title: [A KEL*02mod allele responsible for an apparent maternity exclusion].
abstract: The patient's rare KEL:1,-2 phenotype was highlighted in course of a routine preoperative erythrocyte typing. Unexpectedly, her two daughters presented a KEL:-1,2 phenotype what appeared first as an apparent maternity exclusion. Flow cytometry, genotyping and adsorption-elution analyses were then performed for those three patients. KEL genotyping showed that the patient's genotype was KEL*01/KEL*02 whereas that of her daughters was KEL*02/KEL*02. By using polyclonal anti-KEL2 reagent, weak amount of KEL2 was identified on the patient's erythrocytes, a result which was confirmed by both flow cytometry and adsorption-elution assays, suggesting that patient's phenotype was in fact KEL:1,2w. These results are in favour of a weak expressed KEL*02 allele (KEL*2mod) transmission coding for a KEL2 antigen detected in some technical conditions only. Those results allowed to explain the apparent maternity exclusion based on initial KEL phenotype. This study also seems to confirm the presence of a compensatory mechanism of the KELmod allele deficient expression in heterozygote patients. A KEL phenotype retrospective study of 80,000 subjects showed a local KEL:1,-2 frequency four times lower than that described in literature. Moreover, a significant number of those individuals would in reality be KEL:1,2w, what still would decrease the real frequency of the KEL:1,2 subjects.
authors.affiliation: Laboratoire d'immunohématologie, centre hospitalier universitaire de Liège, Liège, Belgique. Electronic address: melanie.monfort@chu.ulg.ac.be.
authors.forename: M
authors.initials: M
authors.lastname: Monfort
authors.forename: T
authors.initials: T
authors.lastname: Peyrard
authors.forename: L
authors.initials: L
authors.lastname: Arnaud
authors.forename: V
authors.initials: V
authors.lastname: Helias
authors.forename: G
authors.initials: G
authors.lastname: Maggipinto
authors.forename: C
authors.initials: C
authors.lastname: Gérard
mesh_terms: D000327:Adsorption; D000483:Alleles; D000937:Antigen-Antibody Reactions; D016477:Artifacts; D001788:Blood Grouping and Crossmatching / Q000379:methods*; D005260:Female; D005434:Flow Cytometry; D005554:Forensic Medicine / Q000379:methods; D005786:Gene Expression Regulation; D005838:Genotype; D060005:Genotyping Techniques; D006386:Hemagglutination Tests; D006801:Humans; D007518:Isoantibodies / Q000276:immunology; D007626:Kell Blood-Group System / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D008666:Metalloendopeptidases / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D009035:Mothers; D010641:Phenotype; D011300:Preoperative Care
chemical_list: D007518:Isoantibodies; D007626:Kell Blood-Group System; D008562:Membrane Glycoproteins; C585978:KEL protein, human; D008666:Metalloendopeptidases
keywords: Allelic expression; Blood group; Exclusion de maternité; Expression allélique; Groupe sanguin; KEL; KEL(mod); Maternity exclusion