Sensitivity and specificity of the B allele-specific PNA-mediated PCR clamping.
(A) Sensitivity of the B-specific PCR. Genomic DNA of the BO genotype was mixed with that of the OO genotype at ratios of 1:10, 1:50, 1:100, and 1:200, followed by B-specific PCR with the PNA ABOc253CLΔ and ABOc278CLA or a control PCR without these PNA. The numbers indicate copy ratios between the B and O alleles. DNA from the subject was also examined using B-specific PCR or non-clamping PCR. TrackIt™ 1kb PLUS DNA Ladder was used as a molecular size marker. (B) Specificity of the B-specific PCR. Direct sequence analyses showed a difference in the nucleotides at position 297 between the B-specific PCR product and the non-clamping PCR product. The sequences are demonstrated between positions 294 and 300 of the cDNA which were obtained from the B-specific PCR or the non-clamping PCR. The change in the nucleotide to G and A at position 297 indicated by an asterisk is associated with the B and A/O allele, respectively.