Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 12 4 2013 12 15 321 330 EN Sasan Fallahi Internal Medicine Division, Baharloo Hospital, Tehran University of Medical Sciences, Tehran, Iran AND Rheumatology Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Mahdi Mahmoudi Rheumatology Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Mohammad Hossein Nicknam Molecular Immunology Research Center, Tehran University of Medical Sciences, Tehran, Iran Farhad Gharibdoost Rheumatology Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Elham Farhadi Department of Haematology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Azad Saei Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Keramat Nourijelyani Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Nooshin Ahmadzadeh Rheumatology Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran Ahmad Reza Jamshidi Rheumatology Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran 2015 10 16 The aim of this study was to assess the role of HLA-B*27 and it’s subtypes in determining severity and clinical manifestations of ankylosing spondylitis (AS). A total of 163 AS patients were assessed for clinical manifestations and severity using structured questionnaires. HLA-B*27 screening and B*27 sub-typing were performed by PCR. One hundred twenty two patients (74.8%) were B*27 positive. The male to female ratio, peripheral arthritis, steroid use, intense dorsal kyphosis and decrease of cervical slope had a significantly higher frequency in B*27 positive patients  compared  to  B*27 negative ones (p=0.01,  0.001,  0.01,  0.04  and  0.04,  respectively). However,  the  age  of  diagnosis  was significantly lower in B*27 positive patients (p=0.005). Trend in uveitis and some severity markers including: BASMI and ASQoL were toward higher values in B*27 positive group with no significant difference. After controlling confounding variables, significant relationship was found  only between B*27 and BASMI (p=0.01). B*27 subtypes in patients were included B*2705: 48.4%, B*2702: 42.6%, B*2704: 5.7% and B*2707: 3.3%. No significant differences were seen for severity markers and clinical manifestations between subtypes; although trend toward lower values of severity markers, less intense dorsal kyphosis and less decrease of cervical slope were observed in B*2704 and B*2707 versus other polymorphisms. Clinical features and severity of AS is influenced by HLA-B*27. Trend  toward higher severity markers in B*2705 and B*2702 versus other  polymorphisms might be subject of interest for evaluation in other ethnicities with concentration to other novel susceptibility genes co-inherited in each B*27 subtype. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/495 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/495/549