranian Population

Juvenile idiopathic arthritis (JIA), the most common cause of chronic arthritis in children, is a complex immune-mediated disease with considerable long-term morbidity and mortality. According to previous studies, PTPN22 gene has been associated with JIA in several populations. In the present study, we attempted to determine the association of PTPN22 single nucleotide polymorphisms (SNPs) with susceptibility to JIA in Iranian population. Using the Real-time PCR allelic discrimination method, samples consisting of 55 unrelated patients and 93 healthy controls were genotyped. Using Fisher exact test or Chi-square test, genotypic and allelic frequencies were estimated. The results of our study indicated a significantly decreased association of rs1310182 (OR = 0.59, 95% CI = 0.36 -0.97, p = 0.037) with JIA. This association may indicate a protective role for rs1310182 SNP against JIA. More research would be needed to elucidate the mechanistic role of this association.

The safety of influenza vaccines in children: An Institute for Vaccine Safety white paper

Most influenza vaccines are generally safe, but influenza vaccines can cause rare serious adverse events. Some adverse events, such as fever and febrile seizures, are more common in children than adults. There can be differences in the safety of vaccines in different populations due to underlying differences in genetic predisposition to the adverse event. Live attenuated vaccines have not been studied adequately in children under 2 years of age to determine the risks of adverse events; more studies are needed to address this and several other priority safety issues with all influenza vaccines in children. All vaccines intended for use in children require safety testing in the target age group, especially in young children. Safety of one influenza vaccine in children should not be extrapolated to assumed safety of all influenza vaccines in children. The low rates of adverse events from influenza vaccines should not be a deterrent to the use of influenza vaccines because of the overwhelming evidence of the burden of disease due to influenza in children.

The biologic basis of clinical heterogeneity in juvenile idiopathic arthritis

Objective

Childhood arthritis encompasses a heterogeneous family of diseases. Significant variation in clinical presentation remains despite consensus-driven diagnostic classifications. Developments in data analysis provide powerful tools for interrogating large heterogeneous data sets. We report a novel approach to integrating biologic and clinical data toward a new classification for childhood arthritis, using computational biology for data-driven pattern recognition.

Methods

Probabilistic principal components analysis was used to transform a large set of data into 4 interpretable indicators or composite variables on which patients were grouped by cluster analysis. Sensitivity analysis was conducted to determine key variables in determining indicators and cluster assignment. Results were validated against an independent validation cohort.

Results

Meaningful biologic and clinical characteristics, including levels of proinflammatory cytokines and measures of disease activity, defined axes/indicators that identified homogeneous patient subgroups by cluster analysis. The new patient classifications resolved major differences between patient subpopulations better than International League of Associations for Rheumatology subtypes. Fourteen variables were identified by sensitivity analysis to crucially determine indicators and clusters. This new schema was conserved in an independent validation cohort.

Conclusion

Data-driven unsupervised machine learning is a powerful approach for interrogating clinical and biologic data toward disease classification, providing insight into the biology underlying clinical heterogeneity in childhood arthritis. Our analytical framework enabled the recovery of unique patterns from small cohorts and addresses a major challenge, patient numbers, in studying rare diseases.

Genetic variation in VTCN1 (B7-H4) is associated with course of disease in juvenile idiopathic arthritis

OBJECTIVE

The course of disease in juvenile idiopathic arthritis (JIA) is unpredictable with episodes of activity and remission. In order to identify predictive factors, 93 SNPs, JIA subtype, age at onset and ANA status were studied in relation to disease course.

METHODS

Genetic and clinical parameters were analysed in a cohort of 272 Caucasian patients with persistent oligoarthritis (n=129), extended oligoarthritis (n=57) and rheumatoid factor negative polyarthritis (n=86). Categories of disease course (remitting (n=65), intermediate (n=96) and unremitting (n=111)) were designed based on the cumulative time spent in active disease in the first 2 years.

RESULTS

Univariate analysis revealed association of the course of disease with JIA subtype (p=5.7*10(-5)) and three SNPs; VTCN1 rs10 923 223 (p=4.4*10(-5)), VTCN1 rs12 046 117 (p=0.017) and CDK6 rs42 041 (p=0.038). In a subsequent multivariate ordinal logistic regression analysis, VTCN1 rs10 923 223 (OR 0.41, 95%-CI 0.26 to 0.63) and JIA subtype (OR 3.8, 95%-CI 2.0 to 7.2; OR 2.5, 95%-CI 1.4 to 4.2, for extended oligoarthritis and RF-negative polyarthritis vs persistent oligoarthritis, respectively) were the strongest independent factors for course of disease.

CONCLUSIONS

This study provides evidence that VTCN1, encoding B7-H4, is associated with course of disease in selected subtypes of JIA. VTCN1 might be useful in predicting the course of disease.

Meta-analysis confirms association between TNFA-G238A variant and JIA, and between PTPN22-C1858T variant and oligoarticular, RF-polyarticular and RF-positive polyarticular JIA

BACKGROUND

Although more than 100 non-HLA variants have been tested for associations with juvenile idiopathic arthritis (JIA) in candidate gene studies, only a few have been replicated. We sought to replicate reported associations of single nucleotide polymorphisms (SNPs) in the PTPN22, TNFA and MIF genes in a well-characterized cohort of children with JIA.

METHODS

We genotyped and analyzed 4 SNPs in 3 genes: PTPN22 C1858T (rs2476601), TNFA G-308A, G-238A (rs1800629, rs361525) and MIF G-173C (rs755622) in 647 JIA cases and 751 healthy controls. We tested for association between each variant and JIA as well as JIA subtypes. We adjusted for multiple testing using permutation procedures. We also performed a meta-analysis that combined our results with published results from JIA association studies.

RESULTS

While the PTPN22 variant showed only modest association with JIA (OR = 1.29, p = 0.0309), it demonstrated a stronger association with the RF-positive polyarticular JIA subtype (OR = 2.12, p = 0.0041). The MIF variant was not associated with the JIA as a whole or with any subtype. The TNFA-238A variant was associated with JIA as a whole (OR 0.66, p = 0.0265), and demonstrated a stronger association with oligoarticular JIA (OR 0.33, p = 0.0006) that was significant after correction for multiple testing. TNFA-308A was not associated with JIA, but was nominally associated with systemic JIA (OR = 0.33, p = 0.0089) and enthesitis-related JIA (OR = 0.40, p = 0.0144). Meta-analyses confirmed significant associations between JIA and PTPN22 (OR 1.44, p <0.0001) and TNFA-238A (OR 0.69, p < 0.0086) variants. Subtype meta-analyses of the PTPN22 variant revealed associations between RF-positive, RF-negative, and oligoarticular JIA, that remained significant after multiple hypothesis correction (p < 0.0005, p = 0.0007, and p < 0.0005, respectively).

CONCLUSIONS

We have confirmed associations between JIA and PTPN22 and TNFA G-308A. By performing subtype analyses, we discovered a statistically-significant association between the TNFA-238A variant and oligoarticular JIA. Our meta-analyses confirm the associations between TNFA-238A and JIA, and show that PTPN22 C1858T is associated with JIA as well as with RF-positive, RF-negative and oligoarticular JIA.

CLARITY - ChiLdhood Arthritis Risk factor Identification sTudY

BACKGROUND

The aetiology of juvenile idiopathic arthritis (JIA) is largely unknown. We have established a JIA biobank in Melbourne, Australia called CLARITY - ChiLdhood Arthritis Risk factor Identification sTudY, with the broad aim of identifying genomic and environmental disease risk factors. We present here study protocols, and a comparison of socio-demographic, pregnancy, birth and early life characteristics of cases and controls collected over the first 3 years of the study.

METHODS

Cases are children aged ≤18 years with a diagnosis of JIA by 16 years. Controls are healthy children aged ≤18 years, born in the state of Victoria, undergoing a minor elective surgical procedure. Participant families provide clinical, epidemiological and environmental data via questionnaire, and a blood sample is collected.

RESULTS

Clinical characteristics of cases (n = 262) are similar to those previously reported. Demographically, cases were from families of higher socio-economic status. After taking this into account, the residual pregnancy and perinatal profiles of cases were similar to control children. No case-control differences in breastfeeding commencement or duration were detected, nor was there evidence of increased case exposure to tobacco smoke in utero. At interview, cases were less likely to be exposed to active parental smoking, but disease-related changes to parent behaviour may partly underlie this.

CONCLUSIONS

We show that, after taking into account socio-economic status, CLARITY cases and controls are well matched on basic epidemiological characteristics. CLARITY represents a new study platform with which to generate new knowledge as to the environmental and biological risk factors for JIA.

Simultaneous Juvenile Idiopathic Arthritis and Diabetes Mellitus Type 1 — A Finnish Nationwide Study

Objective.

To describe the occurrence and main clinical and laboratory findings of patients having both juvenile idiopathic arthritis (JIA) and diabetes mellitus type 1 (DM-1) in a period of 30 years.

Methods.

Eighty-two patients having simultaneous JIA and DM-1 were identified in the reimbursement registers of the Finnish National Institute of Insurance during the period 1976–2005. Data on their clinical histories were collected from patient files.

Results.

Occurrence of simultaneous JIA and DM-1 increased 4.5-fold between the first (1976-85) and the last (1996–2005) decade. Prevalence of uveitis was 7%, of rheumatoid factor seropositivity 15%; 22% of patients had a third autoimmune disease [autoimmune disease (AID)], and 16% had serious psychiatric problems.

Conclusion.

The occurrence of patients with the 2 diseases, JIA and DM-1, increased over 3 decades. The prevalence of uveitis was low, the number of seropositive patients was high, and further cases of AID were frequent. Patients had multiple additional problems necessitating multiprofessional care.