Molecular genetic analysis of the Kidd blood group system in a Taiwanese family with Jknull phenotype
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KeyWord:blood group, Kidd, JK, Jknull
Fang-Yeh Chu Department of Clinical Pathology, Far Eastern Memorial Hospital, New Taipei, Taiwan,China; School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei, Taiwan,China; Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan, Taiwan,China; Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsinchu, Taiwan,China;
Lung-Chih Yu Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan,China;
Chih-Chun Chang Department of Clinical Pathology, Far Eastern Memorial Hospital, New Taipei, Taiwan,China;
Marie Lin Transfusion Medicine Laboratory, Mackay Memorial Hospital, Taipei, Taiwan,China.
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      Two common polymorphisms of 588G/A and 838G/A have been demonstrated in the JK gene, and the latter defines the Jka/Jkb phenotypes. The Jknull phenotype has been characterized as the absence of Jka and Jkb antigen expression on red cells. We performed a molecular analysis of a family with the Jknull phenotype and subsequently demonstrated the presence of different JK cDNA haplotypes. In the study, three members of a Jknull family and 48 randomly-selected individuals were enrolled. The coding exons of the JK gene of the Jknull family members were amplified by polymerase chain reaction (PCR), and the sequences were analyzed. The genomic region encompassing exons 7~9 of the JK gene was PCR-amplified, cloned, and sequence-determined to elucidate the JK haplotype. We demonstrated that 3 missense mutations, 222C>A, 499A>G and 896G>A were in the JK genes of the Jknull family members, in addition to the known IVS5–1g>a splice site mutation. Analysis of 48 randomly-selected individuals showed that 499A>G was a common polymorphism, besides 2 Jknull alleles with respective mutation of 222C>A and 896G>A being demonstrated in the Jknull family. After compiling the nucleotide information of the polymorphic 499, 588, and 838 positions from the randomly-selected individuals, 5 JK cDNA haplotypes, constituted by the 3 polymorphic sites, were demonstrated. Among these, the JKa1 (499A, 588G and 838G; 46.9%),JKb1 (499A, 588G and 838A; 23.9%), and JKb2(499G, 588G and 838A; 21.9%) were found as the 3 major haplotypes in the Taiwanese population. In conclusion, the Jknull phenotypes with respective mutations of 222C>A, 896G>A and IVS5–1g>a, were identified in a Taiwanese family. The existence of 5 JK cDNA haplotypes with the 499A/G polymorphism was also demonstrated in the Taiwanese population.