title: HLA-B27 subtypes and tumor necrosis factor alpha promoter region polymorphism in Iranian patients with ankylosing spondylitis.
abstract: BACKGROUND
  HLA-B27 is an MHC class I molecule that is strongly associated with ankylosing spondylitis (AS). TNF-alpha, as an important cytokine in inflammatory joint disease, might have a role in the process of AS. This study was performed to determine HLA-B27 subtypes among Iranian patients with AS, and to investigate TNF-alpha gene polymorphisms in the patient groups.
  
  
  METHODS
  Ninety seven AS patients (74 HLA-B27-positive and 23 HLA-B27-negative) and 137 healthy normal subjects (2 HLA-B27-positive) were enrolled in this study. HLA-B27 positive patients were screened using the polymerase chain reaction, with sequence specific primers (PCR-SSP), for B*27 subtyping. All patients and the controls were also investigated for determination of TNF-alpha polymorphisms using the same method.
  
  
  RESULTS
  Just two subtypes were detected in our patients, namely B*2705 (63.4%) and B*2702 (36.6%). The study of TNF-alpha polymorphisms at position -238 showed that the A allele and AA genotype were significantly over-represented in all patient groups in comparison with the control group (p < 0.001). At position -308, while the A allele and AA genotype were significantly over-represented in the whole patient group (p = 0.01), there was no significant difference between the AS groups and the control group.
  
  
  CONCLUSIONS
  It could be suggested that a polymorphism within the TNF-alpha gene at -238 play an important role in AS, although this polymorphism was not related to HLA-B27 subtypes.
authors.affiliation: Molecular Immunology Research Center, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran, Rheumatology Research Centre, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran. nicknam_m@yahoo.com
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Nicknam
authors.forename: Mahdi
authors.initials: M
authors.lastname: Mahmoudi
authors.forename: Ali Akbar
authors.initials: AA
authors.lastname: Amirzargar
authors.forename: Ahmad Reza
authors.initials: AR
authors.lastname: Jamshidi
authors.forename: Nima
authors.initials: N
authors.lastname: Rezaei
authors.forename: Behrouz
authors.initials: B
authors.lastname: Nikbin