A study of candidate genotypes associated with dyspepsia in a US community

BACKGROUND: The role of genetic predisposition to the development of dyspepsia is unclear. Recently, a significant association was reported with CC genotype of GN beta 3. AIM: To explore the association of candidate genotypes altering adrenergic, serotonergic, CCKergic, and G protein functions, and dyspepsia in a sample from a U.S. community. METHODS: Dyspeptics and healthy controls were identified among community respondents who had been randomly selected to complete validated questionnaires. Other diseases were excluded by face-to-face history and physical examination. Polymorphisms of candidate genes for alpha(2A), alpha(2C), 5-HT1A, 5-HT2A, 5-HT2C, CCK-1 receptors and CCK promoter, GN beta 3 protein, and SERT-promoter (SERT-P) were studied. The association between polymorphisms and meal-related or meal-unrelated dyspepsia, high somatic symptom scores, and somatization were evaluated using Fisher's exact test. RESULTS: DNA was available from 41 dyspeptics and 47 healthy controls from Olmsted County. Community dyspepsia unrelated to meals was associated with both homozygous GN beta 3 protein 825T and C alleles. There were no significant associations with meal-related dyspepsia. Using Rome II subgroups, the same genotype was associated with dysmotility-like and other dyspepsia. Higher somatization scores were not significantly associated with any of the candidate genes when considered as single factors. CONCLUSION: Meal-unrelated dyspepsia in a U.S. community study is associated with the homozygous 825T or C alleles of GN beta 3 protein. Candidate genes controlling adrenergic, serotonergic, and CCKergic functions do not appear to be associated with dyspepsia.