The JR blood group system (ISBT 032) consists of one antigen, Jra, which is of high prevalence in all populations. The rare Jr(a–) phenotype has been found mostly in Japanese and other Asian populations, but also in people of northern European ancestry, in Bedouin Arabs, and in one Mexican. Anti-Jrahas caused transfusion reactions and is involved in hemolytic disease of the fetus and newborn. The Jraantigen is located on ABCG2 transporter, a multipass membrane glycoprotein (also known as the breast cancer resistance protein, BCRP), which is encoded by the