A DNA (Deoxyribo Nucleic Acid) test is the scientific matching of genetic profiles of unidentified or dead person with those of identified persons (dead or living). Besides identifying people, it can be used to diagnose or rule out suspected genetic disorders, predict risks for specific conditions, or gain information that can be used to customize medical treatments. Genetic tests can also be carried out on plants and animals to establish their origins and diagnose genetic disorders.
Types of DNA tests
The following are types of DNA tests that can be carried out.
a. DNA Paternity test
Paternity test determines whether a tested man is the biological father of a tested child. The child’s DNA pattern is compared to that of the alleged father to check for evidence of inheritance which is the proof of a biological relationship. In a standard DNA paternity test, the tested parties include child, father and mother. The mothers’ participation helps to exclude half of the child’s DNA leaving the other half for comparison with the alleged fathers DNA. However, a paternity test can be performed without the participation of mother and the results will still be equally conclusive.
b. DNA Maternity test
Determines whether a tested woman is the biological mother of a tested child. This test can be used to prove biological for example resolve situations where mothers or hospital staffs suspect that a baby mix up occurred in the nursery.
c. Family relationship testing
This determines whether individuals are related. These tests include; siblingship test, Avuncular (uncle-aunt test), and grand parentage.
d. Identity DNA Profiling
Private individuals may also choose to obtain records of their DNA profiles in case identification is ever needed. This is so as to;
- To safeguard the rightful heirs and ensure that they will inherit your estate through the exclusion of false claims on your inheritance.
- To avoid expensive exhumations if your DNA profile may be required in the future.
- As a precaution for any possible future identification/verification requirements e.g., in cases of kidnapping, accidental death, act of terrorism, etc.
e. Forensic DNA testing
This can be useful in:
- Linking unsolved crimes.
- Finding a suspect in criminal situations such as rape and incest.
- Identification victims of mass fatality disaster such as terror attacks, fire and natural disasters.
- Identification of missing persons for example individuals in mortuaries who cannot be identified by physical means.
How a DNA test is carried out
A typical DNA test follows the following procedure.
a. Sample collection
This can be any bodily fluid or hair from a person, as they all carry DNA. The most common, and least invasive sample taken is a swab of the inside of your cheek.
b. Lyse cells
This process will break down the membranes of the cells. Typically, performed by adding an enzyme to a solution containing the DNA sample.
There are multiple ways to separate DNA. However, the most common is a process called electrophoresis. This method uses an electric field to sort molecules in a sample. The unique molecular structure of DNA forces it away from the rest of the sample.
A process called PCR is used to generate copies of the DNA. These copies are then be tested for genetic markers.
Testing is the finding of genetic markers in the DNA that identify relationship. There are thousands of known genetic markers, but a relationship DNA test reports on 16 to 21 specific genetic markers that can prove a genetic relationship.
Now that markers have been obtained, they can be matched against an unknown DNA sample. This will help to show if the unknown is the same person as the DNA donor. The results are usually given in the form of percentages, with the lowest being 0% and the highest 99.99%.