title: HLA-DRB1 and HLA-DQB1 allele associations in an Albanian patient population with rheumatoid arthritis: correlations with the specific autoantibody markers and inter-population DRB1 allele frequency variability.
abstract: The prevalence of rheumatoid arthritis and its specific autoantibodies varies in different populations. This variability depends on the genetic polymorphism of the immune response genes among which the HLA system plays a major role. In this context, we studied the HLA-DRB1 and HLA-DQB1 first-level allele frequencies in 100 Albanian patients with rheumatoid arthritis (RA), and taking into account their rheumatoid factor (RF) and anticitrullinated peptide antibodies (ACPA) serologic subgroups, we compared them with the respective frequencies in a population of 191 Albanian individuals without known pathology. No differences were found between the controls and the RA patient group as a whole, but three statistically significant differences were found: an increase in DRB1*04 among ACPA+, RF+ and ACPA+/RF+ patients, a significant decrease in DRB1*11 among ACPA+/RF+ and also a decrease in DRB1*13 among RF+ patient subgroups. Comparing allele frequencies of putatively associated RA alleles in different European populations revealed a significant negative correlation between the RA predisposing DRB1*04 and protective DRB1*11 allele frequencies. A statistically significant correlation was also found between RA prevalence rates and DRB1*04 as well as DRB1*11 frequencies. The relatively low frequencies of DRB1*04 and high DRB1*11 in the Albanian population might explain the rather low positivity rate of ACPA and RF antibodies among the Albanian RA patients. These specific association patterns suggest that this first study of RA in an Albanian population should be followed up to include second level or higher definition of HLA alleles and to compare RA patterns among European populations.
authors.affiliation: Laboratory of Immunology and Histocompatibility, University Hospital Center of Tirana, Tiranë, Albania.
authors.forename: Margarita
authors.initials: M
authors.lastname: Prifti-Kurti
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Nunes
authors.forename: Erkena
authors.initials: E
authors.lastname: Shyti
authors.forename: Zamira
authors.initials: Z
authors.lastname: Ylli
authors.forename: Alicia
authors.initials: A
authors.lastname: Sanchez-Mazas
authors.forename: Genc
authors.initials: G
authors.lastname: Sulcebe
mesh_terms: D000328:Adult; D000415:Albania / Q000453:epidemiology; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis / Q000208:ethnology / Q000235:genetics* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D059866:HLA-DQ beta-Chains / Q000235:genetics*; D059811:HLA-DRB1 Chains / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology; D010641:Phenotype; D015995:Prevalence; D065840:Protective Factors; D012217:Rheumatoid Factor / Q000097:blood; D012307:Risk Factors; D044465:White People / Q000235:genetics
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D059811:HLA-DRB1 Chains; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor