title: Diagnostic value of anti-cyclic citrullinated peptides and association with HLA-DRB1 shared epitope alleles in African rheumatoid arthritis patients.
abstract: BACKGROUND
  The purpose of this study was to examine the diagnostic performance of autoantibodies against citrullinated peptides/proteins (ACPA) and to determine the prevalence of HLA-DRB1 shared epitope alleles (SE) in African patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Serum levels of anti-cyclic citrullinated peptides antibodies (anti-CCP2, anti-CCP3), IgM and IgA rheumatoid factors (RF) were measured by enzyme-linked immunosorbent assay in the serum of 56 consecutive RA patients regularly followed in the Rheumatology Unit of the School of Medicine, University of Yaoundé, Yaoundé, Cameroon. Genotyping of HLA-DRB1 alleles was performed by polymerase chain reaction and hybridization with sequence-specific oligonucleotide probes on microbeads arrays. Fifty-one patients with other inflammatory rheumatic diseases and 50 healthy individuals were included as controls.
  
  
  RESULTS
  An anti-CCP2 assay showed the best diagnosis sensitivity (82%) and specificity (98%) with high positive predictive (PPV) (96%) and negative predictive values (NPV) (91%). Thirty percent of RA patients were carrying at least one copy of the HLA-DRB1 shared epitope (SE) compared to 10% and 14% of patients with other inflammatory rheumatic diseases and healthy individuals, respectively. The presence of the SE was associated with the production of ACPA.
  
  
  CONCLUSIONS
  Anti-CCP2 antibodies are useful markers of RA in African patients. In this cohort, the prevalence of the SE is higher in RA patients than in controls but lower than that reported in patient cohorts of European ancestry. The discrepancy between the high prevalence of ACPA-positive patients and the relatively low number of SE-positive cases suggest that, in addition to SE, other genetic factors control the development of ACPA in African RA patients.
authors.affiliation: Unit of Rheumatology, Department of Internal Medicine, School of Medicine, University of Yaoundé, Yaoundé, Cameroon.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Singwe-Ngandeu
authors.forename: Axel
authors.initials: A
authors.lastname: Finckh
authors.forename: Sylvette
authors.initials: S
authors.lastname: Bas
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Tiercy
authors.forename: Cem
authors.initials: C
authors.lastname: Gabay
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000208:ethnology / Q000235:genetics*; D015415:Biomarkers / Q000097:blood; D044383:Black People / Q000208:ethnology / Q000235:genetics*; D002163:Cameroon / Q000453:epidemiology; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D005260:Female; D006684:HLA-DR Antigens / Q000097:blood / Q000235:genetics*; D059811:HLA-DRB1 Chains; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000097:blood* / Q000276:immunology; D011237:Predictive Value of Tests; D055815:Young Adult
chemical_list: D015415:Biomarkers; D000939:Epitopes; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide