Tumor necrosis factor a (TNF-alpha) is a proinflammatory cytokine that is produced by activated macrophages. It has been shown to stimulate the release of endothelial cytokines and NO, increase vascular permeability, decrease contractility, and induce a prothrombotic state. The most studied TNF-a gene mutation in heart disease is a gamma to alpha substitution, which occurs when 308 nucleotides move upstream from the transcription initiation site in the TNF promoter and has been associated with elevated levels of TNF-alpha. The TNF1 allele (wild type) contains gamma at this site, while the TNF2 allele has an alpha substitution at the site. The TNF2 allele is a more powerful transcriptional activator, therefore leading to higher TNF-alpha levels. Most of the studies to date have failed to conclusively show any link between the polymorphism and heart disease, both coronary artery disease and cardiomyopathy/heart failure.