{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"T cell receptor delta locus (symbol TRD), also known as TCRD, is a protein that in humans is encoded by the TRD gene. It contributes the delta (δ) chain to the larger TCR protein (T-cell receptor). The T cell receptor or TCR is a molecule found on the surface of T lymphocytes (or T cells) that is responsible for recognizing antigens bound to major histocompatibility complex (MHC) molecules. The TCR is composed of two different protein chains (that is, it is a heterodimer). In 95% of T cells, this consists of an alpha (α) and beta (β) chain, whereas in 5% of T cells this consists of gamma and delta (γ/δ) chains."}]},{"type":"paragraph","children":[{"type":"text","value":"Deletions and mutations of the TRG and TRD gene have been implicated in a variety of cancers. Specifically, γδ T cells may contribute to the immune response against several tumor types (lymphoma, myeloma, breast, colon, lung, ovary, and others). They act directly through mediation of cytotoxic activity and indirectly through the regulation of other cell types responsible for the anti-tumor response. The presence of γδ T cells in the tumor microenvironment has been associated with poor prognosis in some cancers. While γδ T cells have been implicated in T cell lymphomas, there is also a specific subtype known as γδ T-cell lymphoma, characterized by the proliferation of those cells exclusively. This lymphoma can be quite aggressive with ulcerative plaques and subcutaneous nodules. In adenocarcinoma, polyclonal rearrangement of the TCR γ chain gene was significantly greater in N1 and N2 patients (using the TNM cancer staging system) than in N0 patients. Apart from carcinomas, TRG has also been correlated with hepatitis B virus (HBV). Specifically, Vδ2+ T cell levels and TCR γδ T cell cytotoxicity were significantly lower in patients with chronic HBV infections."}]}]}