To prevent carryover contamination, dUTP (NEB #N0459) and Antartic Themolabile UDG (NEB #M0372) can be added to the reaction. For best results, we recommend adding dUTP at a final concentration of 200 μM. dTTP can be fully replaced by dUTP and for many targets, no reduction in yield is observed. For UDG activation, a 10 minute, 25°C incubation step should be added before the initial denaturation step. Typical cycling parameters can be used thereafter.