Development of a PCR‐based diagnostic assay for the determination of KEL genotype in donor blood samples

The polymorphism which determines expression of Kell and Cellano antigens on the red-cell surface has been reported to be a single CT nucleotide substitution at residue 701 where T codes for the presence of Kell antigen. This was confirmed by the direct automated sequencing of PCR products amplified from individuals of known Kell phenotype. The substitution creates a Bsm I restriction enzyme site and this has formed the basis for the development of a PCR-based diagnostic assay for the determination of Kell phenotype in samples of donor blood. The assay is based on RFLP analysis of coamplified PCR products, one of which spans the K/k polymorphic site, and one control fragment which contains a Bsm I site. Digestion of the PCR products with Bsm I restriction enzyme and subsequent gel analysis of the digest allowed unequivocal determination of the K/k status of all of the samples tested.