HLA-B27 subtypes and tumor necrosis factor alpha promoter region polymorphism in Iranian patients with ankylosing spondylitis.
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.
Nicknam
Mohammad Hossein
MH
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
Mahmoudi
Mahdi
M
Amirzargar
Ali Akbar
AA
Jamshidi
Ahmad Reza
AR
Rezaei
Nima
N
Nikbin
Behrouz
B