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 redcell surface has been reported to be a single C-->T 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.