[Research of Subtype A Caused by New A Allele Mutation]

In order to clarify the ABO phenotype and genotype, and explore the molecular biological mechanism, serological detection, genotyping and gene sequencing were performed on an upper gastrointestinal hemorrhage patient with inconsistent forward and reverse ABO blood typing.

ABO forward and reverse blood typing, H antigen identification, capillary centrifugation test and salivary substance detection were performed by classical serological method, moreover, polymerase chain reaction-sequence specific primer (PCR-SSP) was used for ABO genotyping, ABO gene 1-7 exons were sequenced by Sanger analysis in order to identify mutation.

Mixed field agglutination with anti-A, anti-AB and no agglutination with anti-A1 were appeared in the forward typing tests, agglutination with B cells but no agglutination with A1 cells and O cells were appeared in the reverse typing tests. 3+ agglutination strength was showed with anti-H. In capillary centrifugation experiment, erythrocyte after isolation in proximal part and distal end had same strength of agglutination with anti-A. Substances A and H were detected in saliva. The patient was assigned an A3 phenotype according to serological characteristics. Sequencing results of ABO gene 1-7 exons showed c.261delG, c.467C>T, c.865A>G, in which, 865A>G was the first discovered mutation, and this new mutation had been submitted to GenBank with accession number PP187306.

A novel site mutation c.865A>G is reported in this study, and this new mutation can result in a replacement of Met with Val at residue 289 (p.Met289Val) and lead to an A3 phenotype.