HLA-B*27 subtyping in patients with ankylosing spondilitis and its relation to disease activation in our region

Ankylosing Spondilitis (AS) [MIM 106300] is a chronic, systemic and inflammatory disease with unknown exact etiology, defined with the presence of pain in joints, progressive joint stiffness and inflammation in sacroiliac joints. This study was aimed to search for HLA-B*27 allele frequency and the distribution of HLA-B27 subtypes in DNAs obtained from blood samples of 121 AS patients (72 male and 49 female) and 20 subjects out of a control group consist of 400 healthy people using PCRSSP method.HLA-B27 positivity was determined at 95.05% frequency in AS patient group while it was 5% in the control group. HLA B*2701, B*2702, B*2705, B*2707, B*2708, B*2712, B*2723, B*2731, B*2740, B*2748, B*2756 subtypes were detected in AS patients. In the control group, B*2702, B*2705, B*2756 subtypes and differently from AS group, B*2753 subtype was found. The most frequent subtype was HLAB27*56 (68.7%) in AS patient group. In addition, HLA-B*2702 with 19.1% frequency, HLA-B*2748 with 2.60% frequency, HLA-B*2701, B*2705 and B*2740 with 1.74% frequency, HLA-B*2707, B*2708, B*2712 B*2723 and B*2731 with 0.87% frequency were found. HLA-B*2705 was the most frequent subtype which was 38.1% in the control group followed by HLA-B*2702 and B27*56 subtypes with 28.5% frequency and HLA-B*2753 subtype with 4.76% frequency were detected.In conclusion, HLA-B*27 positivity was seen at 95.05% frequency in AS patients in our region. The frequency of HLA-B*2756 subtype was detected significantly higher in AS patients compare to control group (68.7% vs. 37.5%; P=0.003). This result suggests that HLA-B*2756 might have a role in susceptibility to AS disease. As HLAB*2705 subtype was seen higher (38.1%) in the control group, there might be negative association between the disease and the subtype.Key words: Allele distribution, Ankylosing Spondilitis, HLA-B*27, PCR-SSP