Yes, saliva contains DNA. In fact, saliva is a reliable source for DNA extraction used in a wide variety of genetic applications. While the amount of DNA can vary between individuals, it yields virtually the same amount of DNA per volume and the same DNA quality as other sources.
Where Does the DNA in Saliva Come From?
The majority of DNA found in saliva originates from white blood cells, also known as leukocytes. However, it's crucial to understand that saliva is a complex mixture. It also contains DNA from:
- Epithelial cells: These cells line the inside of your mouth.
- Bacteria: Your mouth is home to a vast number of bacteria, and their DNA is also present in saliva. This contaminating DNA can sometimes affect the accuracy of DNA analysis.
One milliliter of saliva can contain a mixture of DNA from approximately 4.3 x 105 epithelial cells, 1.36 x 105 leukocytes, and 1.7 x 107 bacteria.
Uses of Saliva DNA
Saliva's DNA content makes it a valuable tool in various fields:
- Forensic science: Saliva left at a crime scene can be used for DNA fingerprinting.
- Medical diagnostics: Saliva DNA can be used for genetic testing and disease diagnosis.
- Paternity testing: Saliva samples can be used to establish paternity.
- Genealogical research: Saliva DNA provides information for ancestry testing.
Important Considerations
- DNA concentration: The concentration of DNA in saliva varies among individuals. Some samples may contain very little DNA.
- Contamination: Saliva can be easily contaminated with other DNA sources, impacting the accuracy of the results.
