Biological and Clinical Implications of TNF-α Promoter and CYP1B1 Gene Variations in Coronary Artery Disease Susceptibility.

Background: Cardiovascular diseases (CVD) are important causes of death worldwide. Atherosclerosis is a chronic inflammatory disorder. It is the major cause of CVD and is manifested by ischemic heart disease or coronary artery disease (CAD). TNF-α is a pro-inflammatory cytokine that regulates immune response and promotes the development of atherosclerosis. Cytochrome p450 1B1 (CYP1B1) is an enzyme involved in the metabolism of endogenous and exogenous substrates.

Objectives: This study aimed at examining the association of TNF-α rs1800629 G>A and CYP1B1 rs1056827 G>T gene polymorphisms with CAD susceptibility in an Indian cohort.

Methods: AS-PCR and direct DNA sequencing were used to examine the association of TNF-α rs1800629 G >A and CYP1B1 rs1056827 G>T gene polymorphism with CAD in an Indian cohort. A total of 100 clinically confirmed cases of CAD and 110 matched apparently healthy controls were genotyped.

Results: Allelic and genotypic frequencies did not deviate from Hardy-Weinberg equilibrium in the controls (p>0.05) for TNF-α G-308A and CYP1B1 rs1056827G>A. There was no significant difference between the TNF-α rs1800629 A>G genotype distribution between cases and controls (P-value >0.05). A significant difference was observed between the CYP1B1 rs1056827 G>T genotype distribution between CAD cases and controls (p<0.0003). Our result indicated that in the codominant model, the GA genotype of the CYP1B1 rs1056827 G>T was associated with CAD with OR= 2.21(1.17 to 4.15), RR=1.38(1.07 to 1.78), and p<0.013. In the dominant model, the (GA+AA) genotype was associated with CAD with OR=2.79(1.54 to 5.05) and p<0.007. The CYP1B1 rs1056827 'A' allele was associated with CAD with OR = 2.30 (1.55 to 3.42) and p< 0.0001. Our results indicated that TNF-α 1800629 gene polymorphism was strongly associated with hypercholesteremia (p<0.0009), HDL (p<0.0001), TGL (p<0.039), hypertension (p<0.0001), and smoking (p<0.0001) in patients with Coronary Artery Disease. Similar correlations of CYP1B1 rs1056827 genotypes were reported with cholesterol (p<0.020), HDL (p<0.002), LDL (p<0.006), hypertension (p<0.03), and smoking (p<0.005).

Conclusion: It was reported that the GA genotype of the CYP1B1 rs1056827 G>T was strongly associated with susceptibility to Coronary Artery Disease with OR= 2.21(1.17 to 4.15)) and p<0.013, and similarly, its A allele was associated with predisposition to CAD with OR = 2.30 (1.55 to 3.42) and p< 0.0001. Our results indicated that TNF-α 1800629 gene polymorphism is not associated with predisposition to Coronary Artery Disease. Nevertheless, these results should be taken with caution and further validated with larger-scale studies before being introduced in the clinical setting.