Overview - FDF Project

Product Overview

Trace DNA – Why FDF Kit?

Background

Trace DNA samples may be defined as any sample which falls below recommended thresholds at any stage of the analysis, from sample detection through to profile interpretation.

Trace DNA analysis has become an integral part of a forensic laboratory's workload and a key tool for investigators.
From long time ago it was reported that DNA profiles could be generated from touched objects. This opened up possibilities and led to the collection of DNA from a wider range of exhibits (including: tools, clothing knives, vehicles, firearms, food, bedding, condoms, lip cosmetics, wallets, jewellery, glass, skin, paper, cables, windows, doors and stones.

Trace DNA analysis necessitates an understanding of factors relating to its collection, extraction, amplification and interpretation, as well as issues relating to contamination and transfer (Roland AH van Oorschot et al).

In some cases, touch DNA forensic samples should be considered as trace DNA ones, according to the potential low template content.

Small amounts of fragmented DNA is present on the surface of the skin and they theorized that these fragments of DNA may be constantly sloughed off the keratinized cornified layer of skin and that sweat may also contain fragmented DNA (Kita, et al).

The presence of sweat helps to contribute to the DNA profile obtained from touch DNA samples. Cell free nucleic acids, or CNAs, (basically free-floating DNA fragments not encapsulated in the cell nucleus) contribute greatly to the total amount of DNA present in a sample with CNAs being detected in the sweat of 80% of healthy individuals tested (Quinones and Daniel).

Regarding DNA extraction, most current methods do not utilize the portion of the sample where CNAs are found - the aqueous portion of the extract – and after centrifugation to collect the cellular material, the supernatant (containing the CNAs) is generally discarded. Changing the extraction methodology to utilize the DNA from the cell-free nucleic acids has the potential to significantly increase the amount of DNA available for profiling (Suzanna R. Ryan).