Point mutations in KEL exon 8 determine a high-incidence (RAZ) and a low-incidence (KEL25, VLAN) antigen of the Kell blood group system.

Background and Objectives: The molecular basis of two Kell blood group antigens, RAZ (provisionally KEL27) and VLAN (KEL25), were determined.
Materials and Methods: The DNA sequences of the open reading frames and the flanking intron regions of the 19 KEL exons from RAZ and VLAN probands were compared with that of common KEL. Genotyping assays were designed to confirm and detect RAZ and VLAN phenotypes.
Results: A homozygous G865A mutation, encoding lysine instead of glutamic acid at amino acid position 249 of Kell protein, defines the RAZ phenotype, while a heterozygous G863A mutation in KEL, encoding an arginine to glutamine substitution at amino acid 248, characterizes the VLAN phenotype.
Conclusion: Point mutations G865A and G863A, in adjacent codons of KEL exon 8, which cause amino acid substitutions, characterize the RAZ and VLAN Kell blood group phenotypes.