Genotype Analysis of the JR Blood Group in an East Asian Population Using Tetra-Primer ARMS-PCR.

OBJECTIVE

The JR blood group system, officially designated ISBT JR 032, consists of a single antigen called Jr. This is a high frequency antigen in most populations. The Jr(a-) phenotype is more prevalent in Japanese and Asian populations. Individuals with the Jr(a-) blood type can be recognized incidentally by the production of anti-Jr(a) antibodies and verified by the existence of two null alleles.

METHODS

We used direct sequencing to analyze the genotype frequency of the null allele () and compared it with East Asian genomic databases. We developed tetra-primer amplification refractory mutation system-polymerase chain reaction (ARMS-PCR), which is a simple, precise method for determining an individual's genotype and suitable for clinical use, and analyzed a cohort of 300 healthy Koreans.

RESULTS

Using direct sequencing, we found that 14 individuals in the cohort carried a heterozygous null allele. We optimized the ARMS-PCR technique to detect and identify this null allele precisely. We identified the presence of this null allele in a heterozygous state using ARMS-PCR.

CONCLUSION

The minor allele frequency of the null allele in the Korean cohort was 2.3%. The estimated genotype frequencies of homozygotes and heterozygotes for this null allele are 0.05% and 4.56%, respectively. The newly developed ARMS-PCR assay would be useful for determining the Jr(a-) antigen status in patients who produce anti-Jr(a) antibodies as well as for selecting Jr(a-) blood donors.