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 to develop researches on the genetics of various diseases including hypertension in Mongolian population.OBJECTIVE: To analyze the association between the polymorphism of beta1 adrenergic receptor (β1-AR)gene G1165C (Arg389Gly), an important candidate gene for various diseases of cardiovascular system, and essential hypertension in Mongolian population.DESIGN: A cross-sectional study.SETTINGS: Department of Neurology, the First Affiliated Hospital of Inner Mongolia Medical College; Wulate Houqi Red Cross Society.PARTICIPANTS: The survey was carried out from February 2003 to March 2005. Totally 239 Mongolian residents, whose blood relations of 3 generations were all Mongolians, were selected from Wulate Houqi, Inner Mongolia, and they were all informed with the survey and detected items. Based on the diagnostic standard of hypertension set by WHO in 1999, the subjects were divided into two groups according to the level blood pressure: ① Normal blood pressure group (n=117): systolic blood pressure (SBP) ＜ 140 mm Hg (1 mm Hg =0.133 kPa), diastolic blood pressure (DBP) ＜ 90 mm Hg, and those having histories of cerebrovascular disease, heart disease, diseases of liver, kidney and tiroides, and diabetes mellitus were excluded. ② Essential hypertension group (n=122): including 51 patients with simple high SBP. All the enrolled subjects had no blood relationship with each other, and had no history of miscegenation.METHODS: The body height, body mass, waist circumference and blood lipids were measured routinely, and their habits of smoking and drinking were also investigated. Peripheral venous blood (5 mL) was drawn, the genome DNA was extracted, and the polymorphisms of the β1-AR G1165C (Gly389Arg) genotype were detected with the Sequenom system. Polymerase chain reaction (PCR) experiment and SNP detection were performed in Huada Gene Laboratory of Bejing, 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 (Cl) were calculated.MAIN OUTCOME MEASURES: The distributions of β1-AR G1165C (Gly389Arg) genotypes and alleles were observed.RESULTS: All the 239 subjects were involved in the analysis of results, and no one missed. ① Comparison of β1-AR G1165C (Gly389Arg) genotypes and allele distributions: In Mongolian population, the frequencies of CC and GG+GC genotypes at β1-AR G1165C (Gly389Arg) site in the essential hypertension group (72%, 28%) were not significantly different from those in the normal blood pressure group (67%, 33%)(x2=0.841, P=0.359; O~ 0.773, 95%Cl: 0.445-1.342); The frequencies of C and G alleles also had no significant differences between the essential hypertension group (85%, 15%) and the normal blood pressure group (82％, 18％) (~=1.136, P=-0.287; O~: 0.769, 95％Cl: 0.747-1.248). ②The frequencies of CC and GG+GC genotypes at β1-AR G1165C (Gly389Arg) site had no significant differences between the patients with simple high SBP (71%, 29%) and the normal blood pressure group (x2=0.250, P=-0.617; OR:. 0.833,95%Cl: 0.408-1.703); The frequencies of C and G alleles were not significantly different between the patients with simple high SBP (86%, 14%) and the normal blood pressure group (x2=0.670, P=0.413; OR:.0.766, 95%Cl: 0.404-1.453).CONCLUSION: In Mongolian population, the distributions of the genotypes and alleles of β1-AR G1165C (Gly389Arg) have no obvious differences between the subjects with normal blood pressure and the patients with essential hypertension (including simple SBP increase), which suggests that G1165C (Glu389Asp) site of β1-AR gene may be not a genetic mark of essential hypertension and simple high SBP in Mongolian population.