TCR is expressed on the surface of T cell and recognizes diverse antigens such as proteins, polysaccharides, bacteria or viruses. Usually, the TCR gene includes an ?-chain and a ?-chain, the former consists of variable (V), joining (J) and constant (C) gene fragments, while the TCR ?-chain is made up of a V, J and C region, with an additional diversity (D) region and these genes can be grouped into a distinct TCR V? gene family. What’s more, the rearrangement of those TCR genes plays a crucial role in antigen recognition by T cells, which enables T cells to recognize antigens specifically, and any dysregulation in this complex yet highly regulated process may lead to disease.