Prevalence and distribution of serological characteristics of weak ABO subgroups in the Chinese population.

Objectives: This study aimed to determine the true frequency of weak ABO subgroups and to investigate the serological characteristics of various subgroup alleles in the Chinese population.

Methods: A total of 2,945,643 blood samples were collected from January 2009 to December 2017. After initial screening and re-examination using automatic blood group analyzers, all ABO-discrepant samples were confirmed by standard serological analysis and molecular detection by DNA sequencing. The true frequency of weak ABO subgroups was determined by the number of ABO subgroup donors and the missed detection rate. The ABO antigen expressions corresponding to subgroup alleles were analyzed by the agglutination intensity of red blood cells.

Results: The detection rate of ABO subgroups was 0.031 % (927/2,945,643). Considering the missed detection rate (27.81 %), the true frequency of ABO subgroups in the Chinese population was 0.044 %. The three most common genetic variations among blood donors in Shanghai were BA.04, BW.12 and BA.02. BW.03 showed the weakest B antigen expression (6.00 ± 1.97) and B the strongest (9.20 ± 1.10).

Conclusion: Many ABO subgroups were missed. BA.04 was found to be the most common subgroup allele in the Chinese population. Different ABO subgroup alleles exhibit different ABO antigen expression patterns.