CD3G gene encodes CD3-gamma polypeptide, which together with CD3-epsilon, -delta, and -zeta, and the TCR alpha/beta and gamma/delta heterodimers, forms the TCR-CD3 complex. This complex plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways. The CD3 gamma chain has long been considered to mediate targeting to lysosomes for degradation. Defects in this gene are associated with T cell immunodeficiency. Further, it has been proposed as one of the important candidate genes for cancer development due to its pivotal roles in TCR signaling pathway.