title: HLA-DRB1 allele association with rheumatoid arthritis susceptibility and severity in Syria.
abstract: BACKGROUND
  Rheumatoid arthritis (RA) is a complex multifactorial chronic disease. The importance of human leukocyte antigen as a major genetic risk factor for RA was studied worldwide. Although it is widely distributed in different Syrian areas, studies of human leukocyte antigen (HLA) alleles' role are absent.
  
  
  OBJECTIVE
  The aim of our study was to determine the association of HLA-DRB1 alleles with the susceptibility and severity of RA in Syria.
  
  
  METHODS
  Eighty-six RA patients and 200 healthy controls from Syria were genotyped using polymerase chain reaction with sequence-specific primer (PCR-SSP). Anti-CCP antibodies were measured by ELISA. Rheumatoid factor (RF), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and disease activity score 28 (DAS-28) values were obtained from patients' medical records. DAS-28 was used to assess the clinical severity of the patients.
  
  
  RESULTS
  The HLA-DRB1*01, *04, and *10 frequencies showed a strong association with the disease susceptibility (OR = 2.29, 95% CI = 1.11-4.75, P = 0.022; OR = 3.16, 95% CI = 2.0 -4.8, P < 0.0001; OR = 2.43, 95% CI = 1.07-5.51, P = 0.029 respectively), while the frequencies of HLA-DRB1*11, and *13 were significantly lower in RA patients than in controls (OR = 0.49, 95% CI = 0.3-0.8, P = 0.004; OR = 0.32, 95% CI = 0.15-0.69, P = 0.002, respectively). The other HLA-DRB1 alleles showed no significant difference. The frequency of anti-CCP antibodies was higher in shared epitope (SE) positive patients compared with SE-negative patients (OR = 5.5, 95% CI = 2-15.1, P = 0.00054). DAS-28 of RA patients didn't show significant difference between the SE negative and the SE positive groups.
  
  
  CONCLUSIONS
  Our results indicate that HLA-DRB1*01, *04, and *10 alleles are related with RA, while HLA-DRB1*11 and *13 protect against RA in the Syrian population.
authors.affiliation: School of Pharmacy, University of Damascus, Syria. jamilmourad@live.com
authors.forename: Jamil
authors.initials: J
authors.lastname: Mourad
authors.forename: Fawza
authors.initials: F
authors.lastname: Monem
mesh_terms: D001172:Arthritis, Rheumatoid / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D059811:HLA-DRB1 Chains / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D013593:Syria
chemical_list: D059811:HLA-DRB1 Chains