DNA (Deoxyribonucleic Acid) profiling also known as DNA testing, Genetic Fingerprinting or DNA Typing is a technique used by Forensic Scientists to assist in identifying individuals on the basis of their own unique DNA profile. We say unique but hold fire; Ninety-nine point nine percent (99.9%) of human DNA is the same in everyone, meaning that only 0.1 percent of our DNA is unique! Each and every human cell contains approximately three billion DNA base pairs. Our unique DNA, represents 0.1 percent of 3 billion which amounts to 3 million base pairs. This is more than enough to provide a profile that accurately identifies a person. The only exception is identical twins, who have 100 percent identical DNA.
At a crime scene or DNA can potentially be found everywhere. DNA can be collected from a crime scene through the collection of all kinds of evidence including blood, semen, hair, skin and saliva. Scientists analyse DNA collected from crime scenes to try and find a ‘match’ with a suspect's DNA or vice versa.
The collection of DNA sampling is not only reserved for crime scenes but also for the identification of missing persons or disaster victim identification (DVI). DVI Experts at Scilife Solutions use different techniques to retrieve DNA from disaster victims but the main aim is always the same, to achieve a profile. Once the profile has been identified it can be used for example in the arduous task of tracing family through familial DNA matching if no other form of identification can be retrieved from the victim.
Historically DNA analysis required samples at least the size of a 5p pence. However, today's techniques can multiply the DNA, producing hundreds of thousands if not millions of copies from the tiniest amounts of evidence, such as the saliva from a cigarette butt. This approach is helpful for analysing poor-quality DNA in evidence samples collected from dirty or ‘busy’ crime scenes.
Generally speaking the most common method of collecting DNA samples from individuals is through the collection of buccal cells using buccal swabs (http://scilifesolutions.co.uk/category/7-CEP-Buccal-Swab-Kits.html) or by the collection of a blood sample using a blood collection kit (http://scilifesolutions.co.uk/category/42-Blood-Sample-DNA-Kit.html).
The most common products used today for the collection of samples are swabs such as the CEP swab and DNA Cards such as the Fitzco DNA Cards or Whatman FTA Cards.
