Introduction
Unless you are an identical twin, your DNA (deoxyribonucleic acid) is unique to you and you alone. Because of your DNA, you look the way you do, from your eye color to your height and body structure. DNA acts much like a fingerprint that allows scientists to determine who the DNA belongs to by comparing samples and looking for matching unique structures. The process of comparing these samples is called DNA testing.
Paternity Testing
Paternity testing is one of the most common forms of DNA testing. In this process the DNA of a potential father is compared to that of a child. For this to happen, first a DNA sample is taken from both the father and the child. DNA samples can come from hair, saliva, semen, body tissue, amniotic fluid or blood. Most commonly, paternity testing is done with blood drawn from the presumed father set against a sample from the child. The samples are then sent to a lab for restriction fragment length polymorphism (RFLP) testing. During RFLP, lab technicians look for similar base pairs in sections of the DNA that have a higher probability of being unique to each individual, but similar in paternal relationships. If a match is found, paternity is proven.
Prenatal and Genetic Testing
Prenatal and genetic testing is another form of DNA testing. In this procedure, a DNA sample is taken from the amniotic fluid of the unborn baby, or can also be taken from the blood of a child or adult. Once the sample is sent to the lab, scientists review the DNA for specific genetic markers or mutations that signify the potential for development of disease. According to Pathway Genomics, there are at least 90 different diseases that may be determined through genetic testing.
Forensic Testing
Another common reason that DNA tests are performed is for forensic testing. This is usually done to link a suspect to a specific crime. DNA testing for forensics can be done through RFLP testing, but can also be done through polymerase chain reaction (PCR). PCR tests can be done with a much smaller sample than an RFLP test, and can also be done with a sample that is quite old. This makes PCR tests perfect for helping to solve crimes. PCR tests are done by taking the sample and focusing on specific gene matches, instead of full base pairs. The DNA from a crime scene is copied over and over again to reveal a DNA profile. From that profile specific genes (such as the HLA DQ alpha gene) are isolated, which can then be matched to DNA samples on file.
