title: Familial aggregation of juvenile idiopathic arthritis.
abstract: OBJECTIVE
  To estimate the degree of familial aggregation of juvenile idiopathic arthritis (JIA), determine whether the aggregation of JIA and the aggregation of type 1 diabetes mellitus (type 1 DM) overlap, and identify multiplex JIA pedigrees.
  
  
  METHODS
  Records of individuals with JIA or type 1 DM were probabilistically linked with records in the Utah Population Database (UPDB), a large computerized family history database. For each case of JIA or type 1 DM, 10 matched controls or 5 matched controls, respectively, were selected. All familial relationships among cases of JIA or type 1 DM were established. A familial risk score was calculated for each subject. For various levels of familial exposure to JIA or type 1 DM, one's risk (odds ratio [OR]) of developing JIA or type 1 DM was established (cases compared with controls). Recurrence risks for JIA were computed for relatives of JIA cases compared with relatives of controls. Extended JIA families were identified from a list of common ancestors.
  
  
  RESULTS
  Records of a total of 443 patients were linked with the UPDB. Of these, 381 (86.0%) met criteria for JIA. An increased risk for JIA was observed among relatives of probands with JIA. The prevalence of type 1 DM among JIA cases was higher than the US prevalence of type 1 DM (P < 0.003). The recurrence risk for JIA was significantly elevated among first-degree relatives of cases with JIA (OR 30.4). The overall prevalence of JIA was 28/100,000. Four extended JIA pedigrees were identified.
  
  
  CONCLUSIONS
  There is familial aggregation of JIA in the Intermountain West region of the US. We have demonstrated that multiplex JIA pedigrees can be identified using a genealogic database.
authors.affiliation: University of Utah School of Medicine, Salt Lake City, UT 84132, USA. sampath.prahalad@hsc.utah.edu
authors.forename: Sampath
authors.initials: S
authors.lastname: Prahalad
authors.forename: Elizabeth
authors.initials: E
authors.lastname: O'brien
authors.forename: Alison M
authors.initials: AM
authors.lastname: Fraser
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kerber
authors.forename: Geraldine P
authors.initials: GP
authors.lastname: Mineau
authors.forename: David
authors.initials: D
authors.lastname: Pratt
authors.forename: David
authors.initials: D
authors.lastname: Donaldson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bamshad
authors.forename: John
authors.initials: J
authors.lastname: Bohnsack
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D002648:Child; D016000:Cluster Analysis; D016208:Databases, Factual; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D005192:Family Health; D005260:Female; D005789:Genealogy and Heraldry; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D010375:Pedigree; D014589:Utah / Q000453:epidemiology