Is DNA extraction from saliva a real alternative to using blood samples?
Nobody doubts that blood is a consistent and reliable source for obtaining DNA and carrying out genetic analyzes, but we cannot ignore the complexity associated with handling this type of sample: dedication of specialized personnel to obtain the specimen, the Invasiveness of the test for the patient, the complex handling of the samples and the special transport and storage conditions they require to avoid degradation.
All these drawbacks could be smoothed out by finding an equivalent source of genetic material, which in turn would facilitate the collection and stabilization of the sample’s DNA under ambient conditions.
Is it possible to substitute blood for other types of samples that offer these advantages while maintaining the quantity and quality of DNA?
Absolutely yes. A simple saliva sample can offer the same performance, while reducing the complexity of sample handling.
Why Use Saliva Instead Of Blood For Dna Extraction
When it comes to genomic material, the DNA obtained from saliva must yield to the same extent as that obtained from a blood sample. Where is the difference? In the enzymes and / or bacteria naturally present in saliva, which can alter and degrade that genetic material.
To avoid this problem, there are specific kits ( DNA saliva collection kits ) that include preservatives to keep DNA integrity intact.
There are several studies that demonstrate that DNA extracted from saliva yields results equivalent to that obtained in blood samples in techniques such as PCR, SNP, genotyping, microarrays and NGS.
Obtaining a blood sample can be tremendously stressful and painful for the patient, and especially complicated in the case of children, the elderly, psychiatric patients …
Once the sample is obtained, another handicap arises, and that is the transport and storage of the same, needing to send with dry ice and at controlled temperatures and store them refrigerated and / or frozen.
In contrast, the use of saliva samples for DNA extraction allows us to:
- Simple sample collection and easy handling
- Non-invasive, painless to the patient
- Does not generate anxiety in patients, facilitating recruitment
- The sample is stable at room temperature , allowing transport by ordinary mail as well as storage without the need for refrigeration / freezing (this becomes especially relevant in the case, for example, of multicenter studies).
The reduction of costs when using saliva against blood, which has been demonstrated in various studies , impacts at different levels:
- Sample collection: The patient does not need to go to the medical center for collection. The costs associated with specialized personnel to perform phlebotomy are also avoided.
- Sample shipping: Shipping is done at room temperature, avoiding shipping charges on dry ice and reducing package size.
- Sample storage: the sample is stable at room temperature, avoiding costs associated with freezing / refrigeration
In conclusion, can saliva replace blood as a source of genomic DNA? Definitely yes. Samples for DNA extraction from saliva obtained with the appropriate kits not only offer the same performance as a blood sample, but a series of additional advantages that encourage it to become the reference method.