Determination of clinical and demographic characteristics and HLA alleles associated with severe spinal involvement in ankylosing spondylitis

Our aims in this study are; comparing the frequencies of HLA alleles in ankylosing spondylitis (AS) patients in Turkish society is to identify alleles that may be associated with disease severity and severe spinal involvement in AS patients. A total of 100 AS patients with symptom duration over 10 years who applied to our outpatient clinic between December 2022 and June 2023 were included in the study. Cervical, lumbar and sacroiliac/pelvis vertebral radiographs of the patients taken within the last 2 years were examined. Sequence specific oligonucleotide polymerase chain reaction (SSO-PCR) low resolution method was used for HLA typing. HLA typing test results of 100 healthy people who applied to the Oncology Hospital Tissue Typing laboratory as donors between 2010 and 2015 were used to form the control group. The data were evaluated using appropriate statistical methods. Of the 100 patients included in the study, 62 were men and 38 were women. Like epidemiology studies, HLA-B*27 was found positive in 72% of AS patients and 8% in healthy controls. HLA-A*02, HLA-A*02 homozygous, HLA-B*27, HLA-C*02 were alleles with increased frequency in AS patients (p corrected for each: <0.001). HLA-B*35 (p corrected: 0.006) and HLA-C*04 (p corrected: 0.003) were the alleles that were common in healthy controls and were protective against the disease. In univariate analysis, the frequency of syndesmophytes was increased in those who were HLA-A*02 homozygous (p:0.040), and the frequency of bilateral stage 4 sacroiliitis was increased in those who were HLA-B*27 positive (p:0.033). The frequency of bamboo development was increased in HLA-DRB1*04 negative patients (p:0.019). In the multivariate decision tree model, a relationship was found between syndesmophytes, hip involvement, high mSASSS score, being homozygous for HLA-A*02, and male gender. Those with HLA-B*27 positive had earlier age at diagnosis (p:0.001), longer disease duration (p:0.009), family history (p:0.003), bilateral stage 4 sacroiliitis (p:0.033) and higher mSASSS scores (respectively p:0.044, p:0.042). As a result, HLA alleles that were associated with disease development and radiographic severity were detected in this study.