Advance in the Rh blood group system.
The Rh blood group antigens are associated with non-glycosylated red blood cell membrane proteins encoded by two closely related genes, RHD and RHCE. Both RH genes have 10 exons and the open reading frames of their transcripts are composed of 1251 nucleotides. The sequence analyses of RHCE transcripts revealed that RhC/c and RhE/e are related to six nucleotide substitutions and a single substitution, respectively. Molecular analyses have elucidated the genetic background of various RhD and RhCE variants including the Rhnull phenotype with neither RhD nor RhCE antigen. The Rh polypeptides require some co-molecules for their assembly in the plasma membranes. In fact, several unrelated proteins other than those of the Rh polypeptides are reduced or absent on Rhnull red blood cells. This group includes the Rh50 glycoprotein, LW glycoprotein, glycophorin B, Duffy glycoprotein, and CD47 glycoprotein. The mutation of the RH50 gene is inducible of the Rhnull phenotypes. Although the Rh50 glycoprotein is a critical co-expressing factor, one or more factors seem to be required to express RhD or RhC(c)E(e) antigens on the plasma membranes. Additionally, polymerase chain reaction-based tests for Rh genotyping were developed and some have been put in practice. Much information obtained from the molecular approach to the Rh blood group system has shed considerable light on the Rh polypeptides. In the near future, the mechanism of expression, the function, and the evolution of Rh polypeptides will be clarified further.
Kajii
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Department of Legal Medicine & Human Genetics, Jichi Medical School, Tochigi-ken, Japan.
D000744:Anemia, Hemolytic, Autoimmune / Q000276:immunology; D001324:Autoantigens; D004910:Erythrocyte Membrane / Q000276:immunology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction; D012204:Rh-Hr Blood-Group System / Q000235:genetics
D001324:Autoantigens; D012204:Rh-Hr Blood-Group System