Lymphotoxin Alpha (LTA), formerly known as Tumor Necrosis Factor Beta (TNFB), is a cytokine secreted by activated lymphocytes, which plays an important role in cell proliferation and differentiation, apoptosis, coagulation, neurotransmission, and development of secondary lymphoid organs. LTA mediates its effects in a homotrimeric or a heterotrimeric form with one or two LTB subunits. The homotrimeric form is secreted by the lymphocytes, and the ligand binds to TNFR1, thereby effecting further downstream reactions. The heterotrimeric form, on the other hand, contains LTB, which anchors the protein complex to the cell surface, and influences further downstream signaling cascades.

LTA polymorphisms have been implicated in the pathogenesis of atherosclerosis as well as coronary heart disease. In addition, a wide variety of tumor cells have been shown to secrete LTA.

The LTA gene, covering about 2 Kb of DNA, maps to the short arm of chromosome 6. The LTA protein, weighing about 22.3 KDa, consists of 205 amino acids. One of the most important polymorphisms in the LTA gene is the A252G SNP in intron 1, which has been reported to significantly influence the level of the LTA transcript. Certain SNPs in the gene have also been noticed in patients with myocardial infarction, suggesting a role for LTA in granting susceptibility to this disorder.