Optimization of annealing temperature and amount of high-fidelity DNA polymerase in the modified PR-PCR. (a) Discrimination efficiency of the modified PR-PCR for known mutations using a mixture of 1 U of Taq DNA polymerase and various amount (0.05, 0.1 and 0.3 U) of KOD FX DNA polymerase in the reaction. The PCR amplifications were performed in a total volume of 20 μL under cycling conditions consisting of pre-denaturation at 94°C for 2 min, followed by 30 cycles of denaturation at 94°C for 20 s, annealing at 56°C for 20 s and extension at 72°C for 25 s. (b) Optimization of annealing temperature for the modified PR-PCR using a mixture of 1 U of Taq DNA polymerase and 0.1 U of KOD FX DNA polymerase. As the optimal discrimination efficiency was obtained when the annealing temperature was within a scope of 61.8°C–62.6°C, the results from 50°C to 61.2°C were not shown. The temperature 62.2°C was selected for subsequent experiments. (c) Optimization of amount of high-fidelity DNA polymerase for the modified PR-PCR with an input of 1 U of Taq DNA polymerase at an annealing temperature of 62.2°C.