A review of the JR blood group system

The JR blood group system (ISBT 032) consists of one antigen, Jr^a, 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-Jr^ahas caused transfusion reactions and is involved in hemolytic disease of the fetus and newborn. The Jr^aantigen is located on ABCG2 transporter, a multipass membrane glycoprotein (also known as the breast cancer resistance protein, BCRP), which is encoded by the ABCG2gene on chromosome 4q22.1. The Jr(a–) phenotype mostly results from recessive inheritance of ABCG2null alleles caused by frameshift or nonsense changes. Immunohematology2013;29:63–68.