The association of SLC6A4 5-HTTLPR and TRPV1 945G>C with functional dyspepsia in Korea

Background and Aim: The association of various genetic polymorphisms with functional dyspepsia (FD) has been suggested, but the results were still controversial. The aim of the present study was to assess the association of GNB3 825C>T, SLC6A4 5-HTTLPR, ADRA2A-1291C>G, CCK-1R intron 779T>C, and TRPV1 945G>C polymorphisms with FD based on Rome III criteria in Korea. Methods: Study subjects were prospectively recruited from visitors to Seoul National University Bundang Hospital between 2009 and 2012. One hundred and twelve FD patients and 269 controls were enrolled. Results: In SLC6A4 5-HTTLPR polymorphism, the frequency of S/S genotype was significantly lower than that of L/L+L/S genotype in FD compared to controls (P<0.05). After stratification according to Helicobacter pylori infection, the S/S genotype was significantly associated with H.pylori-positive epigastric pain syndrome (EPS) patients (adjusted odds ratio (OR) 0.46; 95% confidence interval (CI) 0.22-0.99; P = 0.048). In TRPV1 945G>C polymorphism, the frequency of C/C genotype was lower in FD compared to controls (P = 0.057). The C carrier and C/C genotype was significantly associated with postprandial distress syndrome (PDS) and EPS, respectively (adjusted OR 0.47 and 0.43; 95% CI 0.25-0.90 and 0.20-0.93; P = 0.021 and 0.033). After stratification, the significant associations remained in H.pylori-positive PDS and EPS patients (adjusted OR 0.37 and 0.28; 95% CI 0.16-0.88 and 0.09-0.85; P = 0.024 and 0.025). Conclusions: The genetic polymorphism of SLC6A4 5-HTTLPR and TRPV1 945G>C could be one of the pathophysiological factors of FD, especially in the case of H.pylori-positive patients in Korea.