Ghrelin Gene Polymorphisms in Irritable Bowel Syndrome

Introduction/Objective: Irritable bowel syndrome (IBS) is a bowel disorder characterized by pain accompanying defecation or altered bowel habits, divided into diarrhea-predominant, constipation-predominant, and alternating subtypes, whose pathogenesis is considered to include disordered bowel motility. The hormone ghrelin is a growth hormone secretagogue which furthermore affects gastrointestinal motility. We study the association between its genetic polymorphisms and the risk for IBS. Methods: IBS patients meeting the Rome III criteria and controls similar in age and gender were recruited. Whole blood samples were used for genotyping via polymerase chain reaction and restriction fragment length polymorphism for the polymorphisms rs34911341, rs696217, and rs2075356. Results: Participants included 142 patients and 209 controls. The rs696217 GG genotype frequency was higher in patients (78.87%) compared to controls (55.5%). The rs696217 GT genotype was significantly less frequent among patients than in controls (OR 0.31, 95% CI 0.19-0.52), as was the T allele (OR 0.43, 95% CI 0.28-0.66). No significant differences in genotype distribution were found for the rs34911341 and rs2075356 polymorphisms between patients and controls. The genotype frequencies did not significantly differ between IBS subtype groups for any of the polymorphisms studied. Conclusions: The GG and GT genotypes of the rs696217 polymorphism, as well as the G-allele, demonstrate significant association with IBS susceptibility, while the T allele appears to bear a protective effect. Ghrelin's polymorphisms are plausibly involved in IBS pathogenesis, but do not correlate with any distinct IBS subtype.