Evaluation of a blood group genotyping platform (BLOODchip(®) Reference) in Japanese samples

Blood-group genotyping arrays have been widely used in Caucasian and African American populations, but have not been thoroughly tested in Japanese subjects.

To evaluate, using the BLOODchip(®) Reference genotyping system, the concordance of previously typed samples with expected phenotypes and the coverage of the Japanese variants.

Blood samples from 100 Japanese donors were obtained. DNA was extracted with QIAsymphony (Qiagen, Hilden, Germany). Samples were typed by serological methods and processed with the BLOODchip(®) . When a non-concordant result was identified, further sequencing by polymerase chain reaction-single specific primer (PCR-SSP) was performed.

Concordance between systems was 98% (736/751), and 98.8% (742/751) if only non-software-related non-concordances were considered. In the ABO group, 6 'No Call' (NC, inability of the BLOODchip(®) to assign a result) were ascribed to a variant of blood subtype A1 (A102; 467C>T), a common subtype in Asian populations, whereas three NC presented additional polymorphisms not contained in the BLOODchip(®) (A102/A205, A102/O06 and A204/O02). In the RhD group, one discrepancy was correctly genotyped as RHD*1227A (Del phenotype) by the BLOODchip(®) (phenotyped as partial D, RHD*DIVb). Another was phenotyped as D+ by the BLOODchip(®) (phenotyped weak D by serology) and confirmed as RHD*D-CE(2)-D heterozygous by sequencing. The 3 RhD NC can be solved by further software update. For RhCE, one discrepancy was correctly genotyped for both systems; however, only the BLOODchip(®) was able to detect RHCE*CX allele.

By programming the A102 ABO variant into the system software with the new allele combinations, the BLOODchip(®) Reference is a suitable genotyping tool to be applied to Asian samples.