Our 12plex failed in cases 2 and 3 as a screening tool (it could
not identify semen and vaginal secretion). In case 2 it only
failed because we limited the number of semen markers to one
seminal fluid and one sperm cell marker. However the application
of the 12plex to the 33 challenging forensic casework
samples also revealed its value in forensic casework. The 12plex
can distinguish between blood and menstrual blood, indicate
contents of further body fluids (Table 1, case 4) and is a useful
method to confirm the presence of azoospermic semen (Table 1,
case 5).
4. Conclusions
The RNA/DNA co-extraction strategy is a useful tool to identify
donor and source of origin of a body fluid stain.
mRNA data should always be interpreted together with the
results from the presumptive tests and the DNA analysis.
mRNA results should be confirmed by doing replicate PCRs
or/and an additional body fluid specific multiplex analysis.
Especially negative mRNA results should be interpreted carefully
as intra- and inter-individual variability has to be kep