A novel missense mutation nt737T>G of JK gene with Jk(a-b-) phenotype in Chinese blood donors.

ABSTRACT

OBJECTIVES: The aim of this study was to investigate the molecular mechanism of the JK-null phenotype in the Chinese population. BACKGROUND: The Jk(a-b-) phenotype is vanishingly rare and the molecular basis differs between ethnic groups. The information regarding the molecular basis of JK-null alleles in the Chinese population is limited. MATERIALS AND METHODS: Three unrelated Jk(a-b-) phenotype donors were selected from 52 260 randomly blood samples through the urea lysis test and serological analysis. The JK gene-coding regions were amplified by the polymerase chain reaction and the products were sequenced directly. RESULTS: Sequencing results revealed that one sample of JK(*) B alleles carried the well-known Polynesian Jk(a-b-) mutation IVS5-1g>a. Another null allele, also on the JK(*) B background, presented with two heterozygous missense mutation, including nt222C>A(Asn74Lys) in exon 5 and nt896G>A(Gly299Glu) in exon 9. The third null allele carried two heterozygous missense mutations, nt222C>A and a novel allele nt737T>G(Leu246Arg) in exon 8. The family investigation revealed that the proband was JK(*) A(737T>G)/JK(*) B(222C>A). CONCLUSION: The Jk(a-b-) phenotype in the Chinese population shows several different molecular mechanisms. A novel missense mutation nt737T>G of JK gene was found as associated with Jk(a-b-) phenotype.