Figure 1.

Schematic illustration of primers and PNA used for allele-specific PNA-mediated PCR clamping.

Two common nucleotide primers, ABO+17674S and +17765AS, used for PCR amplification, are indicated by arrows, while the PNA ABO+c253CLΔ, ABO+c278CLA and ABO+c278CLG are represented by squares with the corresponding sequences. The genomic sequence between positions +17674 and +17765 relative to the translation start site of the human ABO gene is shown. The sequence was from genomic DNA from the B allele (GenBank accession number AJ920329.1). The nucleotides in exon 6 are denoted by the upper letters, while those in intron 5 are denoted by the lower letters. c261 shows the location of nucleotide G, which is absent from the O alleles including O01 and O02. c297 indicates the location of nucleotide A or G at position 297 on the cDNA which is associated with the A/O or B allele, respectively.