Serotonin transporter gene polymorphism in healthy adults and patients with irritable bowel syndrome

BACKGROUND/AIMS: Serotonin is thought to be an important neurotransmitter in the pathogenesis of irritable bowel syndrome (IBS). It is reported that functional polymorphism in the promotor region of the serotonin transporter gene is related with the subtypes of IBS and shows racial difference. However, a functional relation between polymorphism and IBS is not clear. The aim of this study was to investigate 5-hydroxytryptamine transporter (5-HTT) gene polymorphism in patients with IBS. METHODS: For fifty-six healthy controls and 33 patients with IBS fulfilling Rome II criteria, 5'-flank promotor region of 5-HTT gene was analyzed by polymerase chain reaction. RESULTS: The genotypes of healthy controls were S/S (57.1%), S/L (37.5%), and L/L (5.4%). Those of IBS patients were S/S (54.5%), S/L (36.4%), and L/L (9.1%). IBS patients were divided into three groups: diarrhea predominant (n=15; S/S, 40%; S/L, 53.3%; L/L, 6.7%), constipation predominant (n=12; S/S, 75.0%; S/L, 8.3%; L/L, 16.7%), diarrhea-constipation alternating type (n=6; S/S, 50%; S/L, 50%). There was no statistical difference in the 5-HTT gene polymorphism between patients and controls, and according to the subtypes of IBS patients (p=0.135). CONCLUSIONS: There was no relationship between serotonin transporter gene polymorphism and IBS. However, allele S/S genotype was most prominent genotype in both controls and patients.