Premium
Novel alleles at the JK blood group locus explain the absence of the erythrocyte urea transporter in European families *
Author(s) -
Irshaid Nidal M.,
Eicher Nicole I.,
Hustinx Hein,
Poole Joyce,
Olsson Martin L.
Publication year - 2002
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.2002.03238.x
Subject(s) - biology , genetics , genotyping , allele , null allele , locus (genetics) , microbiology and biotechnology , exon , genotype , gene
Summary. The Kidd (JK) blood group system is of importance in transfusion medicine. The Jk null phenotype is associated with absence of the urea transporter in erythrocytes and moderately reduced ability to concentrate urine. We and others recently reported different molecular alterations in the silenced Jk b ‐ like alleles of Polynesians and Finns, populations with higher Jk null frequencies. Here we report novel molecular bases of this phenotype in Caucasians. Blood samples from a Swiss and an English family were investigated by serological methods, urea haemolysis test and JK genotyping. Genomic DNA and JK mRNA were sequenced. Genotyping showed homozygosity for Jk a ‐like alleles. The Swiss Jk null alleles deviated from wild‐type Jk a sequence by a nonsense mutation in exon 7 causing an immediate stop codon (Tyr194stop). The English Jk null alleles revealed a genomic 1·6 kilobase pair deletion including exons 4 and 5, the former of which includes the translation start codon. Multiple mRNA splicing variants were detected in reticulocytes but exons 3–5 were absent in all transcripts analysed. Screening for these alleles was negative in random donors. Two novel molecular alterations at the JK locus were defined and a multiplex polymerase chain reaction method for detection of the five known silent Jk alleles was developed to complement JK genotyping in clinical transfusion medicine.