A saliva DNA test involves collecting a sample of your spit for laboratory analysis. While generally reliable for purposes like ancestry tracing or identifying genetic predispositions, these tests can yield inaccurate or misleading results. Understanding potential issues is important for correct interpretation.
Understanding Saliva DNA Testing
A saliva DNA test begins with collecting a sample, often using a home kit. These cells from your cheek carry your DNA. The sample is then sent to a laboratory for processing.
In the laboratory, DNA is first extracted from the collected cells. After extraction, DNA undergoes amplification, creating many copies of specific regions. These amplified fragments are then analyzed using various technologies, such as genotyping or sequencing, to read the genetic code. Finally, raw genetic data is interpreted using computational tools and reference databases to generate results.
Common Causes of Inaccurate Results
Errors can occur at several stages of saliva DNA testing, potentially leading to inaccurate results. Pre-analytical errors occur before the sample reaches the laboratory. These include insufficient saliva, contamination from foreign DNA (e.g., food, drinks, or another person’s DNA), or improper storage/shipping conditions like extreme temperatures, which can degrade DNA.
Problems can also emerge during the analytical phase in the laboratory. Risks include cross-contamination between samples during processing, equipment malfunctions (e.g., with extraction or sequencing instruments), human error during steps like pipetting or handling reagents, or using expired/improperly stored reagents.
Even after laboratory analysis, errors can occur during the post-analytical phase, involving data interpretation and reporting. This includes issues with bioinformatics algorithms or reference databases. Misinterpreting complex genetic variations can lead to false positives (indicating a marker not present) or false negatives (failing to detect a marker). These issues can also lead to inconclusive results.
Key Factors Affecting Test Reliability
The reliability of a saliva DNA test is influenced by several factors. The quality and accreditation of the laboratory performing the test are paramount. Laboratories that adhere to recognized standards, such as those set by the Clinical Laboratory Improvement Amendments (CLIA) in the United States, demonstrate a commitment to rigorous quality control and proficiency testing. Such accreditations indicate that the lab meets high standards for analytical validity and reliability.
The specific type of DNA test being performed also plays a role in its inherent accuracy. Some genetic questions are more straightforward to answer accurately than others. For example, ancestry tests rely on broad genetic markers, while tests for specific health markers might require more precise and sensitive analysis. The complexity of the genetic information being sought can influence the potential for ambiguity or error in the results.
Furthermore, the user’s adherence to the provided instructions is a critical factor directly impacting the quality of the collected sample. Following pre-test instructions, such as refraining from eating, drinking, or smoking for a specified period before collection, helps ensure the sample is not contaminated. Proper sealing and timely shipping of the sample are also important to preserve DNA integrity. The diligence of the individual collecting their sample directly affects the quality of the input material for the laboratory.
Steps to Maximize Accuracy
To help ensure the most accurate results from a saliva DNA test, start by choosing a reputable and accredited laboratory. Look for certifications such as CLIA accreditation or other equivalent international standards, as these indicate adherence to strict quality control measures. Reading reviews and researching the company’s track record can also provide insight into their reliability.
Once you have a kit, follow the instructions meticulously. Each kit comes with specific guidelines for sample collection, including details on when to collect the sample and what to avoid beforehand. Adhering to these instructions precisely helps ensure a high-quality sample that is suitable for analysis. This includes ensuring sample purity by avoiding any contamination before and during the collection process.
Properly registering your kit with the testing company is also important to prevent any mix-ups or delays in processing. If the results you receive are highly unexpected or contradict information you already know, considering a retest might be a prudent step. You might even consider using a different accredited lab for the retest to provide an independent verification. For any health-related DNA results, it is always recommended to consult with a healthcare provider or a genetic counselor. These professionals can help interpret complex genetic information and provide personalized guidance.