Forensic DNA Testing

There have been two main types of forensic DNA testing. They are often called, rflp and pcr-based tests, although these terms are not very descriptive. Overall, the rflp test requires large amounts of dna and the dna must be degraded. Evidence of the crime scene that is old or present in small amounts is often unsuitable for rflp testing. Hot, humid conditions may accelerate dna degradation rendering it unsuitable for rflp in a relatively short period of time. Pcr-based testing often requires less dna than rflp testing and dna may be partially degraded, rather than in the case of rflp. However, pcr still has the sample size and degradation of the limitations that can sometimes be underestimated. Pcr tests are also extremely sensitive to contamination of dna at the crime scene and lab tests. During pcr, contaminants may be extended up to one billion times their original concentration.

Contamination may affect the results of pcr, particularly in the absence of management techniques and appropriate controls pollution. The pcr is less direct and more prone to errors rflp. However, the pcr has tended to replace rflp in forensic evidence especially because the pcr-based tests are faster and more sensitive.