title: Genetic and mechanistic evaluation for the weak A phenotype in Ael blood type with IVS6 + 5G>A ABO gene mutation.
abstract: OBJECTIVE
  Ael is a rare blood type that is characterized by weak agglutination of RBCs when reacts with anti-A antibody in adsorption-elution test. Although IVS6 + 5G→A mutation is known to associate with the Ael blood type, genetic and mechanistic evaluation for the weak agglutination of Ael with IVS6 + 5G→A mutation has not yet been completely addressed.
  
  
  METHODS
  In this study, five cases of confirmed Ael individuals were analysed. The cDNAs for the A(el) alleles were obtained by cloning method for sequence analyses. The erythroleukemia K562 cells were used as the cell study model and were transfected with the A(el) expression construct. Flow cytometry analysis was then performed to determine the levels of surface antigen expression.
  
  
  RESULTS
  The results indicated that IVS6 + 5G→A attributes to all cases of Ael . RT-PCR analyses revealed the presence of at least 10 types of aberrant A(el) splicing transcripts. Most of the transcripts caused early termination and produced non-functional protein during translation. Nevertheless, the transcript without exons 5-6 was predicted to generate functional Ael glycosyltransferase lacking 57 amino acids at the N-terminal segment. When the exons 5-6 deletion transcript was stably expressed in the K562 cells, weak agglutination of the cells can be induced by adding anti-A antibody followed by adsorption-elution test.
  
  
  CONCLUSIONS
  This study demonstrates that aberrant splicing of A transcripts contributes to weak A expression and the weak agglutination of Ael -RBCs, adding to the complexity for the regulatory mechanisms of ABO gene expression.
authors.affiliation: Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan County, Taiwan; Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan County, Taiwan.
authors.forename: D-P
authors.initials: DP
authors.lastname: Chen
authors.forename: C-F
authors.initials: CF
authors.lastname: Sun
authors.forename: H-C
authors.initials: HC
authors.lastname: Ning
authors.forename: C-T
authors.initials: CT
authors.lastname: Peng
authors.forename: W-T
authors.initials: WT
authors.lastname: Wang
authors.forename: C-P
authors.initials: CP
authors.lastname: Tseng
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D000483:Alleles; D001788:Blood Grouping and Crossmatching; D045744:Cell Line, Tumor; D005091:Exons; D006801:Humans; D009154:Mutation; D010641:Phenotype
chemical_list: D000017:ABO Blood-Group System
keywords: Ael blood type; adsorption-elution test; cell study model; point mutation; splicing error; weak agglutination