A comparison between direct PCR and extraction to generate DNA profiles from samples retrieved from various substrates.

Direct PCR generates DNA profiles from samples without using the extraction process. During sample extraction, DNA may be lost due to the methods used, which can affect the quality of the DNA profile obtained. This is not the case with direct PCR, where the sample is transferred directly into the PCR tube. Here, we report on the ability of direct PCR to generate DNA profiles from low amounts of control DNA retrieved from various surfaces using PowerPlex 16 HS. A comparison is made with samples undergoing a preliminary extraction stage using QiaAmp DNA Micro kits. Samples subjected to direct PCR generated DNA profiles with higher peak heights and lower allele dropout on all the different substrates tested when compared to the samples subjected to extraction. The amount of DNA retrieved from each substrate also varied even though the same amount of starting material was deposited, proving that the type of substrate can affect the retrieval of DNA.