A sampling of DNA evidence comprises of extraction, quantification, and STR amplification. Nevertheless, there can be a loss of DNA in the event of extraction and quantification. This is not idyllic for forensic evidence which contains low DNA levels. To enable extraction and quantification, researchers suggest the use of direct PCR modification of unknown forensic samples. It helps in the retaining of DNA, which had been lost in the extraction procedures. This can also assist in enhancing the generation of genotyping data from such samples.
The use of direct PCR commenced in the mid-2000s, where commercial direct STR amplification kits were used (Cavanaugh & Bathrick, 2018). Direct PCR applied involved the use of advanced buffer-polymerase technology, which is vital in that it overcame the influences of the common PCTR inhibitors. In 2010, there was the application of the direct PCR to type sample, which entailed the analysis of DNA without DNA extraction. This involved fabric cuttings and swabbing of worn clothing items, subject to direct PCR. Other methodologies used for the evaluation of low-level and low-quality DNA are relatively prone to stochastic effects.
The study’s findings demonstrate that the viability and utility of direct PCR of forensic touch have been commendably demonstrated. The direct PCR has been implemented successfully into workflows for high through reference data banking samples and evidentiary blood samples. Many laboratories have adopted this method, since it ensures that there are faster results, turnaround times, fiscal savings and alleviated bottlenecks. Nevertheless, many laboratories are yet to employ direct PCR, due to the routinely may guidelines which prevent its implementation.
Cavanaugh, S. E., & Bathrick, A. S. (2018). Direct PCR amplification of forensic touch and other challenging DNA samples: a review. Forensic science international: Genetics, 32, 40-49.