Types of DNA testing
A few types of relationship testing
PCR is currently the most popular type of testing currently available. It involves copying the original DNA sample into hundreds of thousands or millions of copies of the original. It is copied by using thermo-cycling. This is the process of heating and cooling the original sample forcing it to replicate. This process is continued until enough copies are available for running testing in a gel. The advantages of PCR are that it is fast efficient and can be completed using very small DNA samples. It is relatively cheap, and easily completed. There are more than forty one different DNA marker kits that can be completed using PCR. It is used widely in law enforcement to catch criminals, and for DNA identification such as paternity testing. The true sole problems with PCR testing is it is not a very powerful test, and that it is subject to contamination, as the contaminate DNA will also be replicated.
RFLP, this type of testing does not involve replication. For this reason it requires a larger amount of DNA perform the test. This test involves breaking the DNA apart at different known locations. A solution is used to break the DNA apart. The different segments of DNA are put into a gel with a direct current voltage running through it. The fragments are drawn across the gel at different speeds biased on the weight of, or quantity of information in the DNA. Being that everyone's DNA will have different genetic information in each segment, everyone's DNA will travel at a different speed. This can compare father's and mother's DNA to a child's DNA in this fashion, as the genetic information that came from each should travel at the same speed as the child's DNA. The advantages of this test are that it is extremely powerful when compared to PCR. It would take seven markers of PCR testing to complete with the power of one location of PCR testing. RFLP is widely used when PCR cannot answer a question of paternity. The problems with RFLP is that it is slow, it takes about 2 weeks, it requires a large sample of DNA, so it is not good for the deceased, it is expensive, and very few laboratories still have the ability to perform this testing. Y chromosome testing, this testing is used to find male linage over generations. It is used when a sample from the father is not available in paternity testing, or it is also used sometimes in criminal cases. Some other uses for Y chromosome testing are Grandparent, and family reconstructions. The advantages of this testing are that it can be determines if someone is in the same family, and prove male linage to people such as Grandpas and uncles on the father side. The big disadvantage to this test, it cannot prove how the tested parties are related, just show that they are somehow related on the father's side.
Mitochondrial DNA testing, in simple terms is the direct opposite of Y chromosome testing. It carries the same problems as Y chromosome, and also the same advantages, with one extra advantage. Mitochondrial DNA is also found in hair.
About the Author
Scott is the Asia Area Manager for Paternity Testing Corporation.
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