Molecular genetics as the route to understanding, prevention, and treatment

Determination of single-nucleotide polymorphism in the proximal promoter region of apolipoprotein M gene in coronary artery diseases

OBJECTIVE

It has been reported that single-nucleotide polymorphism (SNP) in the proximal promoter region of apolipoprotein M (apoM) gene may confer the risk in the development of type 2 diabetes (T2D) and coronary artery disease (CAD) in the Han Chinese. However, in a recent study demonstrated that plasma apoM level did not correlated to the coronary heart disease. In the present studies, we investigated the SNP T-778C of apoM gene in CAD patients and controls in the Han Chinese population. Moreover we examined whether serum apoM levels could be influenced by this promoter mutation.

MATERIAL AND METHODS

One hundred twenty-six CAD patients and 118 non-CAD patients were subjected in the present study. All patients were confirmed by the angiography. The genotyping of polymorphisms T-778C in apoM promoter was determined by real-time polymerase chain reaction. Serum apoM levels were semi-quantitatively determined by the dot-blotting analysis.

RESULTS

Distribution of apoM T-778C genotype in non-CAD patients was as following: 84.7% were T/T, 15.3% were T/C and 0.0% was C/C. T allele frequencies were 92.4% and C allele, 7.6%. In the CAD patients, 99 patients (78.6%) had the T/T genotype, 25 patients (19.8%) with T/C genotype and 2 patients (1.6%) with C/C genotype. The allele frequency was 88.5% for the T allele and 11.5% for the C allele. There was no statistical significant difference of serum apoM levels found in these three genotypes.

CONCLUSIONS

There was no significant difference in allele or genotype frequencies between CAD patients and non-CAD patients. Binary logistic regression analysis with adjustments for age, gender, triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein, apoAI, apoB, and LP(a) indicated that the TC and CC genotypes in SNP T-778C were not significantly associated with the development of CAD (odds ratio = 1.510, 95% confidence interval: 0.756-3.017; p = 0.243).

Polymorphisms in the TNF-alpha and TNF-receptor genes in patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is both multifactorial and polygenic in nature. Atheroma formation, the pathological hallmark of CAD, is an inflammatory process, with pro-inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha), having a major role in its pathogenesis. We have therefore investigated whether polymorphisms in the TNF-alpha (- 238 and - 308), TNF receptor 1 (position - 609 and + 10, intron 6) and TNF receptor 2 (position + 422, codon 198) genes show an association with CAD.

MATERIALS AND METHODS

Patients with angiographically proven single vessel (n = 58) and multivessel (n = 122) CAD were compared to patients with angiographically proven normal coronary arteries (n = 79) and volunteers without clinical evidence of CAD (n = 250). Genotyping was performed by PCR-RFLP analysis. For the TNF-alpha polymorphisms, a meta-analysis of all published studies was also undertaken.

RESULTS

No significant differences in allele or genotype frequencies were found between the normal coronary artery group or healthy volunteers and patients with CAD for any of the polymorphisms. There was also no difference in allele frequency between patients with single- and multivessel disease. For the - 308 and - 238 TNRalpha gene polymorphisms, a meta-analysis of our data and previously published studies failed to demonstrate any significant association with CAD.

CONCLUSIONS

Polymorphisms in the TNF-alpha promoter region and TNF-receptor genes are not associated with the development of CAD.

[Genetic risk factors for myocardial infarct]

Interactions of genetic and environmental risk factors influence the susceptibility to coronary artery disease (CAD) and myocardial infarction. In myocardial infarction occurring at young age, genetics of this multifactorial disease may be the leading factor. A number of candidate genes have been implicated in the pathogenesis of CAD and myocardial infarction. Mutations in the DNA sequence (gene polymorphisms) have been identified that appear to play a crucial role in blood pressure regulation, lipid metabolism, endothelial function, in the pathophysiology of coagulation or thrombosis, or in interventional cardiology by interfering with restenosis development. Genetic polymorphisms seem to be clinically important because they not only potentiate the individual risk under certain circumstances, but they also determine safety and effectiveness of commonly prescribed drugs. Understanding the complexity and functional relevance of genetic risk factors will be useful in early detection and treatment of individuals that are exposed to higher risk for myocardial infarction. Thus it is important to include genetic risk factors in the concept of the classical risk factor theory. Potentially in future a genetic risk profile including relevant polymorphisms may be an essential part of the clinicians' knowledge in primary and secondary prevention of coronary artery disease.

Changes in serum total cholesterol levels over 18 years in a cohort of men and women: The Nijmegen Cohort Study

BACKGROUND

This study aimed to investigate to what extent cholesterol levels change in individuals in different age groups over an 18-year period. Factors that contribute to the changes, with respect to prevention of cardiovascular disease, were taken into account.

METHODS

In 1977 serum cholesterol, systolic and diastolic blood pressures, body mass index, and smoking habits were measured in a cohort of 7,092 patients (men and women from 20 to 50 years of age) from six general practices in The Netherlands. In 1995, a sample of 2,600 of these same patients were invited to take part in a similar screening program; 2,335 patients, consisting of 1,171 men and 1,164 women, agreed to participate. Patients were derived from both high-risk and low- to normal-risk category in 1977. The differences in cholesterol between 1977 and 1995 were calculated and cholesterol levels were tracked over the study period by determining Pearson correlation coefficients. A multiple linear regression analysis was performed to investigate the determinants influencing the changes in cholesterol level.

RESULTS

The mean cholesterol levels rose during the study period in all age groups. The highest mean increase in men was 1.23 mmol/L, or 20%, in the youngest age group (20-24 years), and in women the maximum mean increase was 1.12 mmol/L, or 17%, in the age group 40-44 years. Correlation coefficients between the 1977 and 1995 readings varied from 0.63 in the youngest age group to 0.41 in the oldest. Body weight change during the study period, more than initial body weight, was found to have influenced the rise in serum cholesterol. At basic screening, 19.2% of the men and 12.4% of the women had cholesterol levels of 6. 5 mmol/L or higher, as against 35.8 and 36.8%, respectively, in 1995.

CONCLUSIONS

Over an 18-year period cholesterol level increased in most subjects, at a younger age in men than in women. The highest increase in women took place during the menopausal period. Weight gain, more than baseline weight, had a positive influence on the increase in cholesterol.