Abstract
Physical contact can result in the transfer of DNA from one individual to another.
In cases of sexual offence this can often be by means of an aggressive or sexual act.
Biological material can accumulate under the fingernail hyponychium of both the victim
and/or the suspect and has the potential to provide evidence and intelligence information
to the police.
The incidence of mixed DNA profiles obtained from fingernail samples of couples who
co-habit was explored using AmpFlSTR® SGM Plus® (SGM Plus) (Applied Biosystems®). It was predicted that the higher incidence of contact from co-habitation and therefore
the greater opportunity for DNA transfer would result in an increased level of foreign
DNA from the partner under the donor's fingernails. Fingernail swabs were taken from
all fingers of the left and right hands of 12 couples on three separate occasions.
DNA profiles were compared to both the donor and partner's reference DNA profiles.
The number of reportable mixed DNA profiles obtained (17%) was higher than in previous
reports. In this study, the majority of non-donor alleles matched the partner's reference
DNA profile, indicating that co-habitation affected non-donor DNA obtained from fingernail
swabs. The results demonstrated that as the couples spent increasing amounts of time
together, the incidence of mixed DNA profiles increased. The large variation in the
incidence of foreign alleles observed within and between couples suggested that a
combination of lifestyle factors were having a significant effect on whether mixed
DNA profiles were observed.
Further DNA profiling using the AmpFlSTR® Y-filer® (Yfiler) PCR amplification (Applied Biosystems) was carried out to determine whether
female fingernail samples that had previously given single donor profiles contained
low levels of male DNA that may be detected by targeting the Y-chromosome. It was
found that 63% of the samples analysed using Yfiler produced full or partial Y-STR
profiles. The Y-STR profiles were compared to partners’ profiles and searched through
two haplotype databases to determine the evidential value of such samples.
Keywords
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Article info
Publication history
Published online: November 05, 2008
Accepted:
September 18,
2008
Received in revised form:
June 27,
2008
Received:
April 23,
2008
Footnotes
☆All work carried out at The Forensic Science Service®.
Identification
Copyright
© 2008 Published by Elsevier Inc.
