title: The Influence of the HLA-DRB1 rheumatoid arthritis shared epitope on the clinical characteristics and radiological outcome of psoriatic arthritis.
abstract: OBJECTIVE
  To investigate the associations of the HLA-DRB1 rheumatoid arthritis shared epitope (SE) with clinical characteristics and radiological outcome in patients with psoriatic arthritis (PsA).
  
  
  METHODS
  One hundred fifty-eight patients with well documented PsA and 250 controls were typed for HLA-DRB1 alleles including the SE by polymerase chain reaction. Clinical data collected on the patient group included disease subset, swollen and tender joint counts, the psoriasis area severity index (PASI), and the presence of radiological erosions. Clinical and radiological associations with HLA-DRB1 and SE alleles were determined.
  
  
  RESULTS
  There was an increased frequency of HLA-DR7 (41 vs 25%; puncorr = 0.001, OR 2.02, pcorr = 0.01) and a decreased frequency of HLA-DR2 (19 vs 28%; puncorr = 0.03, OR 0.59, pcorr = 0.3) in the patient population compared with controls. There was no significant difference in the frequency of HLA-DR1 and HLA-DR4 between patient and control populations. There was no significant difference in the prevalence of SE alleles between the patient and control populations (48 vs 54%). There was no increase in the prevalence of the SE in the polyarthritis subgroup, but there was a marginal decrease in those who remained in the oligoarthritis subgroup. There were no differences with respect to sex, age of onset of disease, family history, Health Assessment Questionnaire score, joint score, skin score, or nail score between those patients who were SE positive and those who were SE negative. However, significantly more patients who were SE positive developed radiological erosions (60 vs 43%; p = 0.03, OR 2.11).
  
  
  CONCLUSIONS
  Overall, the prevalence of the SE in patients with PsA did not differ from our control population. However, it was overrepresented in those who developed radiological erosions. It is possible that the SE does have a role in the clinical severity of PsA.
authors.affiliation: Royal National Hospital for Rheumatic Diseases and Bath Institute for Rheumatic Diseases, England.
authors.forename: Eleanor
authors.initials: E
authors.lastname: Korendowych
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dixey
authors.forename: Beverly
authors.initials: B
authors.lastname: Cox
authors.forename: Sharon
authors.initials: S
authors.lastname: Jones
authors.forename: Neil
authors.initials: N
authors.lastname: McHugh
mesh_terms: D000328:Adult; D000368:Aged; D015535:Arthritis, Psoriatic / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000235:genetics*; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000235:genetics*; D000939:Epitopes / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D006684:HLA-DR Antigens / Q000235:genetics*; D059811:HLA-DRB1 Chains; D059845:HLA-DRB4 Chains; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011859:Radiography; D012720:Severity of Illness Index
chemical_list: D000939:Epitopes; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D059845:HLA-DRB4 Chains