title: Prevalence and distribution of autoimmune diseases in 368 rheumatoid arthritis families.
abstract: OBJECTIVE
  To investigate whether frequency of rheumatoid arthritis (RA) and/or other autoimmune (AI) disorders was increased in RA French Caucasian families among the first- (FDR) and second-degree relatives (SDR), and to test whether the presence of AI disease family history identified a specific RA subset.
  
  
  METHODS
  We conducted telephone interviews to obtain histories of AI diseases among the FDR and SDR of 368 RA probands, belonging either to trio or affected sib-pair (ASP) families. All the AI diagnoses were confirmed by the physician of the affected relative.
  
  
  RESULTS
  Probands of the ASP families were characterized by older age at RA onset, longer disease duration, and larger family size versus trio families. In the trio families, the prevalence of AI diseases was 6.05% (4.76%-7.57%) in FDR and 2.40% (1.85%-3.06%) in SDR. In ASP families, the prevalence of AI diseases was, respectively, 10.24% (8.68%-11.97%) and 1.79% (1.41%-2.25%). The most frequent AI diseases among relatives were RA, thyroid AI diseases, and vitiligo. In trio families, a proband with a mean age of RA onset < 30 years was associated with AI disease prevalence in the relatives, and male gender was associated with prevalence of RA among the FDR.
  
  
  CONCLUSIONS
  The prevalence of AI diseases is increased, particularly among FDR, in French RA families, and some characteristics of the RA proband seem to be associated with prevalence of AI diseases in families.
authors.affiliation: GenHotel-EA 3886, University Evry-Paris 7 Medical School, Evry-Genopole, France. laetitia.michou@lrb.aphp.fr
authors.forename: Laëtitia
authors.initials: L
authors.lastname: Michou
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Rat
authors.forename: Sandra
authors.initials: S
authors.lastname: Lasbleiz
authors.forename: Thomas
authors.initials: T
authors.lastname: Bardin
authors.forename: François
authors.initials: F
authors.lastname: Cornélis
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000150:complications* / Q000453:epidemiology*; D001327:Autoimmune Diseases / Q000150:complications* / Q000453:epidemiology*; D018450:Disease Progression; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010375:Pedigree; D015995:Prevalence; D012737:Sex Factors