BACKGROUND: The prevalences of hypertension, cerebrovascular diseases, etc. are higher in Mongolian population because of the influence of various factors including genetics, geography, diet, etc. Therefore, it is helpful for prevention to develop researches on the genetics of various diseases including hypertension in Mongolian population.OBJECTIVE: To analyze the association between C825T polymorphisms of G-protein beta 3 subunit gene (GNB3), the important candidate gene of various disease of cardiovascular system, and Mongolian patients with essential hypertension.DESIGN: A comparative observation.SETTINGS: Department of Neurology, the First Affiliated Hospital of Inner Mongolia Medical College;Wulate Houqi Red Cross Society.PARTICIPANTS: Totally 267 Mongolian residents, whose blood relations of 3 generations were all Mongolians, were selected from Wulate Houqi, Inner Mongolia. The patients were screened based on the diagnostic standard of hypertension set by WHO in 1999, and the enrolled subjects were divided into two groups according to the level of blood pressure: ① Normal blood pressure group (n =124): 64 males and 60 females, systolic blood pressure (SBP) ＜ 140 mm Hg (1 mm Hg=0.133 kPa), diastolic blood pressure (DBP) ＜90 mm Hg; ② Essential hypertension group (n =143): 71 males and 72 females, including 60 patients with simple high SBP (SBP ranged 145 to 195 mm Hg, whereas DBP ＜ 90 mm Hg).METHODS: Peripheral venous blood (5 mL) was drawn from all the subjects, the genome DNA was extracted, and the polymorphisms of the GNB3 C825T genotype were detected with the Sequenom system.Polymerase chain reaction (PCR) experiment and SNP detection were performed in Beijing Huada gene laboratory. Then the univariate analysis of variance was applied in the sample comparison among groups, and the chi-square test was used to compare the genotypes and allele frequencies. The odd ratio (OR) and 95% confidence interval (CI)were calculated.MAIN OUTCOME MEASURES: The distributions of GNB3 C825T genotypes and alleles were observed.RESULTS: All the 267 Mongolian subjects were involved in the analysis of results. ① GNB3 C825T genotypes: In Mongolian population, the frequencies of CC, CT and TT genotypes at GNB3 C825T site in the essential hypertension group (48%, 41%, 11%) were not obvious different from those in the normal blood pressure group (43%, 47%, 10%, x2 =0.162, P =0.688; OR:1.176, 95%CI: 0.533- 2.592), whereas there were also no obvious differences between the simple high SBP group (57%, 35%, 8%) and the normal blood pressure group (x2 =0.733, P =0.392; OR:1.957, 95%CI: 0.623- 6.143). ② GNB3 C825T alleles: In Mongolian population, The frequencies of C and T alleles in the essential hypertension group (69%, 31%)were not obviously different from those in the normal blood pressure group (67%, 33%, x2 =0.094, P =0.759; OR:0.945, 95%CI: 0.657 - 1.358), whereas there were also no obvious differences between the simple high SBP group (74%, 26%) and the normal blood pressure group ( x2=2.133, P =0.144; OR:0.697, 95%CI:0.428 - 1.133).CONCLUSION: GNB3 C825T site may be not a genetic marker of essential hypertension and simple high SBP in Mongolian population.