title: Comparison of clinical and immunogenetic features in familial versus sporadic psoriatic arthritis.
abstract: OBJECTIVE
  To compare patients with familial versus sporadic psoriatic arthritis (PsA) with respect to clinical, radiological and immunogenetic features.
  
  
  METHODS
  All patients were identified from the University of Toronto Psoriatic Arthritis Clinic. Familial and sporadic PsA were distinguished based on the proband's self-reported history. The probands were compared at presentation to clinic with respect to: demographic information, age of onset of psoriasis and inflammatory arthritis, disease activity, disease damage, laboratory variables, functional class and HLA antigens. The two groups were compared using a univariate analysis.
  
  
  RESULTS
  In total 407 patients were included. Thirty-six patients (8.8%) were eliminated as they reported a family history of arthritis in the absence of psoriasis. Of the remaining 371 patients, 150 patients reported a positive family of either PsA or psoriasis. 221 patients (54.2%) had no family history of psoriatic arthritis, psoriasis, or "arthritis". The familial group were younger at presentation to clinic (p = 0.003), had an earlier age of onset of psoriasis (p = 0.001) and inflammatory arthritis (p = 0.001) and were more likely to be receiving treatment (p = 0.001). The mean number of actively inflamed joints was higher in the sporadic group (p = 0.035), along with a higher frequency of rheumatoid factor positivity (p = 0.04). Only the age of onset variables and medication use retained significance after correction for multiple comparisons.
  
  
  CONCLUSIONS
  In comparing probands with familial versus sporadic PsA, we noted a marked difference in the age of onset of psoriasis and inflammatory arthritis, along with other differences in several clinical variables. These differences may be helpful in identifying PsA patients with a stronger genetic predisposition.
authors.affiliation: University of Toronto Psoriatic Arthritis Clinic, University of Toronto, Toronto Hospital, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Rahman
authors.forename: C T
authors.initials: CT
authors.lastname: Schentag
authors.forename: M
authors.initials: M
authors.lastname: Beaton
authors.forename: D D
authors.initials: DD
authors.lastname: Gladman
mesh_terms: D000328:Adult; D017668:Age of Onset; D018501:Antirheumatic Agents / Q000627:therapeutic use; D015535:Arthritis, Psoriatic / Q000000981:diagnostic imaging / Q000235:genetics* / Q000276:immunology* / Q000503:physiopathology; D005260:Female; D006680:HLA Antigens / Q000032:analysis; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D011859:Radiography; D012217:Rheumatoid Factor / Q000097:blood; D012720:Severity of Illness Index
chemical_list: D018501:Antirheumatic Agents; D006680:HLA Antigens; D012217:Rheumatoid Factor