Silent KEL alleles identified from Japanese individuals with the K phenotype.

BACKGROUND AND OBJECTIVE

The rare K phenotype lacks all 36 antigens in the Kell blood system. The molecular basis of the K phenotype has been investigated, and more than 40 silent KEL alleles are reported by many investigators. The majority of silent alleles are the KEL*02 background. Here, we report molecular genetic analysis of the KEL gene in Japanese individuals with the K phenotype.

MATERIALS AND METHODS

The K phenotype was screened from Japanese blood donors for several years using monoclonal anti-Ku or anti-K14 by an automated blood grouping system PK7300. Kell-related antigens were typed by standard tube tests. Genomic DNA was extracted from the blood samples, and KEL gene was analysed by polymerase chain reaction (PCR) and Sanger sequencing.

RESULTS

We collected 35 K blood samples with K-k-, Kp(a-b-), Js(a-b-) and K14-. PCR and sequence analysis revealed that 11 individuals were homozygous for a mutant KEL allele with a c.299G>C (p.Cys100Ser) mutation (rs. 200268316). Three individuals were homozygous for the KEL02N.24 allele that is c.715G>T (p.Glu239), and one individual was homozygous for the KEL02N.40 allele that is c.1474C>T (p.Arg492). Five individuals were homozygous for novel KEL alleles with single-nucleotide mutations, four individuals had a c.2175delC (p.Pro725 fs43), and one individual had a c.328delA (p.Arg110 fs79). The remaining 15 individuals were compound heterozygous, and eight new alleles were identified from them.

CONCLUSIONS

We identified three known and ten new silent KEL alleles from Japanese individuals with the K phenotype. The KEL allele with the c.299G>C (p.Cys100Ser) mutation was the most frequent.