4. Conclusions and wider implications
This study has successfully optimised two extraction methods
capable of extracting DNA from toenail material. The protocol
utilising the QIAGEN DNA Investigator Kit has been shown to
successfully recover sufficient DNA from toenail samples from
decomposed remains (case work) for STR profiling for identification
purposes. Even with toenails mostly displaying an overall
poorer profile quality when compared to the conventional sample
for that case, the profiles for 28 of the toenails would have been
suitable for identification with the remaining two profiles
requiring a minor mixture component to be resolved in order to
produce a full profile. Alternatively, a more rigorous wash step
could be utilised prior to extraction to increase the chance of
removing the contaminant DNA leading to a single source profile.
The advantages of using toenail samples as opposed to bone
include: reduced OH&S risks; faster sample collection and
subsequent processing in the DNA analysis pipeline – leading to
identification in quicker timeframes which is of significant benefit
to the family; convenient storage conditions; and reduction of the
invasiveness of the procedure for the deceased. Such outcomes far
outweigh the lesser profile quality – on average – elucidated by
this study for toenail samples. However, it should also be noted
thatfor some cases,the DNA profile obtained for the toenail sample