DNA testing

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DNA testing in forensic sciences

The uniqueness of DNA sequences of every individual had paved way for great progress in forensic analysis. Earlier though it was easy to exclude an individual from the suspects list, it was a very complicated issue for the forensic personnel to provide evidences to support the inclusion of a suspect into the convicted list. This resulted in many criminal cases going unanswered. However the advances in technology of DNA testing, sequencing and safeguarding had alleviated this difficulty. The inconsistencies in DNA polymorphisms of two different individuals enables forensic scientists to conclude with strong evidence that the DNA from a suspect and the DNA obtained at the place of crime are the same.


Until DNA testing was familiarized, fingerprinting was the only technique used to provide evidence against convicted individuals. DNA testing had now proved not only revolutionary in the field of forensic sciences, but had also provided very unique, strong and accurate evidences to support the cases of forensic personnel. A total of 13 DNA regions or loci, which vary from person to person, are scanned and the data is used to create the DNA profile of an individual person. The possibility of another person having the same DNA profile for all the 13 regions are around 1 in 350 million. This fact goes a long way to prove the use of DNA testing in forensic sciences to identify the suspect.


While major uses of DNA Testing such as ancestral tracing, paternity identification etc call for identifying similarity between DNA samples of two individuals, DNA testing in forensic sciences is all about identifying unique characteristics of DNA sample which would differentiate it from another individual’s sample. The two major DNA polymorphisms used for such uniqueness identification of forensic sciences are VNTRs and STRs.


VNTR – abbreviated as Variable Number of Tandem Repeats – are DNA regions in which a short sequence, usually 8 to 35 bases in length is repeated in tandem 100 or more times. The exact number of repeats differs considerably between two different persons and hence this proves to be a strong evidence for variability. The probability of a random person’s VNTR profile matching that of the suspect had generally been observed to be 1 in 100 billion or so.


On the other hand, STRs provide sequences with highest degree of polymorphism which prove to be highly valuable for forensic sciences. STRs are found to be highly advantageous compared to VNTRs basically because of their ability to amplify rapidly in days. It means that the DNA of a suspect obtained from a very small trace sample can be increased to a huge amount that would facilitate its ready examination. STRs also tend themselves to automation and readymade kits are now available in which as much as 16 loci can be analyzed simultaneously. Such easiness of analysis had made STRs highly attractive to forensic sciences than the VNTRs.


Today reputed organizations have numerous branches across the country and provide same quality of services whether it be DNA testing in Colorado or at any of its branches across various states. Thus with such extra ordinary advancements in the technology of DNA testing and easy availability of testing centers, it has become easy and quick for forensic professionals to provide strong supporting evidences to include convicts into the cases and also had increased the ease of releasing an innocent individual from the case.


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