Get access

Identification of novel silent KEL alleles causing KEL:−5 (Ko) phenotype or discordance between KEL:1,−2 phenotype/KEL*01/02 genotype

Authors

  • Stéphanie Martin-Blanc,

    1. Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, Paris
    2. CHU Réunion, Site Sud, Saint Pierre, France
    Search for more papers by this author
  • Philippe Simon,

    1. Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, Paris
    2. CHU Réunion, Site Sud, Saint Pierre, France
    Search for more papers by this author
  • Dominique Gien,

    1. Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, Paris
    2. CHU Réunion, Site Sud, Saint Pierre, France
    Search for more papers by this author
  • Sandrine Kappler-Gratias,

    1. Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, Paris
    2. CHU Réunion, Site Sud, Saint Pierre, France
    Search for more papers by this author
  • Pierre-Yves Le Pennec,

    1. Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, Paris
    2. CHU Réunion, Site Sud, Saint Pierre, France
    Search for more papers by this author
  • Bach-Nga Pham

    Corresponding author
    1. Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, Paris
    2. CHU Réunion, Site Sud, Saint Pierre, France
    • Address reprint requests to: Bach-Nga Pham, Institut National de la Transfusion Sanguine, CNRGS–INSERM U665, 20 rue Bouvier; BP 79, 75522 Paris Cedex 11, France; e-mail: bnpham@chu-reims.fr.

    Search for more papers by this author

Abstract

Background

The Kell system, encoded by the KEL gene, is one of the most clinically important blood group systems. Molecular defects may lead to the absence of Kell antigen expression. The very rare KEL:5 results from silent KEL genes, also called KELnull alleles. In a few cases, the rare KEL:1,−2 phenotype may be associated with silent KEL*02 alleles.

Study Design and Methods

The aim of this study was to perform DNA investigations to identify silent KEL alleles among 10 KEL:–5 patients and 121 individuals presenting the rare KEL:1,−2 phenotype. Serologic investigations were performed on patients' red blood cells and serum. The KEL gene analysis was done by using a BeadChip assay (HEA Version, 1.2, Immucor), real-time polymerase chain reaction, and/or sequencing of all 19 exons of the KEL gene.

Results

In KEL:–5 patients, two novel KELnull alleles were described: 821G>A being the second described KELnull allele on a KEL*01 backbone and 184Tdel. In the 121 KEL:1,−2 individuals, nine (7.4%) were found to display a discordant KEL:1,−2 phenotype and KEL*01/KEL*02 genotype. Three novel silent KEL*02 alleles were described: 1084C>A, 1708G>A, and IVS11+5g>a.

Conclusion

The number of silent KEL alleles and the notion that KEL null alleles are on a KEL*02 background may evolve in the coming years. Systematic DNA analysis showed that the number of discordant phenotype/genotype results, related to silent KEL*02 alleles was higher than expected in France. These data emphasize that clinical practice based on DNA analysis for blood group antigens requires caution and should improve the performance of the blood group phenotype prediction.

Ancillary