HLA-B27 subtypes and tumor necrosis factor alpha promoter region polymorphism in Iranian patients with ankylosing...

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.

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.

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.

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.