The mutation spectrum of the JK-null phenotype in the Chinese population

Background: This study aimed to analyze the mutation spectrum of the JK-null phenotype in the Chinese population. The JK gene encoding the Kidd blood group antigen protein and JK*A/JK*B polymorphism caused by a G-to-A mutation at nt838 are well described. However, the molecular basis of the JK-null phenotype in Chinese populations remains unclear.

Study design and methods: Sixteen unrelated JK-null phenotype donors detected by red blood cell urea lysis resistance assay of 201,194 Chinese blood donors were confirmed in serologic agglutination tests. JK-null alleles were analyzed by MnlI polymerase chain reaction-restriction fragment length polymorphism and sequencing of all JK gene coding regions.

Results: In addition to the well-known Polynesian JK-null allele JK*B(IVS5-1g>a) and two alleles discovered in Taiwan, JK*B(896G>A) and JK*B(222C>A), seven JK-null allele types were detected in this study including four novel JK-null alleles: a nonsense mutation, JK*B(512G>A); two types of missense point mutations, JK*B(536C>G) and JK*B(437T>C); and a splice mutation, JK*A(IVS8+5g>a), resulting in skipping of Exon 8.

Conclusion: This study demonstrates the frequency and heterogeneity of the JK-null phenotype in Chinese populations. Based on our findings, the mechanisms underlying the Chinese Jk(a-b-) phenotype are quite different from other ethnic groups. The two most common types of JK-null alleles were JK*B(IVS5-1g>a) and JK*B(896G>A) in Chinese persons. Four novel JK-null alleles were noted to be associated with the Jk(a-b-) phenotype.