Three missense mutations found in the KEL gene lead to K(mod) or K0 red blood cell phenotypes

The KEL gene is highly polymorphic. It presents two major alleles, KEL1(K) and KEL2(k), but a variety of mutations give rise to weakened (K(mod) phenotype) or lack (K0 phenotype) of Kell antigen expression. Recently, the use of advanced DNA-based techniques has greatly increased our understanding of the Kell blood group system.

Three blood samples that had shown discordant results between the serologic and molecular typing for k were investigated by DNA sequencing. Two of these samples were also subjected to studies of adsorption and elution.

After sequencing the whole KEL gene, we found three new missense mutations: c.455A>G (p.Tyr152Cys) at Exon 5, c.2111A>C (p.Pro704His) at Exon 19, and c.1726G>C (p.Gly576Arg) at Exon 16. So far, no known clinical implications are associated with these mutations. Further investigation by adsorption and elution methods has defined that c.455A>G and c.1726G>C resulted in K0 phenotype, while c.2111A>C encoded a K(mod) phenotype.

Molecular investigation is an important complement to routine serologic analyses of Kell antigens. Discrepancies between genotype and phenotype may reveal the presence of K(mod) or K0 phenotypes. Our description of three new KEL alleles suggests a role for a wider diagnostic approach to typing of the Kell system.