effect of hla-b*27 and its subtypes on clinical manifestations and severity of ankylosing spondylitis in iranian patients.

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.