RNA was first introduced into forensic literature in 1984 when post-mortem RNA synthesis was described. It took several more years until another study was conducted introducing gene expression analysis, and even then it wasn't until after crucial advances were made when gene expression analysis was adopted by forensic laboratories and further applications using RNA were explored. When these applications were tested, the potential use for RNA in the identification of body-fluids and wound age estimation was uncovered. Today, body-fluid identification via specific mRNA quantification is an established standard technique in many forensic laboratories.
Even though successful mRNA recovery and profiling from even aged samples has been demonstrated, mRNA stability and susceptibility to degradation has always been an issue for mRNA based gene expression analysis, and impaired mRNA integrity impacts the reproducibility of the results. This was expected to be especially problematic for forensic routine applications using mRNA, because biological stains from casework are often met with challenges such as moisture, UV light, temperature, etc., which would potentially degrade mRNA beyond usability. miRNA profiling has been shown to have potentially serious advantages over mRNA profiling. Due to their small size of about 22 nt, mature miRNAs are much more stable than mRNAs, which makes them decidedly less susceptible against fractionation by chemical or
physical strain. MiRNA profiling also has greater discriminatory potential than mRNA profiling, and it is believed that miRNA could even outperform mRNA profiling when it comes to identification of mixed and/or heavily environmentally challenged stains.
Initial studies clearly show the potential of miRNA
profiling for forensic science. In a study conducted in 2009, it was demonstrated that miRNA can be extracted from forensic samples. Using blood, saliva, semen, vaginal secretions, and menstrual blood, they created body fluid specific assays consisting of two differentially expressed
miRNAs per body fluid which they used to successfully identify and
discriminate each. Menstrual blood could clearly
be distinguished from non-menstrual blood and even sperm-free
semen could reliably be detected.
Although more research is needed before using the analysis in the field, miRNA-profiling may become a very promising tool
for forensic analysis
Source:
https://ac.els-cdn.com/S0379073810003312/1-s2.0-S0379073810003312-main.pdf?_tid=df0b85de-
b07b-11e7-9d9a-00000aab0f27&acdnat=1507943352_b92987412bf86dfc27c427e23edccfe2
Nice summary of an exciting topic.
ReplyDeleteThis is very interesting! I just wrote my blog this week over the use of RNA for an estimation of the post mortem interval. Although, I did not agree with the studies conducted in the article I discussed, I do think when it comes to determination of body fluids, it could very well become an important tool used someday. The only problem, like you stated, is how rapid RNA degrades.
ReplyDeleteIt is amazing the vast applications that molecular techniques and tools have. They span so many fields and have led to huge strides in our communal knowledge. The application of things like mRNA quantification that you described and miRNA extraction is amazing. Just a handful of years ago, these things were unimaginable and now the protocols have been optimized and distributed widespread to where as you mentioned, many forensic labs are using these methods for analysis on a daily basis.
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