Transfusion. 2007 Apr;47(4):703-14.
Genetic diversity of KELnull and KELel: a nationwide Austrian survey.
Körmöczi GF, Wagner T, Jungbauer C, Vadon M, Ahrens N, Moll W, Mühlbacher A, Ozgül-Gülce S, Kleinrath T, Kilga-Nogler S, Schönitzer D, Gassner C.
Besides ABO and RH, the KEL blood group system, including the two antithetical antigens KEL1 and KEL2, is the most important owing to the frequent appearance of anti-KEL alloantibodies and their considerable clinical significance. So far, only limited information was available on KEL variant alleles determining the rare silent KELnull and KELel phenotypes with absent or diminished KEL antigen expression detected only by adsorption-elution techniques, respectively.
Study design and methods
For a systematic investigation of the KELnull and KELel phenotypes, 401 KEL:1,-2 samples (representing 2.6% of all Austrian KEL:1,-2 samples) and 811 KEL:1,2 samples were genotyped for the KEL1/KEL2-specific single-nucleotide polymorphism. All heterozygous KEL1/KEL2 and 4 additional KELnull samples were subjected to detailed immunohematologic examination and allele-specific sequencing.
In 14 KEL:1,-2 samples, discrepant KEL1/KEL2 heterozygosity was observed, indicating the presence of silent or barely expressed KEL2 alleles, whereas all KEL:1,2 individuals were homozygous for KEL2. In the course of further molecular analysis, 8 novel KEL2null and 2 KEL2el alleles were discovered, representing 67 and 33 percent of previously known KEL2null- and KEL2el-encoding alleles, respectively. In addition, two different known KEL2null and KEL2el alleles each were confirmed. The immunohematologic properties of KEL variant red blood cells were defined by extended KEL phenotyping and flow cytometric KEL1, KEL2, KEL4, and KEL7 antigen as well as total Kell protein quantification.
For the first time, exact KELnull and KELel population frequencies could be established in this population.