Examination of Firearms Review: 2007 to 2010 - Interpol

for human blood by using antibodies that are specific for the human specific and
blood specific protein glycophorin A 7 .
3.2.2 Emerging and future techniques
New techniques which are developed for the detection of blood are aiming on the
identification of the body fluid, and are species specific as well. Most of the new
techniques deal with RNA analysis. The DNA from a cell’s nucleus is transcribed into
messenger RNA (mRNA), which in turn is translated into proteins. The proteins in a
cell determine its function, and therefore the protein makeup together with the RNAs
in a cell can disclose the tissue or fluid type we are dealing with. Because of the rapid
developments in DNA technology, the step towards the use of RNA technology is
straightforward. In 2004, Alvarez et al 8 revealed a method to isolate RNA and DNA
simultaneously from the same stain extract. This makes it possible to yield
information about the nature of the stain using RNA analysis, while DNA analysis of
the same extract can be used to individualize the sample. Juusola and Ballantyne 9 in
2005 proposed a multiplex reverse transcription-polymerase chain reaction (RT-PCR)
to identify different body fluids (blood, saliva, semen, and vaginal fluid). The RNA
tests to identify aimed at the genes for beta spectrin (SPTB) and porphobilinogendeaminase
(PBGD). Haas et al 10 found that positive results could be obtained from
stains that were up to 15 months old. Menstrual blood was detected by the presence
of the matrix metalloproteinase-7 (MMP-7) and MMP-11, Both proteinases are absent
from circulatory blood and menstrual-free vaginal swabs 11,12 . Zubakov et al 13 in 2008,
analyzed gene expression in aged bloodstains in order to find stable RNA markers,
which are highly expressed in blood, and have low expression in other fluids. They
concluded with nine possible markers 13 (CASP1, AMICA1, C1QR1, ALOX5APm
AQP9, C5R1, NCF2, MNDA, and ARHGAP26). Although all of the markers were able
to differentiate blood from semen samples, none of them could differentiate blood
from vaginal fluid because of the complex nature of vaginal secretions. In 2009,
Zubakov et al 14 used the nine markers mentioned above on old bloodstains, and
proved their effectiveness in freshly dried blood samples, and stains up to at least 16
years old. Because the age of crime scene sample can vary to a great extent it needs
to be proven that mRNAs intended for forensic use can be amplified successfully
under a wide range of sample conditions including aged samples.
Besides mRNA, microRNA (miRNA) can also be used for body fluid identification.
MiRNAs are non-protein coding molecules with important regulatory functions; many
have tissue specific expression patterns 15 . They are on average 22 nucleotides long
and have a stem-loop secondary structure, making them less prone to the
degradation process compared to mRNA. In 2009 Hanson et al 16 were the first to use
miRNAs for forensic body fluid identifications. Although no truly body fluid specific
candidates were identified (in the sense of being present in one body fluid and
completely absent in the other body fluids). They concluded that miR-451 and
miR-16 could be used to differentiate blood from semen, saliva, and vaginal fluid 16 .
cDNA can be produced from all RNA species within a sample, including mRNAs and
other small noncoding RNAs 16 . One advantage is, that when the miRNAs are
insufficient to identify the body fluid, mRNAs can be used from the same RT reaction
to help identify the body fluid. Furthermore the production of cDNA from total RNA
uses less genetic material from evidentiary samples, which is crucial when there is
little genetic material present. In this case 1ng of total RNA from blood, saliva, vaginal
fluid, and menstrual blood extracts and 5ng of total RNA from semen extracts were
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