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Quantification of DNA, in dried blood, saliva tinged with blood in comparision with fresh blood for forensic
Kangan Manjunathan1, Radhika Manoj Bavle2, Mrinalini Menon1
1Department of Biotechnology, Sir M Visvesvaraya Institute of Technology, Bengaluru, Karnataka, India.
Abstract:
The important tenet of forensic science is personal identification based on DNA studies. The use of DNA has changed the specificity and sensitivity of victim identity tests associated with criminology, trauma, and natural disasters in Forensic Science. Blood is a proven source of DNA quantification for these analyses. The use of saliva, which can be acquired more easily in a simple and atraumatic method is gaining preference; as some of its advantages include - collection of larger sample numbers, easy replication of tests in duplicates and triplicates, and repetitions if advocated, can easily be performed. Though it yields a comparatively slightly lesser quantity of DNA, some of the samples - like dried blood and blood-tinged saliva, have the potential to be used in forensic sciences and provide a better result than simple saliva. Such samples are valuable sources of genetic material that can be utilized in crime and forensic investigations. The present study is one of few studies to be explored in this sphere as very few studies using blood-tinged saliva and dried blood have been conducted so far.
Aims And Objectives:
To determine if blood-tinged saliva or dried blood yields a good amount of DNA. To compare it with fresh blood samples for authentication.
Materials And Methodology:
The study groups: Group A - n = 20 normal blood samples, Group B - n = 20 of saliva-tinged blood samples and Group C - Dried Blood samples from the same subjects. DNA was isolated from these 60 samples using Xplorogen DNA isolation and extraction kit. The quality and quantity of DNA isolation were determined using a spectrophotometric technique using a Biospectrometer.
Results:
The extracted DNA was quantified and the yield was 83.3 ± 9.4, 55.1 ± 7.4, and 73.4 ± 8.7 μg/ml in fresh blood, dried blood, and blood-tinged saliva, respectively. Out of the 60 samples assessed, all 100% samples yielded a sufficiently good DNA content. Extraction from Blood tinged with saliva showed promising results when compared to dried blood and the levels obtained were closely comparable to whole blood (fresh).
Conclusion:
Blood is a standard sample for ample DNA yields in forensic studies. We conclude in this study, that blood-tinged saliva gives an equally good sample for utilization in DNA detection in those situations where such samples are traced (even at a later date) at the scene of crime, or mass disasters for forensic analysis.
