For these DNA tests to work, it is essential to provide a high-quality biological sample. In most cases, laboratories ask participants to provide saliva samples. And this choice is not random. Indeed, the salivary sample has numerous advantages, making it the preferred choice for both laboratories and participants.
The simplicity of saliva: Non-invasive and easy to collect
One of the main advantages of a saliva sample is its simplicity. Unlike other methods, saliva collection is non-invasive and does not require any specific medical expertise. Participants only need to spit into a tube or rub a buccal swab inside their cheek. This simplicity makes the process accessible to everyone, regardless of age or health status.
A treasure trove of genetic information
In addition to its ease of collection, the saliva sample is valuable due to the richness of genetic information it contains. Saliva contains buccal epithelial cells that hold DNA. This means that the saliva sample can be used for paternity tests, genetic comparisons, and even to explore your ethnic origins. It provides a window into your genetic heritage that can answer many questions.
Long-term preservation and easy shipping
Another advantage of the saliva sample is its ability to be stored for long periods without significant DNA degradation. This means you can take your time to send your sample to the laboratory without worrying about genetic information deteriorating. However, it is generally recommended to send the sample within three months of collection to ensure the best results.
Discreet and cost-effective shipping
Finally, the saliva sample can be sent to the laboratory in a light, discreet, and cost-effective manner. You can simply slip it into a standard envelope without having to declare its contents for customs. This not only reduces shipping costs but also ensures that your shipment remains discreet and arrives quickly in the hands of genetic experts.
Other DNA Sample Options
While the saliva sample is often preferred for its simplicity and genetic quality, there are also other types of samples that can be used for DNA tests. These samples, considered more discreet, differ from saliva collection in that they can sometimes be collected without the person's knowledge.
Most laboratories conduct checks and, in some cases, may require confirmation of the participants' consent.
Privacy and individual rights remain a priority in the field of DNA testing. If you are considering using one of these more discreet methods, it is essential to ensure that you follow all applicable procedures and regulations.
Genetic Extraction
Genetic extraction is a crucial step in the process of conducting a DNA test. When a laboratory receives a biological sample or a carrier, such as a toothbrush or a buccal swab, the first step is to extract DNA from that sample.
DNA, containing the individual's genetic information, is found within biological cells. To obtain this valuable data, laboratory technicians use various chemical and biological methods to break the cell membranes and release the DNA. Once extracted, the DNA is purified and prepared for genetic analysis, enabling the establishment of an accurate genetic profile.
This step is essential for obtaining reliable and accurate results in DNA tests, whether it is determining family ties, exploring ethnic origins, or revealing genetic predispositions.
Indeed, the reliability of DNA extraction depends largely on:
The type of sample
Its storage conditions
Each biological sample presents its own challenges in terms of DNA stability. Samples such as blood, saliva, or fresh semen, when correctly collected and stored, generally offer excellent DNA quality, ensuring reliable results.
In contrast, older samples stored in inadequate conditions or subjected to extreme temperatures have an increased risk of DNA degradation. Additionally, some samples, like bloodstains on tissues, may contain inhibitors that complicate DNA extraction, reducing result reliability.
Similarly, samples contaminated by bacteria, fungi, or other agents may not provide enough genetic information to establish a clear DNA profile.
Therefore, it is essential to consider, when conducting a DNA test:
The nature of the sample
Its age
Its storage conditions
To ensure result accuracy. In some cases, it may be necessary to collect a new sample to obtain reliable genetic data.
In the following list, we present these different sample options, categorized based on their success rate and potential use for DNA extraction. Each of these samples has its particular characteristics, making them suitable for different DNA testing scenarios and needs.
Success Rate of DNA Extraction: 90% or More
Blood/Saliva on Filter Paper: These samples are collected on filter paper, a matrix, or a compress, preferably dated within 60 days. DNA can be extracted from dried blood or saliva stains for analysis.
Blood: Samples of fresh liquid blood stored in tubes with EDTA BD Vacutainer can provide a high success rate for DNA extraction.
Saliva: DNA can be extracted from saliva samples stored in tubes, preferably with preservatives, which help preserve the DNA.
Semen: DNA can be obtained from a frozen vial (e.g., from a sperm bank), a fresh swab, or semen on a fabric.
Mucus/Sputum: Generally obtained on a support such as a tissue, paper towel, or napkin.
Hair: DNA can be extracted from hair with visibly present roots, and it is recommended to provide 7 to 10 strands.
Toothbrush: After drying for 30 minutes, toothbrushes can be used to extract DNA for analysis.
Success Rate of DNA Extraction: 60% to 90%
Blood Stain on Fabric: DNA can be extracted from bloodstains on various types of fabrics, including bandages, gauze, tissue paper, towels, or clothing.
Diabetic Test Strips: It is recommended to use multiple strips to increase the chances of successful DNA extraction.
Cotton Swab: DNA can be obtained from earwax collected with cotton swabs.
Fetal Demise: A reference sample from the mother is required for cases of fetal demise for DNA analysis.
Nails: Pieces of fingernails or toenails (5 to 10 recommended) can provide DNA for testing.
Muscle/Organ Tissue: Non-embalmed samples are strongly preferred for DNA extraction.
Saliva Stain on Fabric: DNA can be extracted from saliva stains on fabrics such as gauze, tissues, sheets, or clothing. It is important to indicate the stain area.
Sperm Stain on Fabric: Similarly to saliva stains, DNA can be extracted from sperm stains on fabrics by indicating the stain area.
Umbilical Cord: Preferably dried, with a reference sample from the mother required.
Unknown Stain on Fabric: For biological stains of unknown origin on fabric, DNA extraction can be attempted. It is important to indicate the stain area.
Cigarette Butts: It is advisable to use multiple cigarette butts to increase the chances of DNA extraction.
Dental Floss: Dental floss should not be touched with fingers before submission.
Straw: Straws should be air-dried before being packaged for DNA analysis.
Tampon/Feminine Pad: Note that some feminine pads may not provide viable DNA due to the materials used.
Success Rate of DNA Extraction: 60% or Less
Chewing Gum: Sugar-free chewing gums are preferred for DNA extraction.
Chewing Tobacco: The contents should be sealed in a plastic bag, preferably dated within the last 3 days.
Sweat on Clothing: Items such as hats, caps, or bandanas can be used if stains are apparent.
Comb/Brush: The entire comb or brush with debris can be used for DNA analysis. The presence of hair increases the chances of successful extraction.
Condom: The entire condom, including the inside and outside, can be tested for DNA.
Envelope Flaps/Stamps: Envelope flaps or stamps licked before sealing can be used for DNA analysis.
Jewelry: Items such as rings, watches, necklaces, etc.
Razor (electric, disposable): The entire blade with hair can be submitted for DNA extraction.
Soda Can/Drink Glass: Submitting the can or glass is preferable to self-sampling using cotton swabs for DNA analysis.
Success Rate Based on Sample Type
Bone: Preference for the femur, humerus, or metacarpal (thumb bone).
Teeth: Preference for molars.
Feces: Contents in a sealed plastic bag, sent with ice packs or dry ice.