Examination of Firearms Review: 2007 to 2010 - Interpol

3.4.2 Vaginal fluid
The genes that can be used to identify vaginal fluid are human beta-defensin 1
(HBD-1) and mucin 4 (MUC4). A positive result is also observed in menstrual blood,
but not in circulatory blood, semen, and saliva. Menstrual blood can be differentiated
from circulatory blood and menstrual free vaginal swabs by using the gene matrix
metalloproteinase 11 (MMP11) 11 . For the differentiation of vaginal fluid from blood,
semen, and saliva miR124a and miR372 can be used 16 , although the miR372
concentration is only slightly higher in vaginal fluid compared to other body fluids.
3.4.3 Urine
Until now no genes have been described that are truly specific to urine. Nevertheless
Nakazono et al 19 described a method to show the presence of human urine. They
identified human urine by detecting five 17-ketosteroid conjugates with electrospray
ionization liquid chromatography mass spectrometry (ESI-LC-MS). At the same time
they used diafiltration to purify DNA from the sample and full DNA profiles could be
successfully obtained using capillary electrophoresis. Remarkable however, is that
male urine contains less DNA than female urine.
Urine can also be identified using the Rapid Stain Identification test (RSID TM ) and is
developed to detect the presence of the urine specific Tamm-Horsfall protein (TPH).
The detection limit of this test is 5µL of human urine, and takes about 15 minutes to
give a result.
3.4.4 Sweat
Until now no genes have been described that are truly specific to sweat.
Nevertheless one study showed that it is possible to identify sweat using the G-81
monoclonal antibody and an ELISA technique 2 .
3.5 RNA as a tool for evidence identification
Most emerging techniques used for body fluid identification, discussed above, are
dealing with RNA. Unlike DNA, the transcript, RNA has not been extensively used in
forensic science. The potential of RNA so far has been underestimated. RNA was
notorious for its allegedly rapid post-mortem and in vitro decay, making it less useful
in forensic investigations. However nowadays new RNA technologies are developed
and several studies show that RNA can be detected after a long time 14,20 .
Nevertheless the environmental conditions play a major role. The review by Bauer 21
in 2007, described three examinations RNA could be used for. First diagnosis of the
cause of death, second determination of the age of wounds and injuries, and last
identification of body fluids. The main problem with these examinations are the
unpredictable conditions forensic stains are exposed to. In order for RNA to be useful
in crime scene investigations it is necessary to know more about the degradation
process, furthermore it is important to know what storage conditions are preferred for
crime scene samples. Both aspects will be discussed below for mRNA and
microRNA.
3.5.1 mRNA
Setzer et al 20 performed a study to gain insight into the process of body fluid specific
RNA degradation. The mRNA genes used for this study were: PBGD and SPTB for
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