THE PREVALENCE OF JK*A with c.130A SINGLE NUCLEOTIDE POLYMORPHISM IN THE JAPANESE BLOOD DONORS AND EXPRESSION ANALYSIS OF Jk^a AND Jk3 ANTIGENS ON THEIR RED BLOOD CELLS

Abstract

Anti-Jk^a and anti-Jk^b against the Kidd antigen cause delayed hemolytic transfusion reactions. Detection of the antibodies by crossmatching is difficult and represents a clinical problem. A JK*A allele (JK*01W.01) with c.130G>A in exon 4 of the JK gene encoding an amino acid substitution (p.Glu44Lys) was reported in 2011. This single nucleotide polymorphism (SNP) reduces the expression level of Jk^a and Jk3 antigens. In this study, we examined the prevalence of the c.130A polymorphism and its effect on the expression of Jk^a and Jk3 in Japanese blood donors. The prevalence of c.130A was 38.5% in 2,017 Japanese donors, accounting for 82.6% of JK*01W.01 in JK*A. On the other hand, the prevalence of c.130A in JK*B was only 0.1%. The red blood cells (RBCs) of the individuals with c.130A showed low expression of Jk^a and Jk3 antigens by flow cytometry. As the prevalence of the Jk (a+b+) phenotype is approximately 50% in the Japanese population, more than 80% of Jk (a+b+) donors are expected to have weak expression of the Jk^a antigen on their RBCs. Therefore, it is important to note that weak expression of Jk^a antigen causes false negative crossmatching. If the patient has anti-Jk^a, blood for crossmatching must be confirmed Jk (a-) using an anti-Jk^a reagent with high potency.