Different Genotypes Causing Indiscernible Patterns of A Expression on A el Red Blood Cells as Visualized by Scanning Immunogold Electron Microscopy

Background and Objectives: The published sequence of the weak A subgroup Ael gene from Swedish individuals showed a G insertion in exon VII, causing a frameshift at ccdon 268 (the A01 gene has 353 codons). We wished to sequence exons VI and VII of two Norwegian Ael individuals and compare the expression of A substance on RBC from different A el individuals. Materials and Methods: Exon VI and VII were amplified by PCR, cloned in M13 and sequenced. A structure expression on Ael RBC was studied by the immunogold technique. Results: In contrast to the Swedish Ael individuals, the two Norwegians had consensus A01 sequences in exon VI and VII. However, the patterns of A expression were indiscernible from the Swedish cases as visualized by immunogold labeling in SEM. In both cases, a few (1–2%) RBC were very strongly labeled, some were weakly labeled and the majority (95%) were unlabeled. Conclusion: Although some Ael individuals have an inserted nucleotide in exon VII of the ABO gene, others have consensus A01 sequence in exon VI and VII. However, we could not find any differences in phenotype by immunogold labeling in SEM.