title: A KEL gene encoding serine at position 193 of the Kell glycoprotein results in expression of KEL1 antigen.
abstract: BACKGROUND
  The KEL2/KEL1 (k/K) blood group polymorphism represents 578C>T in the KEL gene and Thr193Met in the Kell glycoprotein. Anti-KEL1 can cause severe hemolytic disease of the fetus and newborn. Molecular genotyping for KEL*1 is routinely used for assessing whether a fetus is at risk. Red blood cells (RBCs) from a KEL:1 blood donor (D1) were found to have abnormal KEL1 expression during evaluation of anti-KEL1 reagents.
  
  
  METHODS
  Kell genotyping methods, including KEL exon 6 direct sequencing, were applied. KEL cDNA from D1 was sequenced. Flow cytometry was used to assess KEL1 and KEL2 RBC expression.
  
  
  RESULTS
  RBCs from the donor, her mother, and an unrelated donor gave weak or negative reactions with some anti-KEL1 reagents. Other Kell-system antigens appeared normal. The three individuals were homozygous for KEL C578 (KEL*2) but heterozygous for a 577A>T transversion, encoding Ser193. They appeared to be KEL*2 homozygotes by routine genotyping methods. Flow cytometry revealed weak KEL1 expression and normal KEL2, similar to that of KEL*2 homozygotes.
  
  
  CONCLUSIONS
  Ser193 in the Kell glycoprotein appears to result in expression of abnormal KEL1, in addition to KEL2. The mutation is not detected by routine Kell genotyping methods and, because of unpredicted KEL1 expression, could lead to a misdiagnosis.
authors.affiliation: Bristol Institute for Transfusion Sciences and International Blood Group Reference Laboratory, Bristol, UK.
authors.forename: Joyce
authors.initials: J
authors.lastname: Poole
authors.forename: Nicole
authors.initials: N
authors.lastname: Warke
authors.forename: Hein
authors.initials: H
authors.lastname: Hustinx
authors.forename: Behrouz Mansouri
authors.initials: BM
authors.lastname: Taleghani
authors.forename: Peter
authors.initials: P
authors.lastname: Martin
authors.forename: Kirstin
authors.initials: K
authors.lastname: Finning
authors.forename: Vanja Karamatic
authors.initials: VK
authors.lastname: Crew
authors.forename: Carole
authors.initials: C
authors.lastname: Green
authors.forename: Imelda
authors.initials: I
authors.lastname: Bromilow
authors.forename: Geoff
authors.initials: G
authors.lastname: Daniels
mesh_terms: D000328:Adult; D001483:Base Sequence / Q000235:genetics*; D001782:Blood Donors; D004252:DNA Mutational Analysis / Q000379:methods; D018076:DNA, Complementary / Q000235:genetics; D004899:Erythroblastosis, Fetal / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D005315:Fetal Diseases / Q000235:genetics; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007231:Infant, Newborn; D007626:Kell Blood-Group System / Q000235:genetics*; D008297:Male; D020125:Mutation, Missense; D020641:Polymorphism, Single Nucleotide
chemical_list: D018076:DNA, Complementary; D006023:Glycoproteins; D007626:Kell Blood-Group System