While a saliva DNA test can be misinterpreted, the chances of error are very slim, as long as it is conducted in an accredited laboratory. It’s a fair and important question, and the honest answer is that the test itself is scientifically reliable. It’s not the science that poses risk; it’s the process that poses risk. The accuracy and reliability of your results is affected directly by the quality of your samples, how they’re collected, how contaminated they can be, and the standards used in the lab. This blog details where mistakes can occur and how professional testing eliminates them.
How reliable are saliva DNA tests to establish paternity?
Answering your concern of can a saliva DNA test be wrong? when analyzed by a trained lab under the appropriate conditions, a saliva DNA test is extremely accurate. The most common method of saliva collection is a cheek swab, which is a swab that is placed in the lining of the cheeks. These cells have the full DNA found in the blood and a saliva DNA test is therefore as scientifically valid as a blood-based test if conducted properly. The accuracy is a function of the quality of the laboratory, not of the type of sample.
Cheek Swab Testing and Reliability.
Full nuclear DNA (genetic content is identical to blood) is found in cheek swab samples. A proper collection and laboratory processing of saliva DNA can yield paternity results of 99.9% or higher probability of inclusion and 100% conclusive exclusion. The accuracy of a sample cannot be determined by the type of sample; that is done in the laboratory with standards.
Are there times when a Saliva DNA Test can give an incorrect or inconclusive paternity result?
Yes, a saliva DNA test may be incorrect, but it is almost always a procedural error and not a scientific error. The DNA lies not. Errors usually stem from contamination, poor sample collection or insufficient DNA yield due to an inadequate swab. Knowing where errors come in can help to paint a picture of why there are accredited laboratory processes and why they are so important for result integrity.
Errors and Their Causes
| Error Type | Cause |
| Saliva DNA test false positive | Sample contamination from a third party’s DNA during collection |
| Saliva DNA test false negative | Insufficient DNA yield from a poorly collected or degraded swab |
| Inconclusive result | Low-quality sample due to eating, drinking, or smoking before collection |
| Misidentified sample | Labeling or handling error during collection or submission process |
| Chain of custody failure | Improper documentation making results legally inadmissible |
What are some factors that might influence the reliability of a saliva test?
There are several factors that can affect a saliva DNA test that can occur in the real world, before the sample ever gets to the lab. Understanding factors that can impact accuracy will allow you to see the purpose of the collection instructions and the importance of adherence to the instructions.
Sample Collection, Contamination, and Laboratory Quality
- If food or drink is eaten, drunk or smoked before swabbing, it will contain organic material that will dilute the buccal cells and thereby decrease the amount of DNA available for the lab to use.
- In-home testing, reasons DNA paternity test results are wrong is cross-contamination during collection, which can include touching the swab tip or collecting near someone else.
- Lack of proper storage or shipping puts the swab at risk of bacteria degrading the DNA, which may make the sample unusable when it reaches the laboratory.
- The quality of results is related directly to the laboratory’s accreditation, facilities with CLIA certification implement contamination controls, validated testing protocols, and chain of custody procedures that can’t be reproduced at home or in non-accredited labs.
The answer to the question of can a swab DNA test can be wrong usually comes back to one of these collection or handling issues, not the genetic science.
The Difference Between Home Saliva DNA Tests And Legal Paternity Tests?
A home saliva DNA test and a legal paternity test are the same biological sample type, but NOT the same product. The difference is only in the procedure involved in the sample and not in the swab. The difference between these will decide the scientific validity, the court validity, and the validity for action.
Accuracy, Chain of Custody, and Result Usage
- Salivary DNA testing at home is not supervised, there is no verified identity of the sample collector and no legal chain of custody, and therefore, it is not admissible in court, regardless of the laboratory’s accuracy claims.
- There are restrictions on the use of legal paternity tests, such as the requirement for the collection of samples in the presence of witnesses, identification of the individual, documentation of custody, and testing at recognized laboratories, the steps that ensure result integrity from collection to delivery.
- The choice between saliva test vs blood tests for paternity accuracy is not about the test itself, but rather about how the test is handled in the laboratory. Both have the same level of accuracy when subject to the same professional standards.
Face DNA works with CLIA-certified laboratories to ensure that every case of DNA paternity testing, from routine to complex, is collected, handled, and documented to the highest standards that yield results you can count on yourself and for legal reasons. If you require answers prior to your baby’s birth, Face DNA also provides non-invasive prenatal paternity testing, which does not pose a risk to the pregnancy and provides the same expert-level results using a blood sample from your mother.
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Conclusion
While a saliva DNA test isn’t wrong by itself it can be wrong when the process leading to it is wrong. A reliable result is distinguished from an uncertain one by a string of chain of custody, appropriate collection, and accredited laboratory standards. The security measures of Face DNA’s professional DNA testing services are all built around these. Seek professional assistance, do it right and believe the science for the right answers begin with the right lab behind you.
