The Multivariate Analysis Of The Relationship Between G Protein β₃ Subunit Gene C825T Polymorphism And Essential Hypertension

PrefaceAt present, the cardiovascular and cerebrovascular diseases have been one of the most important causes of human death. As the common risk factor of the cardiovascular and cerebrovascular diseases, Essential Hypertension ( EHT) has been paid generally attention. However, people know little about EHT. It is necessary to research the causes of this disease deeply. So that, we could control the prevalence rate of EHT in order to prevent the incidence of the cardiovascular and cerebrovascular diseases.Heretofore, a good many results of investigation hint: EHT results from the effect of environmental and genetic factors. In 1998, G - Protein β₃ - Subunit Gene (GNB₃ gene) was confirmed by American Hypertension Journal as one of the correlative genes of Hypertension. Now, the relationship between GNB₃ gene 825C/T SNP ( single nucleotide polymorphisms) and EHT has not been confirmed. And the recent research was mostly limited to the aspect of analyzing the relationship between the polymorphism and EHT simply, without considering the effect of other factors. The research will start with the genetics and epidemiology, and then analyzing the relationship between GNB₃ gene 825C/T SNP and EHT based on considering the multivariate function.Subjects and Methods1. The selection of subjectsTwo villages were randomly selected in Zhangwu County, Liaoning Province. All the people above 30 years old were investigated. 136 cases (male/fe-male: 41/95, mean age;47. 56 ± 10. 87) with hypertension were selected as case group, and secondary hypertension was excluded. 197 matched control subjects (male/female;77/120, mean age: 47.24 ±12.08) without hypertension was selected from the same population.2. Diagnosis standard and the methods of measurementsThe diagnosis standard of EHT;According to 1999 WHO - ISH guidelines for the management of hypertension, hypertension was defined as a systolic blood pressure ( SBP) ^ 140mmHg and/or a diastolic blood pressure ( DBP) ^ 90mmHg. The measurement of blood pressure should be carried out according to the unified standard under standard conditions.3. The contents of epidemiological surveyQuestionnaires were filled by means of inquiring and measurement in sites. The contents of survey included: general characteristics, alcohol intake, smoking habits, family history of hypertension and other disease history and so on, and measuring of the blood pressure, body height and weight. Five milliliters blood samples were drawn after an overnight fast. After centrifugation, the serum fraction was removed. Then, six milliliters blood samples were drawn without centrifugation. All the blood samples were frozen at -20T! until assayed.4. The index and methods of detecting indicatorsThe GNB3 gene 825C/T SNP was detected by PCR - RFLP. The primers were provided by Shanghai Shenggong bioengineering Ltd. The expression of 825T was detected by GDS8000 system. Cholesterol, triglyceride, high density lipoprotein (HDL) , low density lipoprotein ( LDL) , serum sodium, serum potassium, serum iron, serum calcium were measured by automatic biochemistry analyzer 7150 (HITACHI, Japan) , the blood sugar was measured by blood sugar analyzer (Johnson & Johnson, America).5. Statistical methodsThe software used was SPSS11. 5. Student's t - test was used to assess differences between groups for two continuous variables. Statistical analysis of dichotomous variables was by the chi - square test. Multiple logistic regression was used when evaluating the effect of continuous or categorical covariates on a dichotomous outcome. A 2 - sided value of a =0.05 was regarded as statistical-ly significant.Results1. The distribution of age and gender between case group and control group Female are more than male. The proportion of female in case group is morethan it in control group. The average age of the subjects is about 47. There was no statistical difference of age, sex(p > 0. 05) between case group arid control group.2. The distribution of GNB3 gene 825 nucleotide in the subjects2.1 The distribution of GNB3 gene 825 nucleotide in case group and control group2.1.1 The compare of CC, CT and TT genotype in case group and control groupThere are two alleles of GNB3 gene 825 nucleotide: C and T. They form three genotypes;CC, CT and TT. The largest proportion of genotype is CT.and the frequency of this allele is 50.5%. There was no statistical difference of genotypes (p >0. 05) between case group and control group.2.1. 2 The compare of CC and( CT/TT) genotype between case group and control groupThe frequency of (CT/TT) genotype are more than it of CC genotype. The frequency of people with T allele is 74. 5%. There was no statistical difference of gene expression of T allele (p >0. 05) between case group and control group.2. 1.3 The compare of C and T allele between case group and control groupThere was no statistical difference of gene frequency of C and T allele (p > 0.05) between case group and control group. The frequency of T allele is 49. 2% .2.2 The distribution of GNB3 gene 825 nucleotide in different age group The frequency of(CT/TT) genotype are more than it of CC genotype in different age group. There was no statistical difference of the frequency of people with T allele ( p > 0. 05 ) in different age group between case group and control group.2. 3 The distribution of GNB3 gene in different gender group2. 3 The distribution of GNB3 gene in different gender groupThe frequency of ( CT/TT) genotype of male are more than it of CC genotype in different gender group. There was no statistical difference of the frequency of people with T allele (p > 0. 05) in different gender group between case group and control group.3. Monovariate analysis on the related risk factors concerned with hypertensionThe analysis showed that there was no significant statistical difference in the distribution of GNB3 gene 825 nucleotide genotype between case group and control group(P >0.05, OR = 1. 279,95% C. 1:0. 769 2. 127). Compared with low level of blood sugar, high level of blood sugar was a risk factor of EHT( OR= 13. 000,95% C. 1:2. 937 57.536). Compared with low level of cholesterol, high level of cholesterol was a risk factor of EHT( OR = 2.014,95% C. 1:1.286 3. 174). Alcohol intake was a protective factor of EHT( OR = 0.540,95% C. 1:0.315-0.925).4. Multivariate analysis concerned with hypertensionMultivariate analysis was conducted on the factors which had statistical significance of less than 0. 1 compared with control group in monovatiate analysis. Using stepwise logistic regression analysis constitute model of EHT. GNB3 gene 825 nucleotide genotype can not enter the model. The model showed that compared with low level of blood sugar, high level of blood sugar was a risk factor of EHT( OR = 12. 701,95% C. 1:2. 854 56. 525). Alcohol intake was a protective factor of EHT( OR =0.544,95% C. I:0.312 ⁰.948).DiscussionGNB3 gene was recognized as the correlative gene of hypertension in 1998. It is a new correlative gene. There were a fat lot report of the relationship between GNB3 gene 825C/T SNP and EHT. Moreover, most of them are analyzing the relationship between the SNP and EHT simply, without considering the effect of other factors.This research showed that the frequency of GNB3 gene 8 2 5 T allele is49.2% , which is in the average level in Asia. Moreover, there was no statistical difference of gene expression of T allele (p > 0. 05) between different age group and different gender group. Using EHT as dependent variable, GNB3 gene 825 nucleotide genotype and other risk factors as independent variables, the model showed that GNB3 gene 825 C/T SNP can not enter the model after multi-variate analysis. Only blood sugar and alcohol intake enter the model.G proteins are key components of intracellular signal transduction, and they can enhance the ion exchangers'activity. They take part in a lot of intracellular effect with the activity of blood vessel and increment. The mechanism of the relationship between the 825T genotype and EHT hasnt been made clear. It maybe relates with enhancing the activity of G proteins. This research hasnt found the relativity between GNB3 gene 825C/T SNP and EHT. However, it can still be used as a reference in future.ConclusionsAfter multivariate analysis of the environmental and genetic factors, the outcome hints, that GNB3 gene 825C/T SNP might not be a risk factor of EHT. There was no statistical difference between them.