PCR in Forensic Science: A Critical Review

Abstract

The polymerase chain reaction (PCR) has played a fundamental role in our understanding of the world, and has applications across a broad range of disciplines. The introduction of PCR into forensic science marked the beginning of a new era of DNA profiling. This era has pushed PCR to its limits and allowed genetic data to be generated from trace DNA. Trace samples contain very small amounts of degraded DNA associated with inhibitory compounds and ions. Despite significant development in the PCR process since it was first introduced, the challenges of profiling inhibited and degraded samples remain. This review examines the evolution of the PCR from its inception in the 1980s, through to its current application in forensic science. The driving factors behind PCR evolution for DNA profiling are discussed along with a critical comparison of cycling conditions used in commercial PCR kits. Newer PCR methods that are currently used in forensic practice and beyond are examined, and possible future directions of PCR for DNA profiling are evaluated.

Keywords: DNA amplification; STR amplification; annealing; denaturation; polymerase chain reaction.

Figure 1

A timeline of PCR evolution within forensic science from 1985 to the present day (2023). 1985–1990 [4,5,14,49], 1990–1995 [19,50,51], 1995–2000 [52,53,54,55,56], 2000–2005 [57,58,59], 2005–2010 [60,61,62], 2010–2015 [63,64,65,66], 2015–2020 [67], and 2020+ [68,69].

Figure 2

A comparison of the steps required to go from the initial crime scene sample to the final product via three different PCR methodologies: traditional PCR (A), quantitative PCR (qPCR) (B), and Rapid DNA (C).