CD7(Cluster of Differentiation 7) is a human protein encoded by the CD7 gene. This gene encodes a transmembrane protein which is a member of the immunoglobulin superfamily. This protein is found on thymocytes and mature T cells. It plays an essential role in T-cell interactions and also in T-cell/B-cell interaction during early lymphoid development. CD7 has been shown to interact with PIK3R1. This protein can be aberrantly expressed in refractory anaemia with excess blasts (RAEB) and may confer a worse prognosis.