title: Immunogenetic differences between patients with familial and non-familial rheumatoid arthritis.
abstract: OBJECTIVE
  To search for possible immunogenetic differencies between the patients with familial and non-familial rheumatoid arthritis (RA).
  
  
  METHODS
  The study compared 129 familial RA patients with 217 non-familial patients for the frequencies of HLA-DR antigens including DR4 subtypes, DR4-DQB1*0301 and DR4-DQB1*0302 haplotypes and HLA-B27 antigen as well as the age of disease onset and existence of rheumatoid factor or joint erosions.
  
  
  RESULTS
  Two major differences between familial and non-familial groups were found: firstly, familial RA patients had increased frequency of HLA-DR4 as compared with the non-familial RA group (68.2 v. 54.8%; p = 0.019). Secondly, the mean age at onset of RA was significantly lower in the familial than in the sporadic RA patients (42.0 v. 46.5 years; p = 0.0020) and the difference still remained when the DR4 positive and negative subgroups were compared separately.
  
  
  CONCLUSIONS
  These results confirm the more prominent association with HLA-DR4 in familial than in the non-familial cases and suggest that accumulation of HLA risk genes may, at least partly, explain the familial occurrence of the disease. Other susceptibility genes may also be concentrated in multiplex case families as suggested by an earlier age at the onset of RA in both HLA-DR4 positive and negative familial patients.
authors.affiliation: Turku Immunology Centre and Departments of Virology, Medical Microbiology and Medicine, University of Turku and Turku University Central Hospital, Turku, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Laivoranta-Nyman
authors.forename: T
authors.initials: T
authors.lastname: Möttönen
authors.forename: R
authors.initials: R
authors.lastname: Luukkainen
authors.forename: M
authors.initials: M
authors.lastname: Hakala
authors.forename: U
authors.initials: U
authors.lastname: Yli-Kerttula
authors.forename: P
authors.initials: P
authors.lastname: Hannonen
authors.forename: J
authors.initials: J
authors.lastname: Tuokko
authors.forename: A
authors.initials: A
authors.lastname: Toivanen
authors.forename: J
authors.initials: J
authors.lastname: Ilonen
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D005260:Female; D020022:Genetic Predisposition to Disease; D006684:HLA-DR Antigens / Q000097:blood; D015804:HLA-DR4 Antigen / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D015415:Biomarkers; D006684:HLA-DR Antigens; D015804:HLA-DR4 Antigen