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

Background and Objectives: The published sequence of the weak A subgroup A el gene from Swedish individuals showed a G insertion in exon VII, causing a frameshift at codon 268 (the A 1 gene has 353 codons). We wished to sequence exons VI and VII of two Norwegian A el 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 A el RBC was studied by the immunogold technique. Results: In contrast to the Swedish A el individuals, the two Norwegians had consensus A 1 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 A el individuals have an inserted nucleotide in exon VII of the ABO gene, others have consensus A 1 sequence in exon VI and VII. However, we could not find any differences in phenotype by immunogold labeling in SEM.