DNA analysis has revolutionized forensic science, providing invaluable tools for crime resolution, victim identification in disasters, and establishing familial relationships. This article offers a comprehensive review of the role of DNA in forensic science, examining its structure, function, and the advanced techniques used for its analysis.
Composition and Function of DNA
DNA, or deoxyribonucleic acid, is the cornerstone of genetic information in all living organisms. Composed of nucleotide triphosphate molecules, DNA is organized into a double helix structure discovered by Watson and Crick in 1953. The nitrogenous bases (adenine, guanine, cytosine, and thymine) form essential pairs for genetic coding. The human genome, consisting of over 3 billion base pairs, contains genes that regulate protein synthesis and vast regions of non-coding DNA crucial for forensic identification.
DNA Analysis Techniques
DNA Extraction
DNA extraction from biological samples is performed through cell lysis, followed by centrifugation and purification. This technique prepares the DNA for further detailed analysis and is essential to ensure the integrity of the samples.
Polymorphisms and Sequencing
Forensic techniques focus on identifying genetic variations such as single nucleotide polymorphisms (SNPs) and tandem repeats (VNTRs and STRs). DNA sequencing, though not common in all forensic aspects, is crucial for detailed analysis of mitochondrial DNA and other specific genetic markers.
PCR and Electrophoresis
Polymerase chain reaction (PCR) amplifies DNA segments for analysis, while electrophoresis separates these segments by size, facilitating DNA profiling. Capillary electrophoresis has enhanced the speed and accuracy of this process.
Blotting and LCN Analysis
Blotting techniques, such as Southern and Western blot, are used post-electrophoresis for specific detection of DNA sequences or proteins. Low copy number (LCN) DNA analysis enables the generation of DNA profiles from minimal amounts of genetic material, increasing the sensitivity of traditional forensic methods.
Forensic Applications of DNA
Criminal Identification and Paternity
Since its introduction in the 1980s, DNA profiling has been pivotal in identifying criminals, disaster victims, and in paternity testing. The ability to compare genetic profiles has solved unresolved cases and exonerated the innocent.
DNA and Mass Disasters
In mass disaster events, DNA has been essential for identifying human remains, helping to close painful chapters for many affected families.
DNA Databases
DNA databases, like the NDNAD in the UK and CODIS in the US, have enabled rapid comparisons of DNA profiles, facilitating crime resolution and suspect identification through samples collected at crime scenes.
Challenges and Ethical Considerations
The increasing sensitivity and precision of DNA techniques raise ethical concerns, including privacy, consent to store genetic information, and risks of contamination and interpretation errors. Legislation has evolved to address these challenges, ensuring that the use of DNA in forensic science is handled with utmost integrity and respect for individual rights.
Conclusion
Forensic DNA science has significantly advanced since its inception. Though it faces ethical and technical challenges, its role in criminal justice and person identification remains irreplaceable. As technology evolves, so does the accuracy and efficacy of DNA analysis, promising future improvements in crime resolution and justice administration.
Jeffreys, A J. Thein, S L. Wilson, V. Individual-Specific Fingerprints of Human DNA. Nature. 1985, 316)6023), 76-79.
Watson, J D. Crick, F H. A Structure for DNA. Nature. 1953, 171, 737-738.
Findlay, I. Taylor, A. Quirke, P. et al. DNA Fingerprinting from Single Cells. Nature. 1997, 389(6651), 555-556.
Jackson, A. R. W, Jackson, J. M., 2011. Forensic Science. Essex: Pearson Education Limited.
White, P. C., 2004. Crime Scene to Court: The Essentials of Forensic Science. Cambridge: The Royal Society of Chemistry.
DNA Analysis. (s/f). Aboutforensics.co.uk. Recuperado el 10 de noviembre de 2021, de https://aboutforensics.co.uk/dna-analysis/
