G-protein β3 subunit 825CC genotype is associated with postprandial distress syndrome with impaired gastric emptying and with the feeling of hunger in Japanese

Background G-protein dysfunction related alteration of intracellular signal transduction might be linked to various abnormalities of functional gastrointestinal (GI) disorders. Serotonin (5-hydroxytryptamine; 5-HT) as well as G-protein is also key signaling molecule sensorimotor functions in the GI tract. Thus, this study aims to evaluate the correlation between gastric emptying and GN beta 3 and 5-HTs polymorphisms in functional dyspepsia (FD) as defined by Rome III classification. Methods Seventy-four patients presenting with typical symptoms of FD (epigastric pain syndrome: EPS, n = 24; postprandial distress syndrome: PDS, n = 51) and sixty-four healthy volunteers were enrolled. Gastric motility was evaluated with the T-max value using the C-13-acetate breath test. We used Rome III criteria to evaluate upper abdominal symptoms and SRQ-D scores to determine depression status. GN beta 3-C825T, 5-HT1A-C1019G, 5-HT2A-G1438A, 5-HT3A-C42T, and 5-HT4A-G353 + 6A polymorphisms were analyzed in DNA from blood samples of enrolled subjects. Genotyping was performed by polymerase chain reaction. Key Results There was a significant relationship (P = 0.045) between GN alpha 3 825CC genotype and PDS patients without gastro-esophageal reflux symptoms with impaired gastric emptying. In Japanese, GN beta 3 825CC genotype in FD patients was significantly associated (P = 0.0485) with the feeling of hunger compared with GN beta 3 825CT and TT genotypes. Conclusions & Inferences Our results suggest that the GN beta 3 825CC genotype is significantly associated with PDS patients without gastro-esophageal reflux with impairments of gastric emptying and also with the feeling of hunger in patients with FD. Further studies are needed to clarify whether the GN beta 3 825CC genotype is linked to disturbances of gastric emptying via altered signal transduction responses.