FYI: Testing DNA


THE Philippine National Police (PNP) dropped a bombshell on Monday when it said that the body that was found in a river in Nueva Ecija was not Reynaldo de Guzman based on comparative results of DNA tests on the victim and on his supposed parents.

READ: Body in Nueva Ecija not Reynaldo de Guzman based on DNA test–police

De Guzman, 14, was the friend of Carl Angelo Arnaiz, a 19-year-old, who was killed in an alleged shootout with Caloocan police after he was positively identified as the robber by a taxi driver whom he victimized last August 17.

The use of DNA testing has become an integral part of criminal investigations because of its high level of accuracy and reliability.

Below are some fast facts about DNA:

What is DNA?

A person’s DNA, or deoxyribonucleic acid, is simply defined as his or her own unique genetic makeup. It contains codes that carry information about a person’s traits and characteristics.

According to an article published by BBC Science, 99.9 percent of the DNA from two people will be identical. However, it is the 0.1% of DNA code sequences that make a person unique from others.

This 0.1% portion, called genetic markers, illustrates biological connections. Therefore, two people who are related to one another have similar genetic markers.

DNA test

There are many reasons for conducting a DNA test. The most common are:

Forensic testing — to help identify suspects or victims in a criminal investigation
Parental testing — to establish if someone is the biological parent of the child or vice versa.

Process of DNA testing

DNA testing is the most accurate technology to establish a biological relationship. Usually, DNA can be extracted from blood, saliva, semen, hair, nails and so on.

However, DNA sampling is usually collected by means of buccal (cheek or mouth cavity) swab.

The following is a simplified step-by-step process of conducting a DNA test:

1. A person’s DNA sample is collected. A long cotton swab is inserted into the inside of the mouth, and brushed against the cheek.

2. The swabs are sent to a laboratory, sealed in a sterile envelope to avoid contamination.

3. The sample DNA is extracted from the swabs and purified.

4. The extracted DNA is then separated and split at particular locations, and analyzed to create a DNA profile.

5. The DNA profile is studied and compared with another DNA to see if they match.

6. Results are usually released after a week or more, depending on the genetic testing lab.


DNA test results are highly accurate, with a reliability of 99.9 percent to 99.9999 percent.

Because DNA is unique for each person, the chances that two unrelated people have identical DNA profiles are less than one in one billion. YSABEL PADUA


“DNA Test Process.” Health Link DNA Accessed 11 September 2017.


“How does DNA testing work?” BBC Science 1 February 2013. Accessed 11 September 2017.



Please follow our commenting guidelines.

Comments are closed.