title: Juvenile idiopathic arthritis and HLA class I and class II interactions and age-at-onset effects.
abstract: OBJECTIVE
  The aim of this study was to quantitate risk and to examine heterogeneity for HLA at high resolution in patients with the most common subtypes of juvenile idiopathic arthritis (JIA), IgM rheumatoid factor-negative polyarticular JIA and oligoarticular JIA. Use of 4-digit comprehensive HLA typing enabled great precision, and a large cohort allowed for consideration of both age at disease onset and disease subtype.
  
  
  METHODS
  Polymerase chain reaction-based high-resolution HLA typing for class I and class II loci was accomplished for 820 patients with JIA and 273 control subjects. Specific HLA epitopes, potential interactions of alleles at specific loci and between loci (accounting for linkage disequilibrium and haplotypic associations), and an assessment of the current International League of Associations for Rheumatology classification criteria were considered.
  
  
  RESULTS
  An HLA-DRB1/DQB1 effect was shown to be exclusively attributable to DRB1 and was similar between patients with oligoarticular JIA and a younger subgroup of patients with polyarticular JIA. Furthermore, patients with polyarticular JIA showed age-specific related effects, with disease susceptibility in the group older than age 6 years limited to an effect of the HLA-DRB1*08 haplotype, which is markedly different from the additional susceptibility haplotypes, HLA-DRB1*1103/1104, found in the group with oligoarticular JIA and the group of younger patients with polyarticular JIA. Also in contrast to findings for oligoarticular JIA, patients with polyarticular arthritis had no evidence of an HLA class I effect. Markers associated with a reduced risk of disease included DRB1*1501, DRB1*0401, and DRB1*0701. DRB1*1501 was shown to reduce risk across the whole cohort, whereas DRB1*0401 and DRB1*0701 were protective for selected JIA subtypes. Surprisingly, the disease predisposition mediated by DPB1*0201 in individuals without any disease-predisposing DRB1 alleles was great enough to overcome even the very strong protective effect observed for DRB1*1501.
  
  
  CONCLUSIONS
  Inherited HLA factors in JIA show similarities overall as well as differences between JIA subtypes.
authors.affiliation: Children's Hospital Oakland Research Institute, Oakland, California, USA.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Hollenbach
authors.forename: Susan D
authors.initials: SD
authors.lastname: Thompson
authors.forename: Teodorica L
authors.initials: TL
authors.lastname: Bugawan
authors.forename: Mary
authors.initials: M
authors.lastname: Ryan
authors.forename: Marc
authors.initials: M
authors.lastname: Sudman
authors.forename: Miranda
authors.initials: M
authors.lastname: Marion
authors.forename: Carl D
authors.initials: CD
authors.lastname: Langefeld
authors.forename: Glenys
authors.initials: G
authors.lastname: Thomson
authors.forename: Henry A
authors.initials: HA
authors.lastname: Erlich
authors.forename: David N
authors.initials: DN
authors.lastname: Glass
mesh_terms: D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D000483:Alleles; D001171:Arthritis, Juvenile / Q000235:genetics* / Q000276:immunology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006239:Haplotypes; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000276:immunology; D006801:Humans; D008297:Male; D016017:Odds Ratio; D018579:Patient Selection; D016133:Polymerase Chain Reaction; D025341:Principal Component Analysis; D012737:Sex Factors
chemical_list: D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II