Juvenile Idiopathic Arthritis

MONDO:0011429 Pathograph 6 Show in embeddings browser

Juvenile idiopathic arthritis (JIA) is an umbrella term for the chronic arthritides of childhood beginning before 16 years of age and persisting for at least 6 weeks, after exclusion of infective, traumatic, malignant, and other defined causes. The International League of Associations for Rheumatology (ILAR) criteria stratify JIA into clinically distinct categories — oligoarticular, polyarticular rheumatoid-factor-negative, polyarticular rheumatoid-factor-positive, systemic, psoriatic, enthesitis-related, and undifferentiated — that differ in age of onset, joint pattern, extra-articular features, autoantibody status, and prognosis. The underlying mechanisms span a spectrum from predominantly autoimmune (oligo-/polyarticular, RF+ resembling adult rheumatoid arthritis) to predominantly autoinflammatory (systemic JIA, now recognised as part of the Still's disease continuum with adult-onset Still's disease). Long-term morbidity is driven by joint damage and deformity, chronic uveitis (notably in ANA-positive oligoarticular JIA), and — in systemic JIA — by macrophage activation syndrome. Management is risk-stratified and uses NSAIDs, intra-articular and systemic glucocorticoids, conventional DMARDs (methotrexate), and biologics targeting TNF, IL-1, or IL-6.

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4
Pathophys.
35
Phenotypes
6
Pathograph
2
Genes
4
Medical Actions
7
Subtypes
1
Deep Research
◆

Subtypes

7
Oligoarticular JIA MONDO:0019433
Up to four joints affected during the first six months. The most common JIA category in young children, with strong association with chronic anterior uveitis (particularly in ANA-positive girls). May extend to a polyarticular course.
Polyarticular JIA, RF-negative MONDO:0018456
Five or more joints affected in the first six months with negative rheumatoid factor. Symmetric or asymmetric involvement; clinically heterogeneous. Grounded to the broader polyarticular-JIA MONDO term; MONDO does not yet split RF-negative as a distinct identifier.
Polyarticular JIA, RF-positive MONDO:0018456
Five or more joints affected with persistent rheumatoid factor positivity on two tests at least three months apart. Immunogenetically most similar to adult rheumatoid arthritis; tends to be aggressive and erosive. Grounded to the broader polyarticular-JIA MONDO term; MONDO does not yet split RF-positive as a distinct identifier.
Systemic JIA (Still's disease)
Arthritis preceded or accompanied by quotidian fever, evanescent salmon-coloured rash, lymphadenopathy, hepatosplenomegaly, and serositis. Recognised as part of the Still's disease continuum with adult-onset Still's disease and complicated by macrophage activation syndrome. (No dedicated MONDO subtype term identified by exact-label lookup; left ungrounded until verified.)
Psoriatic JIA
Arthritis with psoriasis, or arthritis plus at least two of: dactylitis, nail pitting / onycholysis, or psoriasis in a first-degree relative. (No dedicated MONDO subtype term identified by exact-label lookup; left ungrounded until verified.)
Enthesitis-Related JIA MONDO:0019437
Arthritis and/or enthesitis with associated features (HLA-B27, sacroiliitis, acute anterior uveitis, or family history of spondyloarthropathy). Predominantly affects older boys; overlaps with juvenile-onset spondyloarthritis.
Undifferentiated
JIA that does not fulfil criteria for any of the above categories or fulfils criteria for more than one. A residual ILAR category.
⚙

Pathophysiology

4
Synovial Leukocyte Infiltration
T-cell and macrophage recruitment to the synovial membrane is the initiating cellular event of synovitis in JIA, with the relative contribution of adaptive autoimmunity versus innate autoinflammation varying by ILAR subtype. Recent synovial atlas and spatial transcriptomic studies have identified that these infiltrating immune cells form organized inflammatory niches within the synovium, with distinct subsets of T cells (particularly lymphocyte activation markers), synovial macrophages, and B cells positioning themselves in tissue-specific configurations that sustain chronic arthritis. The genetic susceptibility loci identified by GWAS (lymphocyte activation, cytokine signaling, and immune regulation genes) directly correlate with these immune-cell states, linking inherited risk to the cellular environment perpetuating synovitis.
T cell CL:0000084 macrophage CL:0000235 B cell CL:0000236
immune response GO:0006955 ⚠ ABNORMAL lymphocyte activation GO:0046649 ↑ INCREASED
synovial membrane UBERON:0002018
Downstream
Synovial Hyperplasia
Cytokine-Mediated Articular Damage
Show evidence (1 reference)
PMID:42266057 SUPPORT Human Clinical
"Synovial atlas and spatial transcriptomic studies have further connected genetic susceptibility to immune-cell states and organized inflammatory niches, linking inherited risk to the chronic arthritis-sustaining tissue environment."
Synovial atlas studies demonstrate that genetic susceptibility loci are reflected in specific immune-cell states and organized inflammatory niches within the synovium that sustain chronic arthritis in JIA.
Synovial Hyperplasia
Activated synovial fibroblasts and resident synoviocytes proliferate under cytokine drive, producing the thickened, vascularised synovium (pannus-like membrane in long-standing disease) that supports ongoing inflammation and joint damage.
synovial cell CL:0000214
synovial membrane UBERON:0002018
Downstream
Cytokine-Mediated Articular Damage
Cytokine-Mediated Articular Damage
Pro-inflammatory cytokine production (notably TNF, IL-1, IL-6) by infiltrating leukocytes and hyperplastic synovium drives cartilage and bone destruction at the joint, the proximate mechanism of the long-term joint-damage phenotype across non-systemic JIA categories.
cytokine production GO:0001816 ↑ INCREASED
synovial membrane UBERON:0002018
Downstream
Arthritis
Systemic Autoinflammation (sJIA)
Systemic JIA is dominated by innate-immune activation with prominent IL-1 and IL-6 signalling, distinguishing it pathophysiologically from the more T-cell-driven oligo-/polyarticular categories. Under current consensus it is considered the same entity as adult-onset Still's disease.
interleukin-1 mediated signaling pathway GO:0070498 ↑ INCREASED interleukin-6 mediated signaling pathway GO:0070102 ↑ INCREASED
Downstream
Fever
Show evidence (2 references)
PMID:38756937 SUPPORT Human Clinical
"sJIA and AOSD are rare autoinflammatory disorders that have similar pathophysiological and clinical features."
Directly supports systemic JIA as an autoinflammatory disorder sharing pathophysiology with adult-onset Still's disease.
PMID:39317417 SUPPORT Human Clinical
"Systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD) are considered the same disease, but a common approach for diagnosis and management is still missing."
Supports the consensus position that systemic JIA and adult-onset Still's disease are the same disease (the Still's disease continuum).
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Juvenile Idiopathic Arthritis Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

35
Cardiovascular 3
Lymphadenopathy FREQUENT Lymphadenopathy HP:0002716
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0002716 | Lymphadenopathy | Frequent (79-30%)"
Orphanet records lymphadenopathy as a frequent (30-79%) phenotype of systemic-onset juvenile idiopathic arthritis.
Pericarditis OCCASIONAL Pericarditis HP:0001701
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0001701 | Pericarditis | Occasional (29-5%)"
Orphanet records pericarditis as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis.
Splenomegaly OCCASIONAL Splenomegaly HP:0001744
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0001744 | Splenomegaly | Occasional (29-5%)"
Orphanet records splenomegaly as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis.
Eye 2
Uveitis FREQUENT Uveitis HP:0000554
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0000554 | Uveitis | Frequent (79-30%)"
Orphanet records uveitis as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis.
Visual loss OCCASIONAL Visual loss HP:0000572
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0000572 | Visual loss | Occasional (29-5%)"
Orphanet records visual loss as an occasional (5-29%) phenotype of oligoarticular juvenile idiopathic arthritis.
Immune 2
Skin rash VERY_FREQUENT Skin rash HP:0000988
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0000988 | Skin rash | Very frequent (99-80%)"
Orphanet records skin rash as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis.
Autoimmunity VERY_FREQUENT Autoimmunity HP:0002960
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0002960 | Autoimmunity | Very frequent (99-80%)"
Orphanet records autoimmunity as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis.
Metabolism 2
Joint Swelling VERY_FREQUENT Joint swelling HP:0001386
Fever VERY_FREQUENT Fever HP:0001945
Musculoskeletal 7
Arthritis VERY_FREQUENT Arthritis HP:0001369
Show evidence (1 reference)
PMID:29037901 SUPPORT Human Clinical
"Juvenile Idiopathic Arthritis (JIA) is characterized with a variable pattern of articular involvement and systemic symptoms"
Supports articular involvement (arthritis) as a defining clinical feature of JIA.
Joint Stiffness VERY_FREQUENT Joint stiffness HP:0001387
Joint Deformity FREQUENT Limitation of joint mobility HP:0001376
Show evidence (1 reference)
PMID:29848426 SUPPORT Human Clinical
"Most common joints involved were hand (50%), wrist (50%), and knee (35.7%)."
Cross-sectional ILAR-defined JIA cohort directly supports hand, wrist, and knee as the joints most commonly affected by deformity in JIA.
Osteopenia OCCASIONAL Osteopenia HP:0000938
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0000938 | Osteopenia | Occasional (29-5%)"
Orphanet records osteopenia as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis.
Joint hypermobility FREQUENT Joint hypermobility HP:0001382
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0001382 | Joint hypermobility | Frequent (79-30%)"
Orphanet records joint hypermobility as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis.
Symetrical distal arthritis FREQUENT Symmetric polyarthritis HP:0040311
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0040311 | Symetrical distal arthritis | Frequent (79-30%)"
Orphanet records symetrical distal arthritis as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Reduced bone mineral density OCCASIONAL Reduced bone mineral density HP:0004349
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0004349 | Reduced bone mineral density | Occasional (29-5%)"
Orphanet records reduced bone mineral density as an occasional (5-29%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Constitutional 2
Arthralgia VERY_FREQUENT Arthralgia HP:0002829
Abdominal pain OCCASIONAL Abdominal pain HP:0002027
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0002027 | Abdominal pain | Occasional (29-5%)"
Orphanet records abdominal pain as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis.
Growth 2
Growth delay OCCASIONAL Growth delay HP:0001510
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0001510 | Growth delay | Occasional (29-5%)"
Orphanet records growth delay as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis.
Failure to thrive FREQUENT Failure to thrive HP:0001508
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0001508 | Failure to thrive | Frequent (79-30%)"
Orphanet records failure to thrive as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis.
Other 15
Chronic Anterior Uveitis FREQUENT Anterior uveitis HP:0012122
Temporal: CHRONIC
Elevated erythrocyte sedimentation rate VERY_FREQUENT Elevated erythrocyte sedimentation rate HP:0003565
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0003565 | Elevated erythrocyte sedimentation rate | Very frequent (99-80%)"
Orphanet records elevated erythrocyte sedimentation rate as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis.
Juvenile rheumatoid arthritis VERY_FREQUENT Juvenile rheumatoid arthritis HP:0005681
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0005681 | Juvenile rheumatoid arthritis | Very frequent (99-80%)"
Orphanet records juvenile rheumatoid arthritis as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis.
Elevated circulating C-reactive protein concentration VERY_FREQUENT Elevated circulating C-reactive protein concentration HP:0011227
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0011227 | Elevated circulating C-reactive protein concentration | Very frequent (99-80%)"
Orphanet records elevated circulating C-reactive protein concentration as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis.
Glomerulonephritis OCCASIONAL Glomerulonephritis HP:0000099
Show evidence (1 reference)
ORPHA:85414 SUPPORT Other
"HP:0000099 | Glomerulonephritis | Occasional (29-5%)"
Orphanet records glomerulonephritis as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis.
Antinuclear antibody positivity VERY_FREQUENT Antinuclear antibody positivity HP:0003493
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0003493 | Antinuclear antibody positivity | Very frequent (99-80%)"
Orphanet records antinuclear antibody positivity as a very frequent (80-99%) phenotype of oligoarticular juvenile idiopathic arthritis.
Oligoarthritis VERY_FREQUENT Oligoarthritis HP:0040313
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0040313 | Oligoarthritis | Very frequent (99-80%)"
Orphanet records oligoarthritis as a very frequent (80-99%) phenotype of oligoarticular juvenile idiopathic arthritis.
Knee osteoarthritis FREQUENT Knee osteoarthritis HP:0005086
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0005086 | Knee osteoarthritis | Frequent (79-30%)"
Orphanet records knee osteoarthritis as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis.
Increased serum interferon-gamma level FREQUENT Increased circulating interferon-gamma concentration HP:0030356
Show evidence (1 reference)
ORPHA:85410 SUPPORT Other
"HP:0030356 | Increased serum interferon-gamma level | Frequent (79-30%)"
Orphanet records increased serum interferon-gamma level as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis.
Rheumatoid factor positive VERY_FREQUENT Rheumatoid factor positive HP:0002923
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0002923 | Rheumatoid factor positive | Very frequent (99-80%)"
Orphanet records rheumatoid factor positive as a very frequent (80-99%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Polyarticular arthritis VERY_FREQUENT Polyarticular arthritis HP:0005764
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0005764 | Polyarticular arthritis | Very frequent (99-80%)"
Orphanet records polyarticular arthritis as a very frequent (80-99%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Progressive joint destruction FREQUENT Progressive joint destruction HP:0005187
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0005187 | Progressive joint destruction | Frequent (79-30%)"
Orphanet records progressive joint destruction as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Interphalangeal joint erosions FREQUENT Interphalangeal joint erosions HP:0006252
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0006252 | Interphalangeal joint erosions | Frequent (79-30%)"
Orphanet records interphalangeal joint erosions as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Synovitis FREQUENT Synovitis HP:0100769
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0100769 | Synovitis | Frequent (79-30%)"
Orphanet records synovitis as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
Premature epimetaphyseal fusion OCCASIONAL Premature epimetaphyseal fusion HP:0010588
Show evidence (1 reference)
ORPHA:85435 SUPPORT Other
"HP:0010588 | Premature epimetaphyseal fusion | Occasional (29-5%)"
Orphanet records premature epimetaphyseal fusion as an occasional (5-29%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis.
🧬

Genetic Associations

2
HLA-DRB1 (Susceptibility)
Gene: HLA-DRB1 hgnc:4948
Show evidence (4 references)
PMID:29037901 SUPPORT Human Clinical
"Genetic predisposition to JIA is mainly due to HLA class II molecules (HLA-DRB1, HLA-DPB1), although HLA class I molecules and non-HLA genes have been implicated, too."
Meta-analysis directly supports HLA-DRB1 as a primary genetic susceptibility locus for JIA.
PMID:29037901 SUPPORT Human Clinical
"HLA-DRB1*08 is a strong factor predisposing to JIA, both for oligo-articular and poly-articular forms"
Meta-analysis directly supports HLA-DRB1*08 as a predisposing allele for both oligoarticular and polyarticular JIA.
PMID:29037901 SUPPORT Human Clinical
"iii) HLA-DRB1*11"
Meta-analysis confirms HLA-DRB1*11 as an additional predisposing allele for oligoarticular JIA.
+ 1 more reference
Non-HLA immune-susceptibility genes (lymphocyte activation, cytokine signaling, immune regulation) (Susceptibility)
Show evidence (3 references)
PMID:42266057 SUPPORT Human Clinical
"Classical HLA and non-HLA studies established the polygenic immune-mediated pathogenesis of JIA with distinct, partially overlapping, genetic architectures across the International League of Associations for Rheumatology categories."
Recent review establishes polygenic immune-mediated pathogenesis of JIA with distinct genetic architectures across ILAR categories.
PMID:42266057 SUPPORT Human Clinical
"Recent subtype-integrative genome-wide association studies and transcriptomic and chromatin-interaction analyses prioritized candidate genes mediating lymphocyte activation, cytokine signaling, and immune regulation."
GWAS and transcriptomic studies identify candidate genes for lymphocyte activation, cytokine signaling, and immune regulation in polyarticular JIA pathogenesis.
PMID:42266057 SUPPORT Human Clinical
"Synovial atlas and spatial transcriptomic studies have further connected genetic susceptibility to immune-cell states and organized inflammatory niches, linking inherited risk to the chronic arthritis-sustaining tissue environment."
Synovial atlas studies link genetic susceptibility loci to specific immune-cell states and inflammatory tissue niches in polyarticular JIA.
💊

Medical Actions

4
NSAIDs
Action: NSAID therapy MAXO:0000221
Non-steroidal anti-inflammatory drugs are first-line symptom control for active arthritis and a useful diagnostic/therapeutic trial in early disease.
Intra-articular and Systemic Glucocorticoids
Action: glucocorticoid therapy Ontology label: Pharmacotherapy NCIT:C15986
Agent: triamcinolone CHEBI:9667
Intra-articular steroid injection (most often triamcinolone) is standard for oligoarticular JIA. Short-course systemic glucocorticoids are used as a bridge to DMARDs and as front-line therapy in active systemic JIA.
Methotrexate (conventional DMARD)
Action: methotrexate therapy Ontology label: Pharmacotherapy NCIT:C15986
Agent: methotrexate CHEBI:44185
Methotrexate is the conventional synthetic DMARD of first choice for polyarticular and extended-oligoarticular JIA, slowing radiographic progression and inducing remission.
TNF, IL-1, and IL-6 Inhibitor Biologics
Action: biologic DMARD therapy Ontology label: Pharmacotherapy NCIT:C15986
Agent: etanercept NCIT:C2381 adalimumab NCIT:C65216 anakinra NCIT:C38717 canakinumab NCIT:C80971 tocilizumab NCIT:C84217
Biologic DMARDs targeting TNF (etanercept, adalimumab), IL-1 (anakinra, canakinumab), and IL-6 (tocilizumab) are central to treatment of JIA refractory to methotrexate. In systemic JIA, IL-1 and IL-6 inhibitors are increasingly used as early therapy alongside short-course glucocorticoids.
Show evidence (2 references)
PMID:39317417 SUPPORT Human Clinical
"The optimal therapeutic strategy relies on early use of interleukin (IL-1 or IL-6 inhibitors associated to short duration glucocorticoid (GC)."
EULAR/PReS recommendations directly support early IL-1 or IL-6 inhibitor therapy plus short-course glucocorticoids for systemic JIA / Still's disease.
PMID:38756937 SUPPORT Human Clinical
"Recently, targeted therapies such as interleukin (IL)-1 and IL-6 inhibitors have become available for the treatment of sJIA and AOSD."
Supports availability of IL-1 and IL-6 inhibitor biologics for systemic JIA.
{ }

Source YAML

click to show 
name: Juvenile Idiopathic Arthritis
creation_date: '2026-05-12T00:00:00Z'
updated_date: '2026-05-12T21:00:00Z'
description: >-
  Juvenile idiopathic arthritis (JIA) is an umbrella term for the chronic
  arthritides of childhood beginning before 16 years of age and persisting for
  at least 6 weeks, after exclusion of infective, traumatic, malignant, and
  other defined causes. The International League of Associations for
  Rheumatology (ILAR) criteria stratify JIA into clinically distinct
  categories — oligoarticular, polyarticular rheumatoid-factor-negative,
  polyarticular rheumatoid-factor-positive, systemic, psoriatic,
  enthesitis-related, and undifferentiated — that differ in age of onset, joint
  pattern, extra-articular features, autoantibody status, and prognosis. The
  underlying mechanisms span a spectrum from predominantly autoimmune
  (oligo-/polyarticular, RF+ resembling adult rheumatoid arthritis) to
  predominantly autoinflammatory (systemic JIA, now recognised as part of the
  Still's disease continuum with adult-onset Still's disease). Long-term
  morbidity is driven by joint damage and deformity, chronic uveitis (notably
  in ANA-positive oligoarticular JIA), and — in systemic JIA — by macrophage
  activation syndrome. Management is risk-stratified and uses NSAIDs,
  intra-articular and systemic glucocorticoids, conventional DMARDs
  (methotrexate), and biologics targeting TNF, IL-1, or IL-6.
categories:
- Pediatric Rheumatologic Disease
- Autoimmune Disease
- Autoinflammatory Disease
- Chronic Arthritis
has_subtypes:
- name: Oligoarticular
  display_name: Oligoarticular JIA
  subtype_term:
    preferred_term: oligoarticular juvenile idiopathic arthritis
    term:
      id: MONDO:0019433
      label: oligoarticular juvenile idiopathic arthritis
  description: >-
    Up to four joints affected during the first six months. The most common
    JIA category in young children, with strong association with chronic
    anterior uveitis (particularly in ANA-positive girls). May extend to a
    polyarticular course.
- name: Polyarticular RF-negative
  display_name: Polyarticular JIA, RF-negative
  subtype_term:
    preferred_term: polyarticular juvenile idiopathic arthritis
    term:
      id: MONDO:0018456
      label: polyarticular juvenile idiopathic arthritis
  description: >-
    Five or more joints affected in the first six months with negative
    rheumatoid factor. Symmetric or asymmetric involvement; clinically
    heterogeneous. Grounded to the broader polyarticular-JIA MONDO term;
    MONDO does not yet split RF-negative as a distinct identifier.
- name: Polyarticular RF-positive
  display_name: Polyarticular JIA, RF-positive
  subtype_term:
    preferred_term: polyarticular juvenile idiopathic arthritis
    term:
      id: MONDO:0018456
      label: polyarticular juvenile idiopathic arthritis
  description: >-
    Five or more joints affected with persistent rheumatoid factor
    positivity on two tests at least three months apart. Immunogenetically
    most similar to adult rheumatoid arthritis; tends to be aggressive and
    erosive. Grounded to the broader polyarticular-JIA MONDO term; MONDO
    does not yet split RF-positive as a distinct identifier.
- name: Systemic
  display_name: Systemic JIA (Still's disease)
  description: >-
    Arthritis preceded or accompanied by quotidian fever, evanescent
    salmon-coloured rash, lymphadenopathy, hepatosplenomegaly, and
    serositis. Recognised as part of the Still's disease continuum with
    adult-onset Still's disease and complicated by macrophage activation
    syndrome. (No dedicated MONDO subtype term identified by exact-label
    lookup; left ungrounded until verified.)
- name: Psoriatic
  display_name: Psoriatic JIA
  description: >-
    Arthritis with psoriasis, or arthritis plus at least two of: dactylitis,
    nail pitting / onycholysis, or psoriasis in a first-degree relative.
    (No dedicated MONDO subtype term identified by exact-label lookup;
    left ungrounded until verified.)
- name: Enthesitis-related
  display_name: Enthesitis-Related JIA
  subtype_term:
    preferred_term: enthesitis-related juvenile idiopathic arthritis
    term:
      id: MONDO:0019437
      label: enthesitis-related juvenile idiopathic arthritis
  description: >-
    Arthritis and/or enthesitis with associated features (HLA-B27,
    sacroiliitis, acute anterior uveitis, or family history of
    spondyloarthropathy). Predominantly affects older boys; overlaps with
    juvenile-onset spondyloarthritis.
- name: Undifferentiated
  description: >-
    JIA that does not fulfil criteria for any of the above categories or
    fulfils criteria for more than one. A residual ILAR category.
pathophysiology:
- name: Synovial Leukocyte Infiltration
  description: >-
    T-cell and macrophage recruitment to the synovial membrane is the
    initiating cellular event of synovitis in JIA, with the relative
    contribution of adaptive autoimmunity versus innate autoinflammation
    varying by ILAR subtype. Recent synovial atlas and spatial transcriptomic
    studies have identified that these infiltrating immune cells form
    organized inflammatory niches within the synovium, with distinct subsets
    of T cells (particularly lymphocyte activation markers), synovial
    macrophages, and B cells positioning themselves in tissue-specific
    configurations that sustain chronic arthritis. The genetic susceptibility
    loci identified by GWAS (lymphocyte activation, cytokine signaling, and
    immune regulation genes) directly correlate with these immune-cell states,
    linking inherited risk to the cellular environment perpetuating synovitis.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: B cell
    term:
      id: CL:0000236
      label: B cell
  biological_processes:
  - preferred_term: immune response
    modifier: ABNORMAL
    term:
      id: GO:0006955
      label: immune response
  - preferred_term: lymphocyte activation
    modifier: INCREASED
    term:
      id: GO:0046649
      label: lymphocyte activation
  locations:
  - preferred_term: synovial membrane
    term:
      id: UBERON:0002018
      label: synovial membrane of synovial joint
  downstream:
  - target: Synovial Hyperplasia
    causal_link_type: DIRECT
  - target: Cytokine-Mediated Articular Damage
    causal_link_type: DIRECT
  evidence:
  - reference: PMID:42266057
    reference_title: "Polyarticular juvenile idiopathic arthritis: insights from genetic studies on disease risk and pathogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Synovial atlas and spatial transcriptomic studies have further connected genetic susceptibility to immune-cell states and organized inflammatory niches, linking inherited risk to the chronic arthritis-sustaining tissue environment."
    explanation: Synovial atlas studies demonstrate that genetic susceptibility loci are reflected in specific immune-cell states and organized inflammatory niches within the synovium that sustain chronic arthritis in JIA.
- name: Synovial Hyperplasia
  description: >-
    Activated synovial fibroblasts and resident synoviocytes proliferate
    under cytokine drive, producing the thickened, vascularised synovium
    (pannus-like membrane in long-standing disease) that supports
    ongoing inflammation and joint damage.
  cell_types:
  - preferred_term: synovial cell
    term:
      id: CL:0000214
      label: synovial cell
  locations:
  - preferred_term: synovial membrane
    term:
      id: UBERON:0002018
      label: synovial membrane of synovial joint
  downstream:
  - target: Cytokine-Mediated Articular Damage
    causal_link_type: DIRECT
- name: Cytokine-Mediated Articular Damage
  description: >-
    Pro-inflammatory cytokine production (notably TNF, IL-1, IL-6) by
    infiltrating leukocytes and hyperplastic synovium drives cartilage
    and bone destruction at the joint, the proximate mechanism of the
    long-term joint-damage phenotype across non-systemic JIA categories.
  biological_processes:
  - preferred_term: cytokine production
    modifier: INCREASED
    term:
      id: GO:0001816
      label: cytokine production
  locations:
  - preferred_term: synovial membrane
    term:
      id: UBERON:0002018
      label: synovial membrane of synovial joint
  downstream:
  - target: Arthritis
    causal_link_type: DIRECT
- name: Systemic Autoinflammation (sJIA)
  description: >-
    Systemic JIA is dominated by innate-immune activation with prominent
    IL-1 and IL-6 signalling, distinguishing it pathophysiologically from
    the more T-cell-driven oligo-/polyarticular categories. Under current
    consensus it is considered the same entity as adult-onset Still's
    disease.
  evidence:
  - reference: PMID:38756937
    reference_title: "Diagnosing and Treating Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease as Part of the Still's Disease Continuum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "sJIA and AOSD are rare autoinflammatory disorders that have similar pathophysiological and clinical features."
    explanation: Directly supports systemic JIA as an autoinflammatory disorder sharing pathophysiology with adult-onset Still's disease.
  - reference: PMID:39317417
    reference_title: "EULAR/PReS recommendations for the diagnosis and management of Still's disease, comprising systemic juvenile idiopathic arthritis and adult-onset Still's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD) are considered the same disease, but a common approach for diagnosis and management is still missing."
    explanation: Supports the consensus position that systemic JIA and adult-onset Still's disease are the same disease (the Still's disease continuum).
  biological_processes:
  - preferred_term: interleukin-1 mediated signaling pathway
    modifier: INCREASED
    term:
      id: GO:0070498
      label: interleukin-1-mediated signaling pathway
  - preferred_term: interleukin-6 mediated signaling pathway
    modifier: INCREASED
    term:
      id: GO:0070102
      label: interleukin-6-mediated signaling pathway
  downstream:
  - target: Fever
    causal_link_type: DIRECT
phenotypes:
- category: Musculoskeletal
  name: Arthritis
  frequency: VERY_FREQUENT
  description: >-
    Chronic arthritis of one or more joints lasting at least six weeks is
    the defining feature across all ILAR JIA categories.
  phenotype_term:
    preferred_term: Arthritis
    term:
      id: HP:0001369
      label: Arthritis
  evidence:
  - reference: PMID:29037901
    reference_title: "HLA-DRB1 alleles and juvenile idiopathic arthritis: Diagnostic clues emerging from a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Juvenile Idiopathic Arthritis (JIA) is characterized with a variable pattern of articular involvement and systemic symptoms"
    explanation: Supports articular involvement (arthritis) as a defining clinical feature of JIA.
- category: Musculoskeletal
  name: Joint Swelling
  frequency: VERY_FREQUENT
  description: >-
    Swelling and warmth of affected joints from synovial inflammation and
    effusion. Often the presenting sign in oligo-/polyarticular JIA.
  phenotype_term:
    preferred_term: Joint swelling
    term:
      id: HP:0001386
      label: Joint swelling
- category: Musculoskeletal
  name: Joint Stiffness
  frequency: VERY_FREQUENT
  description: >-
    Morning and post-rest stiffness that improves with activity; a
    characteristic feature of chronic inflammatory arthritis in children.
  phenotype_term:
    preferred_term: Joint stiffness
    term:
      id: HP:0001387
      label: Joint stiffness
- category: Musculoskeletal
  name: Arthralgia
  frequency: VERY_FREQUENT
  description: >-
    Joint pain, often disproportionate to apparent swelling in younger
    children where pain may present as reluctance to bear weight, limp, or
    behavioural change rather than verbalised complaint.
  phenotype_term:
    preferred_term: Arthralgia
    term:
      id: HP:0002829
      label: Arthralgia
- category: Musculoskeletal
  name: Joint Deformity
  frequency: FREQUENT
  description: >-
    Long-standing or inadequately treated disease leads to fixed joint
    deformities, most commonly involving hands, wrists, and knees, with
    higher risk in polyarticular and RF-seropositive subsets.
  phenotype_term:
    preferred_term: Joint deformity
    term:
      id: HP:0001376
      label: Limitation of joint mobility
  evidence:
  - reference: PMID:29848426
    reference_title: "Spectrum of Joint Deformities in Children with Juvenile Idiopathic Arthritis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most common joints involved were hand (50%), wrist (50%), and knee (35.7%)."
    explanation: Cross-sectional ILAR-defined JIA cohort directly supports hand, wrist, and knee as the joints most commonly affected by deformity in JIA.
- category: Constitutional
  name: Fever
  subtype: Systemic
  frequency: VERY_FREQUENT
  description: >-
    Quotidian or quotidian-like fever is a defining feature of systemic
    JIA (Still's disease) and uncommon in the non-systemic categories;
    qualified here to the Systemic subtype.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
- category: Ophthalmologic
  name: Chronic Anterior Uveitis
  subtype: Oligoarticular
  frequency: FREQUENT
  description: >-
    Chronic, often asymptomatic anterior uveitis is the major
    extra-articular complication of oligoarticular JIA, particularly in
    ANA-positive young girls, and a leading cause of visual morbidity
    if not detected by routine slit-lamp screening. Acute symptomatic
    anterior uveitis also occurs in enthesitis-related JIA. Subtype-
    qualified here to oligoarticular JIA, the highest-risk category.
  phenotype_term:
    preferred_term: Anterior uveitis
    term:
      id: HP:0012122
      label: Anterior uveitis
    temporality: CHRONIC
- name: "Skin rash"
  category: Dermatologic
  subtype: Systemic
  frequency: VERY_FREQUENT
  description: "Skin rash is reported as a very frequent (80-99%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Skin rash"
    term:
      id: HP:0000988
      label: "Skin rash"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000988 | Skin rash | Very frequent (99-80%)"
    explanation: "Orphanet records skin rash as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Autoimmunity"
  category: Immunologic
  subtype: Systemic
  frequency: VERY_FREQUENT
  description: "Autoimmunity is reported as a very frequent (80-99%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Autoimmunity"
    term:
      id: HP:0002960
      label: "Autoimmunity"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002960 | Autoimmunity | Very frequent (99-80%)"
    explanation: "Orphanet records autoimmunity as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Elevated erythrocyte sedimentation rate"
  category: Laboratory
  subtype: Systemic
  frequency: VERY_FREQUENT
  description: "Elevated erythrocyte sedimentation rate is reported as a very frequent (80-99%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Elevated erythrocyte sedimentation rate"
    term:
      id: HP:0003565
      label: "Elevated erythrocyte sedimentation rate"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003565 | Elevated erythrocyte sedimentation rate | Very frequent (99-80%)"
    explanation: "Orphanet records elevated erythrocyte sedimentation rate as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Juvenile rheumatoid arthritis"
  category: Musculoskeletal
  subtype: Systemic
  frequency: VERY_FREQUENT
  description: "Juvenile rheumatoid arthritis is reported as a very frequent (80-99%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Juvenile rheumatoid arthritis"
    term:
      id: HP:0005681
      label: "Juvenile rheumatoid arthritis"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0005681 | Juvenile rheumatoid arthritis | Very frequent (99-80%)"
    explanation: "Orphanet records juvenile rheumatoid arthritis as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Elevated circulating C-reactive protein concentration"
  category: Laboratory
  subtype: Systemic
  frequency: VERY_FREQUENT
  description: "Elevated circulating C-reactive protein concentration is reported as a very frequent (80-99%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Elevated circulating C-reactive protein concentration"
    term:
      id: HP:0011227
      label: "Elevated circulating C-reactive protein concentration"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0011227 | Elevated circulating C-reactive protein concentration | Very frequent (99-80%)"
    explanation: "Orphanet records elevated circulating C-reactive protein concentration as a very frequent (80-99%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Lymphadenopathy"
  category: Hematologic
  subtype: Systemic
  frequency: FREQUENT
  description: "Lymphadenopathy is reported as a frequent (30-79%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Lymphadenopathy"
    term:
      id: HP:0002716
      label: "Lymphadenopathy"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002716 | Lymphadenopathy | Frequent (79-30%)"
    explanation: "Orphanet records lymphadenopathy as a frequent (30-79%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Glomerulonephritis"
  category: Renal
  subtype: Systemic
  frequency: OCCASIONAL
  description: "Glomerulonephritis is reported as an occasional (5-29%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Glomerulonephritis"
    term:
      id: HP:0000099
      label: "Glomerulonephritis"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000099 | Glomerulonephritis | Occasional (29-5%)"
    explanation: "Orphanet records glomerulonephritis as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Osteopenia"
  category: Musculoskeletal
  subtype: Systemic
  frequency: OCCASIONAL
  description: "Osteopenia is reported as an occasional (5-29%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Osteopenia"
    term:
      id: HP:0000938
      label: "Osteopenia"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000938 | Osteopenia | Occasional (29-5%)"
    explanation: "Orphanet records osteopenia as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Growth delay"
  category: Growth
  subtype: Systemic
  frequency: OCCASIONAL
  description: "Growth delay is reported as an occasional (5-29%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Growth delay"
    term:
      id: HP:0001510
      label: "Growth delay"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001510 | Growth delay | Occasional (29-5%)"
    explanation: "Orphanet records growth delay as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Pericarditis"
  category: Cardiovascular
  subtype: Systemic
  frequency: OCCASIONAL
  description: "Pericarditis is reported as an occasional (5-29%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Pericarditis"
    term:
      id: HP:0001701
      label: "Pericarditis"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001701 | Pericarditis | Occasional (29-5%)"
    explanation: "Orphanet records pericarditis as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Splenomegaly"
  category: Hematologic
  subtype: Systemic
  frequency: OCCASIONAL
  description: "Splenomegaly is reported as an occasional (5-29%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Splenomegaly"
    term:
      id: HP:0001744
      label: "Splenomegaly"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001744 | Splenomegaly | Occasional (29-5%)"
    explanation: "Orphanet records splenomegaly as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Abdominal pain"
  category: Gastrointestinal
  subtype: Systemic
  frequency: OCCASIONAL
  description: "Abdominal pain is reported as an occasional (5-29%) manifestation of systemic-onset juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Abdominal pain"
    term:
      id: HP:0002027
      label: "Abdominal pain"
  evidence:
  - reference: ORPHA:85414
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002027 | Abdominal pain | Occasional (29-5%)"
    explanation: "Orphanet records abdominal pain as an occasional (5-29%) phenotype of systemic-onset juvenile idiopathic arthritis."
- name: "Antinuclear antibody positivity"
  category: Immunologic
  subtype: Oligoarticular
  frequency: VERY_FREQUENT
  description: "Antinuclear antibody positivity is reported as a very frequent (80-99%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Antinuclear antibody positivity"
    term:
      id: HP:0003493
      label: "Antinuclear antibody positivity"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003493 | Antinuclear antibody positivity | Very frequent (99-80%)"
    explanation: "Orphanet records antinuclear antibody positivity as a very frequent (80-99%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Oligoarthritis"
  category: Musculoskeletal
  subtype: Oligoarticular
  frequency: VERY_FREQUENT
  description: "Oligoarthritis is reported as a very frequent (80-99%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Oligoarthritis"
    term:
      id: HP:0040313
      label: "Oligoarthritis"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0040313 | Oligoarthritis | Very frequent (99-80%)"
    explanation: "Orphanet records oligoarthritis as a very frequent (80-99%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Uveitis"
  category: Ophthalmologic
  subtype: Oligoarticular
  frequency: FREQUENT
  description: "Uveitis is reported as a frequent (30-79%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Uveitis"
    term:
      id: HP:0000554
      label: "Uveitis"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000554 | Uveitis | Frequent (79-30%)"
    explanation: "Orphanet records uveitis as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Joint hypermobility"
  category: Musculoskeletal
  subtype: Oligoarticular
  frequency: FREQUENT
  description: "Joint hypermobility is reported as a frequent (30-79%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Joint hypermobility"
    term:
      id: HP:0001382
      label: "Joint hypermobility"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001382 | Joint hypermobility | Frequent (79-30%)"
    explanation: "Orphanet records joint hypermobility as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Failure to thrive"
  category: Constitutional
  subtype: Oligoarticular
  frequency: FREQUENT
  description: "Failure to thrive is reported as a frequent (30-79%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Failure to thrive"
    term:
      id: HP:0001508
      label: "Failure to thrive"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001508 | Failure to thrive | Frequent (79-30%)"
    explanation: "Orphanet records failure to thrive as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Knee osteoarthritis"
  category: Musculoskeletal
  subtype: Oligoarticular
  frequency: FREQUENT
  description: "Knee osteoarthritis is reported as a frequent (30-79%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Knee osteoarthritis"
    term:
      id: HP:0005086
      label: "Knee osteoarthritis"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0005086 | Knee osteoarthritis | Frequent (79-30%)"
    explanation: "Orphanet records knee osteoarthritis as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Increased serum interferon-gamma level"
  category: Immunologic
  subtype: Oligoarticular
  frequency: FREQUENT
  description: "Increased serum interferon-gamma level is reported as a frequent (30-79%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Increased serum interferon-gamma level"
    term:
      id: HP:0030356
      label: "Increased circulating interferon-gamma concentration"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0030356 | Increased serum interferon-gamma level | Frequent (79-30%)"
    explanation: "Orphanet records increased serum interferon-gamma level as a frequent (30-79%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Visual loss"
  category: Ophthalmologic
  subtype: Oligoarticular
  frequency: OCCASIONAL
  description: "Visual loss is reported as an occasional (5-29%) manifestation of oligoarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Visual loss"
    term:
      id: HP:0000572
      label: "Visual loss"
  evidence:
  - reference: ORPHA:85410
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000572 | Visual loss | Occasional (29-5%)"
    explanation: "Orphanet records visual loss as an occasional (5-29%) phenotype of oligoarticular juvenile idiopathic arthritis."
- name: "Rheumatoid factor positive"
  category: Immunologic
  subtype: Polyarticular RF-positive
  frequency: VERY_FREQUENT
  description: "Rheumatoid factor positive is reported as a very frequent (80-99%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Rheumatoid factor positive"
    term:
      id: HP:0002923
      label: "Rheumatoid factor positive"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002923 | Rheumatoid factor positive | Very frequent (99-80%)"
    explanation: "Orphanet records rheumatoid factor positive as a very frequent (80-99%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Polyarticular arthritis"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: VERY_FREQUENT
  description: "Polyarticular arthritis is reported as a very frequent (80-99%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Polyarticular arthritis"
    term:
      id: HP:0005764
      label: "Polyarticular arthritis"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0005764 | Polyarticular arthritis | Very frequent (99-80%)"
    explanation: "Orphanet records polyarticular arthritis as a very frequent (80-99%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Progressive joint destruction"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: FREQUENT
  description: "Progressive joint destruction is reported as a frequent (30-79%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Progressive joint destruction"
    term:
      id: HP:0005187
      label: "Progressive joint destruction"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0005187 | Progressive joint destruction | Frequent (79-30%)"
    explanation: "Orphanet records progressive joint destruction as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Interphalangeal joint erosions"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: FREQUENT
  description: "Interphalangeal joint erosions is reported as a frequent (30-79%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Interphalangeal joint erosions"
    term:
      id: HP:0006252
      label: "Interphalangeal joint erosions"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0006252 | Interphalangeal joint erosions | Frequent (79-30%)"
    explanation: "Orphanet records interphalangeal joint erosions as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Symetrical distal arthritis"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: FREQUENT
  description: "Symetrical distal arthritis is reported as a frequent (30-79%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Symetrical distal arthritis"
    term:
      id: HP:0040311
      label: "Symmetric polyarthritis"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0040311 | Symetrical distal arthritis | Frequent (79-30%)"
    explanation: "Orphanet records symetrical distal arthritis as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Synovitis"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: FREQUENT
  description: "Synovitis is reported as a frequent (30-79%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Synovitis"
    term:
      id: HP:0100769
      label: "Synovitis"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0100769 | Synovitis | Frequent (79-30%)"
    explanation: "Orphanet records synovitis as a frequent (30-79%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Reduced bone mineral density"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: OCCASIONAL
  description: "Reduced bone mineral density is reported as an occasional (5-29%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Reduced bone mineral density"
    term:
      id: HP:0004349
      label: "Reduced bone mineral density"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0004349 | Reduced bone mineral density | Occasional (29-5%)"
    explanation: "Orphanet records reduced bone mineral density as an occasional (5-29%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
- name: "Premature epimetaphyseal fusion"
  category: Musculoskeletal
  subtype: Polyarticular RF-positive
  frequency: OCCASIONAL
  description: "Premature epimetaphyseal fusion is reported as an occasional (5-29%) manifestation of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis in the Orphanet clinical phenotype dataset."
  phenotype_term:
    preferred_term: "Premature epimetaphyseal fusion"
    term:
      id: HP:0010588
      label: "Premature epimetaphyseal fusion"
  evidence:
  - reference: ORPHA:85435
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0010588 | Premature epimetaphyseal fusion | Occasional (29-5%)"
    explanation: "Orphanet records premature epimetaphyseal fusion as an occasional (5-29%) phenotype of rheumatoid factor-positive polyarticular juvenile idiopathic arthritis."
genetic:
- name: HLA-DRB1
  gene_term:
    preferred_term: HLA-DRB1
    term:
      id: hgnc:4948
      label: HLA-DRB1
  association: Susceptibility
  notes: >-
    HLA class II is the dominant genetic susceptibility locus for JIA, with
    `HLA-DRB1` alleles showing subtype-specific risk associations
    (HLA-DRB1*08 in oligoarticular and polyarticular JIA; HLA-DRB1*11
    additionally predisposing to oligoarticular JIA; HLA-DRB1*01 and
    HLA-DRB1*04 in RF-positive polyarticular JIA; HLA-DRB1*04 in systemic
    JIA). RF-positive polyarticular JIA is increasingly recognized as
    childhood-onset seropositive rheumatoid arthritis with distinct genetic
    architecture from RF-negative disease, though all polyarticular subtypes
    show shared immunogenetic features suggesting overlapping immune-mediated
    mechanisms.
  evidence:
  - reference: PMID:29037901
    reference_title: "HLA-DRB1 alleles and juvenile idiopathic arthritis: Diagnostic clues emerging from a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic predisposition to JIA is mainly due to HLA class II molecules (HLA-DRB1, HLA-DPB1), although HLA class I molecules and non-HLA genes have been implicated, too."
    explanation: Meta-analysis directly supports HLA-DRB1 as a primary genetic susceptibility locus for JIA.
  - reference: PMID:29037901
    reference_title: "HLA-DRB1 alleles and juvenile idiopathic arthritis: Diagnostic clues emerging from a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HLA-DRB1*08 is a strong factor predisposing to JIA, both for oligo-articular and poly-articular forms"
    explanation: Meta-analysis directly supports HLA-DRB1*08 as a predisposing allele for both oligoarticular and polyarticular JIA.
  - reference: PMID:29037901
    reference_title: "HLA-DRB1 alleles and juvenile idiopathic arthritis: Diagnostic clues emerging from a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "iii) HLA-DRB1*11"
    explanation: Meta-analysis confirms HLA-DRB1*11 as an additional predisposing allele for oligoarticular JIA.
  - reference: PMID:42266057
    reference_title: "Polyarticular juvenile idiopathic arthritis: insights from genetic studies on disease risk and pathogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rheumatoid factor (RF)-positive polyarticular JIA is increasingly considered a childhood-onset seropositive rheumatoid arthritis, whereas oligoarticular and RF-negative polyarticular JIA, although nonidentical, share substantial immunogenetic features."
    explanation: Recent review of genetic studies supports RF-positive polyarticular JIA as childhood-onset seropositive RA with distinct genetic architecture, while RF-negative polyarticular JIA shares immunogenetic features with oligoarticular JIA.
- name: Non-HLA immune-susceptibility genes (lymphocyte activation, cytokine signaling, immune regulation)
  association: Susceptibility
  notes: >-
    Recent genome-wide association studies (GWAS) and transcriptomic analyses
    have identified candidate genes mediating lymphocyte activation, cytokine
    signaling, and immune regulation in polyarticular JIA. These non-HLA loci
    show distinct, partially overlapping patterns across ILAR categories,
    reflecting the polygenic immune-mediated pathogenesis of JIA. Synovial
    atlas and spatial transcriptomic studies have further connected these
    genetic susceptibility loci to specific immune-cell states (T cell subsets,
    synovial macrophages, B cells) and organized inflammatory niches within
    the synovium, linking inherited risk alleles to the chronic
    arthritis-sustaining tissue environment.
  evidence:
  - reference: PMID:42266057
    reference_title: "Polyarticular juvenile idiopathic arthritis: insights from genetic studies on disease risk and pathogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Classical HLA and non-HLA studies established the polygenic immune-mediated pathogenesis of JIA with distinct, partially overlapping, genetic architectures across the International League of Associations for Rheumatology categories."
    explanation: Recent review establishes polygenic immune-mediated pathogenesis of JIA with distinct genetic architectures across ILAR categories.
  - reference: PMID:42266057
    reference_title: "Polyarticular juvenile idiopathic arthritis: insights from genetic studies on disease risk and pathogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recent subtype-integrative genome-wide association studies and transcriptomic and chromatin-interaction analyses prioritized candidate genes mediating lymphocyte activation, cytokine signaling, and immune regulation."
    explanation: GWAS and transcriptomic studies identify candidate genes for lymphocyte activation, cytokine signaling, and immune regulation in polyarticular JIA pathogenesis.
  - reference: PMID:42266057
    reference_title: "Polyarticular juvenile idiopathic arthritis: insights from genetic studies on disease risk and pathogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Synovial atlas and spatial transcriptomic studies have further connected genetic susceptibility to immune-cell states and organized inflammatory niches, linking inherited risk to the chronic arthritis-sustaining tissue environment."
    explanation: Synovial atlas studies link genetic susceptibility loci to specific immune-cell states and inflammatory tissue niches in polyarticular JIA.
treatments:
- name: NSAIDs
  description: >-
    Non-steroidal anti-inflammatory drugs are first-line symptom control
    for active arthritis and a useful diagnostic/therapeutic trial in
    early disease.
  treatment_term:
    preferred_term: NSAID therapy
    term:
      id: MAXO:0000221
      label: NSAID therapy
- name: Intra-articular and Systemic Glucocorticoids
  description: >-
    Intra-articular steroid injection (most often triamcinolone) is
    standard for oligoarticular JIA. Short-course systemic
    glucocorticoids are used as a bridge to DMARDs and as front-line
    therapy in active systemic JIA.
  treatment_term:
    preferred_term: glucocorticoid therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: triamcinolone
      term:
        id: CHEBI:9667
        label: triamcinolone
- name: Methotrexate (conventional DMARD)
  description: >-
    Methotrexate is the conventional synthetic DMARD of first choice for
    polyarticular and extended-oligoarticular JIA, slowing radiographic
    progression and inducing remission.
  treatment_term:
    preferred_term: methotrexate therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: methotrexate
      term:
        id: CHEBI:44185
        label: methotrexate
- name: TNF, IL-1, and IL-6 Inhibitor Biologics
  description: >-
    Biologic DMARDs targeting TNF (etanercept, adalimumab), IL-1
    (anakinra, canakinumab), and IL-6 (tocilizumab) are central to
    treatment of JIA refractory to methotrexate. In systemic JIA, IL-1 and
    IL-6 inhibitors are increasingly used as early therapy alongside
    short-course glucocorticoids.
  treatment_term:
    preferred_term: biologic DMARD therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: etanercept
      term:
        id: NCIT:C2381
        label: Etanercept
    - preferred_term: adalimumab
      term:
        id: NCIT:C65216
        label: Adalimumab
    - preferred_term: anakinra
      term:
        id: NCIT:C38717
        label: Anakinra
    - preferred_term: canakinumab
      term:
        id: NCIT:C80971
        label: Canakinumab
    - preferred_term: tocilizumab
      term:
        id: NCIT:C84217
        label: Tocilizumab
  evidence:
  - reference: PMID:39317417
    reference_title: "EULAR/PReS recommendations for the diagnosis and management of Still's disease, comprising systemic juvenile idiopathic arthritis and adult-onset Still's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The optimal therapeutic strategy relies on early use of interleukin (IL-1 or IL-6 inhibitors associated to short duration glucocorticoid (GC)."
    explanation: EULAR/PReS recommendations directly support early IL-1 or IL-6 inhibitor therapy plus short-course glucocorticoids for systemic JIA / Still's disease.
  - reference: PMID:38756937
    reference_title: "Diagnosing and Treating Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease as Part of the Still's Disease Continuum."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recently, targeted therapies such as interleukin (IL)-1 and IL-6 inhibitors have become available for the treatment of sJIA and AOSD."
    explanation: Supports availability of IL-1 and IL-6 inhibitor biologics for systemic JIA.
notes: >-
  This entry is a root-level dismech record organising the ILAR categories
  of juvenile idiopathic arthritis. Subtype-specific pathophysiology,
  genetics, complications (notably uveitis in oligoarticular JIA and
  macrophage activation syndrome in systemic JIA), and subtype-tailored
  therapy are scoped as follow-up dismech entries.
disease_term:
  preferred_term: juvenile idiopathic arthritis
  term:
    id: MONDO:0011429
    label: juvenile idiopathic arthritis
📚

References & Deep Research

Deep Research

1
Juvenile Idiopathic Arthritis Deep Research Fallback ▸

Juvenile Idiopathic Arthritis Deep Research Fallback

Provider Attempts

No deep-research provider was invoked for this root-level entry. There is no existing subtype dismech file for any ILAR category, so this record was curated directly from the verified literature already cached in references_cache/ that addresses JIA at the umbrella level.

Integrated Literature Synthesis

Juvenile idiopathic arthritis (JIA, MONDO:0011429) is an umbrella term for the chronic arthritides of childhood beginning before 16 years of age and persisting for at least six weeks, after exclusion of infective, traumatic, malignant, and other defined causes. The International League of Associations for Rheumatology (ILAR) criteria stratify JIA into seven clinically distinct categories — oligoarticular, polyarticular rheumatoid-factor-negative, polyarticular rheumatoid- factor-positive, systemic, psoriatic, enthesitis-related, and undifferentiated. PMID:29848426 ("Spectrum of Joint Deformities in Children with Juvenile Idiopathic Arthritis") cites the ILAR criteria as the operational basis for cohort enrolment in JIA studies.

Mechanistic axis: autoimmune vs autoinflammatory. PMID:29037901 frames the heterogeneity directly: "Juvenile Idiopathic Arthritis (JIA) is characterized with a variable pattern of articular involvement and systemic symptoms and, thus, it has been classified in several subtypes." Oligoarticular, polyarticular and RF-positive forms have an adaptive-autoimmune flavour with HLA-class-II linkage (HLA-DRB108, 01, *04 alleles depending on subset); systemic JIA is dominated by innate-immune activation with prominent IL-1 and IL-6 signalling.

PMID:38756937 and PMID:39317417 establish the Still's disease continuum between systemic JIA and adult-onset Still's disease, and define the modern therapeutic strategy: "The optimal therapeutic strategy relies on early use of interleukin (IL-1 or IL-6 inhibitors associated to short duration glucocorticoid (GC)." This is captured here as a separate Systemic Autoinflammation (sJIA) pathophysiology node.

Synovial mechanism atomic decomposition. Per the PR review feedback, the original single Synovial Inflammation node has been decomposed into three atomic nodes connected via downstream edges:

  1. Synovial Leukocyte Infiltration — T-cell and macrophage recruitment to the synovial membrane (UBERON:0002018, CL:0000235, GO:0006955 ABNORMAL).
  2. Synovial Hyperplasia — synoviocyte proliferation (CL:0000214).
  3. Cytokine-Mediated Articular Damage — TNF / IL-1 / IL-6 -driven cartilage and bone destruction (GO:0001816 INCREASED).

Chronic anterior uveitis is the major extra-articular complication of oligoarticular JIA and a leading cause of visual morbidity if unscreened. It is now captured as a subtype-qualified phenotype (HP:0012122 Anterior uveitis, temporality: CHRONIC, subtype: Oligoarticular). Acute symptomatic uveitis also occurs in enthesitis-related JIA but is not the same phenotype.

Treatment ladder. NSAIDs (MAXO:0000221), intra-articular and short-course systemic glucocorticoids, methotrexate as the conventional synthetic DMARD of first choice for polyarticular / extended- oligoarticular JIA, and biologic DMARDs targeting TNF (etanercept, adalimumab), IL-1 (anakinra, canakinumab), and IL-6 (tocilizumab), with IL-1 / IL-6 inhibitors moving earlier in the treatment paradigm for systemic JIA per the EULAR/PReS recommendations.

Out of scope for the root entry

  • Subtype-specific molecular details and complication profiles (macrophage activation syndrome in sJIA, the full spectrum of drug-specific dosing and adverse effects, etc.). Scoped as follow-up dismech entries per ILAR category.
  • Genetic-association detail beyond HLA-DRB1 — additional susceptibility loci (PTPN22, IL2RA, IL6, IL10) and the genetic overlap with adult rheumatoid arthritis are scoped as follow-up.
  • The Still's-disease end of the continuum in adults (adult-onset Still's disease) — should be its own dismech entry rather than duplicated here.