Identification of an A_weakB phenotype caused by significant ABO gene deletion in a Chinese woman

The A_weakB is a rare phenotype in the ABO blood group system. Here, we first report a novel ABO mutation discovered in a Chinese woman with an A_weakB. Third-generation sequencing was employed to investigate the molecular mechanisms underlying A_weakB. By correctly identifying the phenotype, it was useful for increasing the safety of blood transfusion.

ABO blood group was identified by the standard ABO serological test and polymerase chain reaction with sequence-specific primers (PCR-SSP). To analyse the ABO gene sequence, single-molecule real-time (SMRT) sequencing was performed to obtain full-length sequencing of the ABO gene.

The Chinese individual was serologically identified as A_weakB subtype, and SMRT sequencing analysis revealed that there were large fragment deletion mutations in the promoter (c.1-1326_1-1321del, c.1-1010_1-975del, c.1-952_1-1del) and Exon 1 region (c.1_28del).

We report for the first time that large fragment deletions represent a novel molecular basis for the A_weakB. These deletions may potentially influence the expression of the A antigen.