engleski

Association of IL-23R Gene Polymorphism with Inflammatory Bowel Disease in the Croatian Population

Inflammatory bowel disease (IBD) is a general term that covers a group of inflammatory disorders of the gastrointestinal tract: Crohn´s disease (CD) and ulcerative colitis (UC). The IBD is a complex interplay of genetic, environmental, and immunologic factors. A single-nucleotide polymorphism (SNP) rs11209026, which encodes a missense allele change (G>A) and a nonsynonymous amino acid substitution (Arg381Gln) in a subunit of the human IL-23 receptor has been associated with an altered TH17 inflammatory response. Uncommon glutamine allele had significantly lower frequency in different CD cohorts compared with healthy subjects suggesting that it confers strong protection against CD. The aim of this study was to investigate the association of the SNP rs11209026*A/Gln variant and genotype– phenotype relationship in Croatian IBD population. Genomic DNA was isolated from venous EDTA blood of 100 healthy controls and 132 IBD patients. Genotyping was carried out using LightCycler allele discrimination method. Detection was based on fluorescent resonance energy transfer (FRET) and melting curve analysis of PCR products. In this study we determine two genotypes in both tested groups: dominant homozygote (GG) and heterozygote (GA). Homozygous AA carriers were not detected in either group. Genotype frequencies of the IL23R Arg381Gln SNP were in accordance with the Hardy- Weinberg equilibrium. Frequency of allele A in IBD group was 0.023 while in control group was 0.07. Total minor allele frequency (MAF) was 0.043. A significant decrease of allele A in IBD group relative to group of healthy subjects (OR=0.31 ; 95% CI=0.12-0.82 ; Fisher exact P=0.019) was observed, suggesting a possible protective role against IBD. In contrast, no significant difference in genotype frequencies between IBD cases and controls was found (0.06 vs 0.106, GA genotype, cases vs controls, OR=0.54 ; 95% CI=0.2- 1.54, Fisher exact P=0.246). Our results referee that further studies based on a larger number of samples and/or comprising more SNPs are needed to confirm or reject the reported phenotype–genotype associations.

Inflammatory bowel disease ; SNP

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