Molecular basis of Kell blood group phenotypes

The molecular basis of different Kell blood group phenotypes is reviewed. Sequence analysis of the Kel1 gene (KEL) established that single base substitutions, resulting in amino acid changes, are responsible for the different phenotypes. Most of the amino acid substitutions, with the exception of the one responsible for expression of KEL6 (Js(a)), occur at the amino-terminal half of the protein, a domain that has least amino acid homology with a family of zinc endopeptidases, which include neutral endopeptidase 24.11 and endothelin-converting enzyme-1. Some of the genes were expressed in transfected cells and typed with alloantibodies to confirm that the identified mutations are responsible for antigen expression. Clinical applications of Kell blood group genotyping which include prenatal diagnosis to monitor hemolytic disease of the newborn are discussed.