G protein β3 subunit, interleukin-10, and tumor necrosis factor-α gene polymorphisms in Koreans with irritable bowel syndrome

Background: The association between irritable bowel syndrome (IBS) based on Rome III criteria and G protein β3 subunit (GNB3), interleukin (IL)-10, and tumor necrosis factor (TNF)-α gene polymorphisms is uncertain. Methods: Case and control subjects were recruited from Korean visitors to the Health Promotion Center and Digestive Disease Center for gastrointestinal endoscopy. G protein β3 subunit, IL-10, and TNF-α gene polymorphisms were genotyped using a polymerase chain reaction-based method. Multifactor dimensionality reduction (MDR) analysis was used to assess gene-gene interactions. Key Results: Genotype and allele frequencies of GNB3 showed marginal significance between the healthy controls and IBS patients (χ² = 5.92, P = 0.052; χ² = 3.76, P = 0.053). G protein β3 subunit T allele was more strongly correlated with IBS with constipation (12 of constipation-dominant type and 31 of mixed type) than with 51 diarrhea-dominant type and 88 normal subjects (χ² = 13.91, P = 0.008). Multifactor dimensionality reduction analysis revealed that there were no significant interactions of GNB3, IL-10, and TNF-α gene variants with susceptibility to IBS (P > 0.05). Conclusions & Inferences: The results suggest that GNB3 825T allele might be associated with IBS with constipation in Koreans.