[Clinical, radiographic and biologic particularities of ankylosing spondylitis in Tunisian patients according to the presence or the absence of the HLA B27 and its sub-types].

To assess the clinical, radiographic and biologic particularities of ankylosing spondylitis (AS) in Tunisian patients according to HLA B27 and its sub-types statute. This was a case-control study that included 100 patients (85 males/15 females) with AS according to the modified New York criteria. Demographic, clinical, AS specific indexes, radiographic and biologic parameters were determined. HLA-B and B27 subtypes typing of all subjects were performed by PCR-SSP. Patients mean age was 38.4 years +/- 12.6 HLA-B27 was found in 62% of patients. The comparison of B27 positive and B27 negative patients revealed a correlation of B27 with age, male gender, family history of spondylarthropathies, age at disease onset, acute onset of the disease, inaugural spinal involvement, uveitis, bilateral and destructive hip arthritis as well as a high score of mSASSS. The most frequent sub-types of HLA B27 were B*2702 (49.2%) and B*2705 (36.3%). No significant difference of the clinical presentation of the disease or severity factors was found among these patients. This study confirmed the contribution of the HLA B27 to the determination of the clinical presentation of AS. The variability of factors linked to B27 may be explained by the polygenic model of the disease.