RHD (gene)

Rh blood group, D antigen also known as Rh polypeptide 1 (RhPI) or cluster of differentiation 240D (CD240D) is a protein that in humans is encoded by the RHD gene.

The RHD gene codes for the RhD erythrocyte membrane protein that is the Rh factor antigen of the Rh blood group system. RHD has sequence similarity to RHCE, RhAG, RhBG, and RhCG and these five genes constitute the Rh family. It was proposed that the erythrocyte Rh complex is a heterotrimer of RhAG, RhD, and RhCE protein subunits. RhAG is a functional ammonia transporter and is required for normal cell surface expression of RhD and RhCE. Patients who lack RhD/RhCE/RhAG on the surface of their erythrocytes have hemolytic anemia. Antibodies to the RhD protein can cause Rh disease.