A new PCR method: one primer amplification of PCR-CTPP products

Polymerase chain reaction with confronting two-pair primers (PCR-CTPP) is a convenient method for genotyping single nucleotide polymorphisms, saving time, and costs. It uses four primers for PCR; F1 and R1 for one allele, and F2 and R2 for the other allele, by which three different sizes of DNA are amplified; between F1 and R1, between F2 and R2, and between F1 and R2. To date, we have applied PCR-CTPP successfully for genotyping more than 60 polymorphisms. However, it is not rare that PCR does not produce balanced amplification of allele specific bands. Accordingly, the method was modified by attaching a common sequence at the 5' end of two-pair primers and adding another primer with the common sequence in PCR, in total five different primers in a tube for PCR. The modification allowed one primer amplification for the products of initial PCR with confronting two-pair primers, named as one primer amplification of PCR-CTPP products (OPA-CTPP). This article demonstrates an example for an A/G polymorphism of paraoxonase 1 (PON1) Gln192Arg (rs662). PCR-CTPP failed clear genotyping for the polymorphism, while OPA-CTPP successfully produced PCR products corresponding to the allele. The present example indicated that the OPA-CTPP would be useful in the case that PCR-CTPP failed to produce balanced PCR products specific to each allele.