Purpose of review: Molecular testing methods were introduced to the blood bank and transfusion medicine community more than a decade ago after cloning of the genes made genetic testing for blood groups, that is genotyping, possible. This review summarizes the progress made in the last decade in applying genotyping to prenatal practice and clinical transfusion medicine.
Recent findings: Assays that target allelic polymorphisms prevalent in all populations are reproducible and highly correlated with red blood cell phenotype. For some blood groups, assays that detect silencing mutations are also required for accurate typing, and for ABO and Rh, multiple regions of the genes must be sampled. Genotyping is a powerful adjunct to serologic testing and is superior for typing transfused patients, for D-zygosity determination, for noninvasive fetal typing, and for antigen-matching in sickle cell patients.
Summary: Implementation of molecular testing for transfusion medicine has been a conservative process and limited primarily to reference laboratory environments. With the development of high-throughput platforms, genotyping is poised to move into the mainstream, revolutionizing the provision of antigen-negative donor units. This will enable electronic selection of units antigen matched to recipients at multiple blood group loci, potentially eliminating alloimmunization and significantly improving transfusion outcomes.