Applications of molecular genotyping to immunohaematology.

The genes encoding 20 of the 23 blood group systems have been cloned and sequenced. This has allowed the determination of the molecular basis of many blood group antigens and phenotypes. In this review we outline the basis of the genetic code, summarise molecular events that give rise to polymorphic antigens and to blood group phenotypes, and describe how polymerase chain reaction-based techniques can be applied in the clinical setting.