P631. ERAP-1 gene polymorphisms in Turkish patients with inflammatory bowel diseases and anyklosing spondylitis
Although genetic factors are known to play a crucial role in the pathogenesis of ankylosing spondylitis (AS), little is known about the molecular mechanisms that are responsible. In that context, endoplasmic reticulum aminopeptidase 1 (ERAP1) gene has been suggested as the most important factor in genetic susceptibility of AS, in addition to HLA-B27. However, there is little known about the relationship between ERAP1 gene and IBD.
The aim of this study is to investigate the prevalence and role of ERAP1 in the pathogenesis of AS as well as inflammatory bowel disease (IBD).
We included 273 consecutive AS with IBD, 50 Crohn's disease, 39 Ulcerative Colitis patients and 60 patients with enteropatic arthritis and 230 blood donors as healthy control subjects. DNA isolation from the participants' blood samples was performed automatically by the QIAGEN station and we investigated the presence of ERAP1 gene single nucleotide polymorphisms (SNPs) (rs26653) by using the method of competitive allele-specific PCR. We also determined the subgroups of HLA-B27 by PCR-Sequence Specific Primer (SSP). Hardy-Weinberg equilibrium (HWE) testing was carried out for all patient and healthy controls.
The mean age of AS patients were 38.3±11.8, Crohn patients 39.8±12.9, Ulcerative colitis 38.9±12.5, enteropatic arthritis 38.3±11.8 and controls were 38±8.9 years, respectively. The rates of HLA-B27 positivity were 74.3% in AS patients, 18.9% in Crohn's patients, 21.2% in UC patients, 33% in enteropathic arthritis, while this was 4.7% in the control group. We detected rs26653 SNP C/C homozygote genotypes in 35 AS patients (12.8%) and 8 controls (3.5.%), in 11 Crohn (22%) and control 8 (3.5%), in 7 UC patients (18%), in 5 enteropathic arthritis (8.3%) and 8 controls (3.5%). The frequencies of rs26653 SNP C/C homozygous genotypes in patients with AS, Crohn and Ulcerative colitis were found to be statistically significant higher than when compared than that of healthy controls (OR 4.08, 95% CI 1.85–8.98, p = 0.0005; OR 7.82, 95% CI 2.9–20.07, P < 0.00001; OR 6.07, 95% CI 2.06–17.8, P = 0.00001, respectively). rs26653 SNP C/C homozygote genotype frequency in enteropathic arthritis patients when compared to that of the control group wasn't statistically significant (OR 2.39, 95% CI 0.81–7.35, P = 0.113).
In our study, our study results demonstrated for the first time that genetic polymorphism in ERAP1 gene single nucleotide polymorphism, rs 26653 is associated with Crohn's disease and Ulcerative colitis in Turkish population. ERAP1 gene, rs 26653 polymorphism plays a role in the diseases pathogenesisof AS, Crohn's disease and Ulcerative colitis in a Turkish population.