Primary template directed amplification (PTA) is a whole genome amplification technique used to amplify low picogram DNA to microgram quantity for various downstream applications. The reactions takes advantage of the high fidelity phi29 polymerase with strand displacement activity and generates amplification product from random primers (6-9mer) annealed to primary template. Exonuclease-resistant terminators are incorporated into the reaction to create smaller double-stranded amplification products that undergo limited subsequent amplification. This transforms the reaction from exponential into a quasilinear process with more of the amplification occurring from the primary template.