CPT® Code 81342

TRG@ (T cell antigen receptor, gamma) (eg, leukemia and lymphoma), gene rearrangement analysis, evaluation to detect abnormal clonal population(s)

The CPT® Code 81342 pertains to the molecular genetic testing of the T cell antigen receptor, gamma (TRG@) gene, which is located on chromosome 7. This test is specifically designed to analyze gene rearrangements that may indicate the presence of abnormal clonal populations, which are often associated with certain types of leukemia and lymphoma. T cell antigen receptors play a crucial role in the immune system, as they are responsible for recognizing foreign antigens—small peptide fragments that are presented by major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells (APCs). The structure of T cell antigen receptors is similar to that of immunoglobulin genes and is composed of various gene segments that come together to form functional receptors. The T cell antigen receptor is primarily made up of alpha/beta chains (approximately 95%) and gamma/delta chains (about 5%). The focus of this test is on the gamma T cell antigen receptor, which is a smaller subset of T cell receptors predominantly found in intraepithelial lymphocytes within the gut and, to a lesser extent, in the skin. The gamma subunits of these receptors contain variable (V) regions that are crucial for defining the characteristics of the T cells. The testing process typically employs non-radioactive polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) techniques, along with histological and immunophenotypic analyses, to effectively detect any abnormal clonal populations. This comprehensive gene expression analysis is instrumental in evaluating the immune response related to various conditions, particularly those affecting blood cells and the lymphatic system, including cancers.