Background The association between Ankylosing Spondylitis, Inflammatory Bowel Disease and candidate genes has been reported in different populations. Studies demonstrating this association in populations around the Mediterranean belt have not yet been reported.
Objectives We aimed at investigating the association between single nucleotide polymorphisms (SNPs) in these candidate genes; ERAP-1, IL-23R, STAT-3, JAK-2 and TNFRF1A and susceptibility to AS and IBD among an adult Turkish population. We also tested the role of these genes in clinical manifestations of AS and IBD
Methods The study consisted of a total of 562 subjects including 365 AS, 197 IBD patients and 230 ethically matched Turkish healthy controls. Definition of AS was made according to the modified New York criteria. Genotyping of the allelic variants of ERAP-1, IL-23R, STAT-3, JAK-2 and TNFRF1A SNPs was carried out with the competitive allele-specific polymerase chain reaction. Differences between genotypes and allele frequencies were compared using the Pearson's Chi-square test. The associations between ERAP1 SNPs and disease severity, clinical findings, were determined using the spearman correlation.
Results Healthy-control matched results revealed the ERAP-1 gene rs26653 polymorphism to increase disease risk in patients with AS, Chron's Disease and Ulcerative Colitis. (OR =1.97, p=0.0003, OR: 2.66; P<0.001ve OR: 1.67; P=0.067 respectively). In addition, it showed significant single-locus disease associations with parameters of disease severity (BASDAI and BASFI) in AS patients (r=0.829, P<0.001 and r=0.731, P<0.001 respectively). The strongest associated SNP in IL23R was rs112209032, which was shown to play a protective role in AS and IBD by significantly decreasing disease risk in AS when compared to the healthy control groups (OR =0.25, p=0.0001, and OR =0.37, p=0.0217).
Conclusions We were able to show that the IL-23R gene polymorphism can play a protective role against AS in the Turkish population. ERAP-1 gene polymorphism is associated with the pathogenesis and risk of development of AS and IBD. No association was seen with the extra articular manifestations of AS and IBD.In addition a possible relationship between ERAP-1 gene polymorphism and disease severity in ankylosing spondylitis patients is shown.
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Acknowledgements We would like to thank to “Ankara foundation for Medicine and Internal Medicine Research and Development Association” for funding this project.
Disclosure of Interest None declared
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