How to Do a DNA Test? Procedure, Samples and Uses
DNA testing is a laboratory procedure used to examine a person's genetic material for a specific purpose, such as identifying biological relationships, investigating genetic conditions, or studying ancestry. The exact procedure depends on the type of DNA test being performed.
How Is a DNA Test Done?
Most DNA tests follow a simple sequence: sample collection → laboratory analysis → interpretation of results. Genetic testing may use blood, saliva, cheek cells, or other tissue samples.
Step 1: Choose the Type of DNA Test
First, the appropriate test is selected according to the purpose. Common types include:
- Paternity testing: Used to assess a biological parent-child relationship.
- Genetic testing: Used to look for particular genetic variants or changes.
- Ancestry testing: Used to estimate genetic ancestry and identify potential genetic relatives.
- Forensic DNA testing: Used to compare DNA profiles for identification.
Step 2: Collect the DNA Sample
A DNA sample can be collected in different ways depending on the test. A cheek swab is commonly used because cells from the inside of the cheek contain DNA. Blood and saliva are also used for many genetic tests.
For a cheek-swab test, a special swab is rubbed against the inside of the cheek to collect cells. The sample is then placed in the appropriate container and sent to the laboratory according to the testing instructions.
Step 3: Laboratory Analysis
The laboratory extracts DNA from the collected cells and analyses the genetic material using techniques appropriate for the particular test.
For relationship testing, laboratories compare selected genetic markers between the people being tested. For medical genetic testing, the laboratory may look for specific changes in genes, chromosomes, or other parts of the genetic material.
Step 4: Receive and Interpret the Results
After laboratory analysis, the results are provided in a report. The meaning of the result depends on the type of DNA test.
For medical genetic testing, results may need to be interpreted with a healthcare professional or genetic counselor because a genetic variant does not always mean that a person has, or will definitely develop, a particular disease.
How Is a DNA Paternity Test Done?
A paternity DNA test commonly compares DNA from the child and the potential biological father. A sample from the mother may also be included. Cheek swabs are commonly used to collect DNA samples. The laboratory then compares genetic markers between the samples.
For a test intended for legal purposes, the collection process must follow the requirements of the relevant testing facility and jurisdiction. A simple home test may not have the chain-of-custody documentation required for court use.
Can You Do a DNA Test at Home?
Some direct-to-consumer DNA tests allow people to collect a cheek-swab or saliva sample at home and mail it to a laboratory. The company then provides the results through a report, website, or app.
However, an at-home test is not necessarily equivalent to a medically supervised or legally documented test. If the result will be used for a medical or legal decision, use an appropriate professional laboratory and follow the applicable requirements.
Is a DNA Test Painful?
A cheek swab is generally non-invasive and does not require a needle. Blood-based testing involves a routine blood draw. The preparation and risks depend on the particular type of genetic test.
DNA Testing: Simple Process
Frequently Asked Questions
What sample is used for a DNA test?
Depending on the test, samples can include blood, saliva, cheek cells, hair, skin, or other tissues. Cheek swabs are commonly used for many DNA tests.
How is a DNA sample collected from the cheek?
A special swab is gently rubbed against the inside of the cheek to collect cells containing DNA.
How long does a DNA test take?
The turnaround time varies by test and laboratory. Some consumer DNA tests may return results within a few weeks, while other tests can take longer.
Can a DNA test establish paternity?
Yes. A DNA paternity test compares selected genetic markers between a child and a potential biological father to assess biological parentage.
Conclusion
DNA testing involves collecting a suitable biological sample, analysing DNA in a laboratory, and interpreting the resulting genetic information. A cheek swab is a common and simple way to collect DNA, but the exact procedure depends on whether the test is for paternity, medical genetics, ancestry, or another purpose.