Before a DNA test can be performed, a suitable biological sample needs to be collected. The sample contains cells from which DNA can be extracted and analysed in a laboratory.
For most modern DNA tests, sample collection is simple and does not require a blood draw. A cheek swab, also known as a buccal swab, is one of the most common methods used because it is quick, painless, and easy to collect.
However, different situations may require different types of samples.
In this guide, we'll explain the most common ways DNA samples are collected, what happens during collection, and what you should know before providing a sample.
If you're interested in DNA and other laboratory investigations, you can explore available tests through AllAnalysis.
What Is a DNA Sample?
A DNA sample is biological material containing cells from which DNA can be extracted.
DNA is found in almost all cells in the human body. This means several types of biological material can potentially provide DNA.
For routine relationship testing, however, laboratories usually prefer samples that are easy to collect and provide reliable DNA.
The Most Common DNA Sample: Cheek Swab
A cheek swab is one of the most widely used methods for collecting DNA.
A sterile swab is gently rubbed against the inside of the cheek. This collects cells from the mouth that contain DNA.
The process is:
- Quick.
- Painless.
- Non-invasive.
- Suitable for children and adults.
- Easy to transport to a laboratory.
Once collected, the swab is packaged and sent to the laboratory for DNA extraction and analysis.
How Is a Cheek Swab Collected?
The exact instructions can vary between testing providers, but the general process is straightforward.
Step 1: Prepare the collection materials
A sterile DNA collection swab is provided.
You may also receive instructions about avoiding food, drinks, smoking, or chewing gum before collection.
Always follow the specific instructions supplied with your test.
Step 2: Open the swab carefully
The swab should be handled according to the provider's instructions.
Avoid touching the end of the swab with your fingers.
Step 3: Rub the inside of the cheek
The swab is rubbed firmly against the inside of the cheek for the recommended amount of time.
This collects cells from the surface of the mouth.
Step 4: Allow the sample to dry if instructed
Some collection kits require the swab to air-dry before it is placed into its packaging.
Follow the instructions provided with the particular kit.
Step 5: Package the sample
The swab is placed into the appropriate container or packaging and labelled according to the testing provider's instructions.
It is then sent to the laboratory.
Does DNA Sample Collection Hurt?
Cheek-swab collection is generally painless.
Unlike blood collection, it does not involve a needle.
This makes cheek swabs especially convenient for children, adults, and people who may be uncomfortable with blood tests.
Are Blood Samples Used for DNA Testing?
Yes, blood can contain DNA and may be used for genetic testing.
However, many modern relationship DNA tests do not require blood because cheek cells provide enough DNA for analysis.
Blood collection may be used in certain medical or specialised testing situations depending on the test being performed.
Can Hair Be Used for DNA Testing?
Hair can sometimes provide DNA, but it depends on the hair sample.
Hair with the root or follicular tissue attached is more likely to provide useful nuclear DNA than a hair shaft without the root.
Because hair samples can be more difficult to analyse than cheek swabs, you should contact the laboratory before submitting hair for testing.
Do not assume that any loose hair will automatically be suitable.
Can Saliva Be Used for DNA Testing?
Yes.
Saliva contains cells that can provide DNA.
Many DNA collection kits effectively collect DNA-containing cells from saliva or the inside of the cheek.
The exact collection method depends on the laboratory and the test kit being used.
Can Blood Stains Be Used?
Potentially, yes.
Blood contains cells with DNA, so a blood stain can sometimes provide a usable DNA sample.
However, old, damaged, contaminated, or poorly stored samples may present challenges.
If you have an unusual sample and want to know whether it can be tested, speak with the laboratory before sending it.
Can Tooth Samples Provide DNA?
In some circumstances, teeth can provide DNA.
This may be particularly relevant when testing biological material from deceased individuals.
However, tooth testing is more specialised than routine cheek-swab testing and should be discussed with a laboratory experienced in handling such samples.
Can Nail Clippings Be Used for DNA Testing?
Nail clippings may sometimes contain usable DNA.
However, the success of testing depends on the sample and the type of DNA analysis required.
If a cheek swab is available, it is usually a much simpler option for routine relationship testing.
What Happens After the Sample Is Collected?
Once the sample reaches the laboratory, several steps take place.
DNA extraction
DNA is extracted from the cells contained in the sample.
DNA profiling
The laboratory analyses selected genetic markers to create a DNA profile.
Comparison
For relationship testing, the profiles of the individuals involved are compared.
Statistical analysis
The laboratory evaluates how strongly the genetic evidence supports or excludes the proposed relationship.
Reporting
The findings are compiled into a laboratory report.
How Are Legal DNA Samples Collected?
Legal DNA testing requires more than simply obtaining a DNA sample.
The identity of each person being tested needs to be verified, and the collection process must be properly documented.
Depending on the circumstances, the process may include:
- Identity verification.
- Photographs.
- Controlled sample collection.
- Documentation.
- Secure packaging.
- Chain-of-custody records.
These procedures help demonstrate that the sample analysed belongs to the individual identified in the case.
This is important when the result will be used for immigration, court proceedings, inheritance, or another official purpose.
Can DNA Samples Be Collected at Home?
Some private DNA tests allow samples to be collected at home.
This can be convenient when the result is only needed for personal information.
However, a home-collected sample may not meet the requirements for legal testing.
If the result is intended for immigration, court, or another official purpose, arrange the appropriate legal collection procedure from the beginning.
How Can You Avoid Contaminating a DNA Sample?
Proper handling is important during DNA collection.
To reduce the risk of contamination:
- Follow the collection instructions carefully.
- Avoid touching the collection end of the swab.
- Use only the materials supplied or approved by the laboratory.
- Keep samples away from other people's biological material.
- Package samples exactly as instructed.
- Label samples correctly.
If you're unsure about how to collect a particular sample, contact the laboratory rather than improvising.
What Happens If There Isn't Enough DNA?
Sometimes a sample may not contain enough usable DNA for analysis.
This can happen because of poor collection, insufficient cellular material, contamination, or degradation.
If the laboratory cannot obtain a suitable DNA profile, you may be asked to provide another sample.
For a cheek-swab test, collecting another sample is usually straightforward.
Can Babies Have Their DNA Collected?
Yes.
DNA can be collected from babies and children using appropriate collection methods.
Cheek swabs are commonly used because they are non-invasive and don't require a needle.
Depending on the circumstances, a parent or legal guardian may need to provide consent.
How Should DNA Samples Be Stored?
Storage instructions depend on the type of sample and collection kit.
Cheek swabs may need to dry before being placed into their packaging, while other sample types may require different storage conditions.
Always follow the laboratory's instructions.
Incorrect storage can affect the quality of the sample.
Frequently Asked Questions
What is the most common DNA sample?
A cheek swab is one of the most common samples used for routine DNA relationship testing.
Does DNA collection hurt?
A cheek swab is generally painless and does not require a needle.
Can blood be used for DNA testing?
Yes. Blood contains DNA and can be used for certain types of genetic testing.
Can hair be used for DNA testing?
Sometimes. Hair with the root attached is generally more useful for nuclear DNA testing than hair without the root.
Can saliva provide DNA?
Yes. Saliva contains cells that can provide DNA.
Can nail clippings be tested for DNA?
Sometimes. The suitability depends on the sample and the type of testing required.
Can I collect a legal DNA sample at home?
Usually, you should follow the controlled collection procedure required for legal testing. A standard home-collected sample may not be accepted for official purposes.
What happens if my sample fails?
The laboratory may request another sample if there isn't enough usable DNA for analysis.
Final Thoughts
DNA sample collection is usually much simpler than people expect.
For most routine relationship tests, a cheek swab is all that is needed. It provides DNA-containing cells without the need for a blood draw and can be collected quickly and painlessly.
Other biological materials, including blood, hair, saliva, teeth, and nail samples, may also provide DNA in certain circumstances. However, their suitability depends on the type and condition of the sample.
If your DNA test is for personal information, home collection may be available. If the result is intended for immigration, court proceedings, inheritance, or another official purpose, make sure the sample is collected using the required legal procedures.
If you're looking for DNA and other laboratory testing services, explore the available tests through AllAnalysis.
You can also read more DNA and laboratory testing guides on the AllAnalysis blog to learn more about DNA testing and what to expect before getting tested.
