By Staff Contributor

DNA (Deoxyribonucleic acid) acts as the storage medium of genetic information. It serves as your blueprint, because it contains the necessary data to properly compose the micro-components of your body, like cells and RNA molecules. If used properly, your DNA can also be used to distinguish you from other individuals. This technique of studying DNA to identify an individual is known as Forensic DNA Testing.

Forensic DNA testing is being widely used to distinguish species through DNA samples. It is also being used by the government to solve crimes. Over the years, there have been different techniques developed in DNA testing that have greatly helped in detective work, specifically in identifying and exonerating people that might or might not be involved in a crime. To name a few, here is a list of some of the popular techniques used in this field. 

  1. Restriction Fragment Length Polymorphism (RFLP). This technique was one of the first applications of DNA testing in forensic science. A special kind of enzyme called a restriction enzyme is used to cut the DNA into pieces. The pieces are then sorted through gel electrophoresis. The resulting sequence will then be observed to identify whether the DNA is the same as another DNA source. Since RFLP requires relatively large amounts of DNA, this technique was easily replaced by other newer and more efficient techniques.

  1. Polymerase Chain Reaction (PCR). Unlike RFLP, PCR uses only small amounts of DNA and amplifies it for further testing. The DNA sequences used are of short repeating patterns called VNTR (variable number of tandem repeats), which can range from 4 to 40 nucleotides in different individuals. One set of VNTR loci are inherited from the mother and one set from the father. The genes are amplified using PCR, and then run through electrophoresis. The position of the two bands on the electrophoresis gel depends on the exact number of repeats at the locus. Three VNTR loci from suspects, along with the DNA from the scene, are run through PCR amplification, and then through electrophoresis. This process gives six bands, which can have common bands for some individuals, but the overall pattern is distinctive for each person. 

  1. Short Tandem Repeats (STR). This is done by comparing the repeating patterns in two or more nucleotides. These repeated sequences should be precisely adjacent to each other. STR Analysis is a relatively new technique in forensics. This is mainly used in genetic fingerprinting of individuals.

  1. Amplified Fragment Length Polymorphism (AFLP). This is used to compare two organisms whose genome sequences are unknown. It only requires a small amount of genomic DNA to produce highly unique DNA fingerprints. It has been widely used to differentiate closely related organisms like fungi, animals and plants. It has also been used in criminal and paternity tests. 

  1. Y-chromosome (Y-STR) Analysis. This observes the polymorphic region in the Y-chromosome. Since Y-chromosomes are inherited from the father, Y-STR Analysis has been used to identify males who share the same father.

Forensic DNA Testing is an important innovation in the field of criminology and science. It has many applications and has helped society solve various mysteries that happen everyday.