The A_bantu phenotype in the ABO blood group system is due to a splice‐site mutation in a hybrid between a new O¹‐like allelic lineage and the A² allele

Abstract

The A(bantu) phenotype is caused by an O(1bantu)-A(2) hybrid at the ABO locus.

An exonic missense mutation c.28G>A is associated with weak B blood group by affecting RNA splicing of the ABO gene

“…However, despite all the effort, we failed to find B mRNA transcripts with different size; no detectable transcripts associated with the predicted cryptic splice site c.24G were observed. This result is similar to a previous amplification of the transcripts encoded by the A bantu allele . The absence of detectable aberrant B mRNA transcripts suggests either that they became too big to be amplified by PCR (intron retention) or more likely that transcripts other than normally processed mRNA of the ABO gene were just degraded rapidly in vivo.…”

Many genetically defined ABO subgroups exhibit characteristic flow cytometric patterns

“…In 65 of the 94 test samples, we identified 15 and seven different known subgroup alleles represented among the Aweak (Aw) and Bweak (Bw) samples, respectively (Table 1). 7,13,14,[27][28][29][30][31][32][33][34][35][36][37][38][39] To our knowledge no additional factors associated with down regulation of ABO expression, for example, pregnancy 13 or hematologic disease, 10,11 were present among these samples. Some samples did not contain ABO gene mutations known to cause weak A or B expression but were referred to our laboratory due to ABO forward typing discrepancies and suspicion of ABO subgroup status (n = 29; Table 2).…”

ABO, H, and Lewis Systems

“…Over 20 alleles containing 1016delC with additional missense mutations were responsible for a variety of phenotypes, ranging from very weak to nearly A 2 , with the majority displaying A x -like characteristics [216] . A weak A phenotype known as A bantu , found in about 4% of black South Africans [217] , results from a hybrid of the common A 2 allele with 1016delC and an O 1 -like allele ( O 1bantu ), with a cross -over region near exon 5 ( Abantu01 ) [218] . Another similar hybrid allele, with exons 1 -5 derived from a variant O 1v allele and exons 6 and 7 from A 2 ( A201 ), also found in people of African origin, gave rise to an A antigen weaker than that of A 2 phenotype [219] .…”