A common sight on television, in books and even in the courtroom, DNA blood testing has become one of the standards of ultimate proof for many in America. However, just what DNA blood testing is can be a rather difficult and convoluted topic to explain without over simplifying things. The basics of the process though, are easy enough to understand.
DNA is an acronym for deoxyribonucleic acid. This material is found in every cell in the human body, and it is what determines the physical qualities of a person. Hair and eye color, height, bone density and thousands of other factors. It is, essentially, the blueprint for the human body.
Just as every single person is unique, so to is every person's DNA completely unique. This means that if a sample of a person's DNA is taken that it can be compared to other DNA for purposes of identification. This is used at crime scenes, as well as in paternity testing.
DNA can be found in any part of the body, from hair to saliva. Blood samples are often taken because blood contains a large amount of DNA. Additionally, since blood comes from the interior of the body, it will have fewer factors to interfere with the harvested DNA. This cannot be said of skin samples, which may have come into contact with contaminants, or of samples taken from saliva, which may be influenced by food.
Once the blood sample is taken, the DNA chains are examined by experts. If a certain condition is being tested for, than sections of the DNA chain will be scrutinized for markers of the condition or defect. If the test is forensic, than the DNA sample taken from the blood will be compared to another DNA sample taken from a victim, or from a crime scene, to see whether or not the person sampled can be placed at the scene of the crime.
While DNA testing is a great boon, especially to police officers, it is not flawless. DNA blood tests most often require a sample to be in good condition before it is tested and compared. While the sample taken from a volunteer is perfect, samples found elsewhere and preserved are often degraded by heat, wind or just time. As such, DNA blood testing may only be able to build a partial profile of the person who was at a crime scene, and as such is just one more tool and not a final answer.
- Image by Flickr.com, courtesy of Kevin Dooley