Association of CCK(1) Receptor Gene Polymorphisms and Irritable Bowel Syndrome in Korean

INTRODUCTION: Cholecystokinin (CCK) belongs to a group of endogenous molecules known as brain-gut neuropeptides and functions as a neuropeptide as well as a gut hormone. It remains unclear whether genetic variation of the CCK receptor plays a role in irritable bowel syndrome (IBS). The aim of this study was to determine and compare the allele and genotype frequencies of the CCK(1) receptor polymorphisms between healthy controls and patients with IBS. METHODS: Genotyping of 80 patients with IBS (who met the Rome III criteria) and 76 healthy controls was performed. We performed PCR amplification for the CCK(1) receptor intron 1 779 T > C and Exon 1 G > A. We confirmed polymorphisms by direct sequencing method. RESULTS: There was a significantly different trend for genotypic distributions of the CCK(1) receptor polymorphism between patients with IBS and healthy controls (p for trend = 0.048). The CCK(1) receptor intron 1 779 T >C polymorphic type was more common in patients with 'IBS-constipation predominant (IBS-C) and IBS-mixed (IBS-M) forms' (19/31, 61.3%) than healthy controls 32/76, 42.1% adjusted odd ratio 2.43, 95% Confidence interval 1.01-5.86). The genotypic distributions of the CCK(1) receptor exon 1 polymorphism were not significantly different between the two groups (p for trend = 0.223). CONCLUSIONS: CCK(1) receptor polymorphisms were associated with IBS. In particular, the CCK(1) receptor intron 1 779 T > C polymorphic type was associated with 'IBS-C and IBS-M'. Further studies are needed in larger number of patients with an even distribution of IBS subtypes.