DNA Test Accuracy: How Reliable Are They Really?

How Accurate Are DNA Tests

Globally, millions of people are testing their DNA, but how accurate are DNA tests? Accuracy depends on so many factors - the type of test taken, where it's taken, who takes it, the labs conducting the test, and our list could go on. 

When you choose a reliable, accredited company like AttoLife to assist you with your DNA testing, you ensure reliable and accurate results.

DNA test accuracy is essential. Understanding the entire DNA testing process and what might affect the result will help you get the most accurate result.

Read on to find out more.

Factors Influencing the Accuracy of DNA Tests

1. Quality of the DNA Sample

The quality of the DNA sample massively influences the precision of the results. If the sample is contaminated in any way or of poor quality, the results will most likely be unreliable. 

Some common problems consist of:

• Insufficient DNA Quantity: Failing to submit the proper amount of DNA will result in inadequate and unreliable DNA analysis. This can happen more commonly with at-home DNA tests. If you're using an accredited and trusted DNA collection service with professionals who collect the sample for you, it's highly unlikely that insufficient DNA sample collection will ever occur.

• Contamination: Foreign material, like food and drink, collected during swabbing can hinder the laboratory process and reduce the concentration of DNA recovered from the swab. Furthermore, the presence of other people's DNA will completely taint the sample. People don't necessarily do this on purpose, but, for example, if someone rests the DNA swab on the side after conducting the sample collection instead of into the correct packaging, it's instantly contaminated. Again, this is common with people using at-home DNA test kits rather than professional sample collection officers.

It is essential to follow instructions from the collection process to reduce contamination risk. Each testing kit will include specific instructions, most likely including pictures for guidance and, more recently, QR codes leading to a video link to follow someone step-by-step.

2. Methodology and Technology Used

The accuracy of results in DNA testing correlates to the techniques used. Techniques like the Polymerase Chain Reaction (PCR) and the advancement of DNA fingerprinting methodologies with Short Tandem Repeat (STR) analysis are known for their high levels of discriminatory power. These techniques are capable of amplifying and analysing specified regions of DNA where reliable results are guaranteed.

3. Laboratory Standards and Accreditation

The most important thing when it comes to the laboratory performing the test is competency and transparency. Accredited laboratories apply strict control of quality measures, therefore reducing errors. Testing laboratories that adhere to international standards such as ISO 17025(2017) with certified accreditation from one of several renowned institutions, like  UKAS, possess international standards of testing and calibration which proves the lab's credibility.

At Attolife, we are UKAS-accredited laboratory (number 2699) to work within the ISO 17025(2017) requirements and have Ministry of Justice approval to conduct court-directed parentage tests under section 20 of the Family Law Reform Act 1969. 4. Human Error

Human error is more likely to be the cause of false or rejected DNA samples. Human error can include:

• Sample Collection: An error in labelling, storing, or transporting a specimen can lead to cross-contamination.

• Data Interpretation: An inadequate analysis or incorrect entry can lead to omissions.

To minimise the risk of human error, trustworthy companies have strict policies and follow stringent measures such as  cross-checking, strict training regimes, internal and external auditing programmes and document verification throughout the testing process.

How Accurate Are Paternity Tests?

Paternity tests are one of the most in-demand types of DNA tests. The accuracy of these tests depends on multiple factors:

1. Testing Method

Paternity tests check for multiple genetic links. The higher the number of markers tested, the greater the degree of confidence. Tests using claim accuracies of 99.99% or slightly higher, making a strong claim to paternity. Advanced tests are typically performed by reliable companies with professionals who take the sample for you. It is also noted that the more genetic markers are analysed, the more reliable the test becomes.

2. Inclusion of the Mother's DNA

Bringing in the mother's DNA sample could improve accuracy. Deducting the genetic markers that the child inherited from their mother helps isolate the child's alleged father's genetic contribution. With the mother's DNA included chances of exclusion and erroneous inclusion are minimised. This route is not always viable if the mother is unable or unwilling  to provide a DNA sample. As standard, using advanced tests to confirm paternity relationships using only the father and child's DNA sample is sufficient.

3. Legal vs. Non-Legal Testing

For a paternity test to be legally accepted, there has to be a strict chain of custody throughout the whole testing process, from the initial sample collection to the release of the final report. .

This includes sample collection performed by a trained sample collection officer and accurate labelling,documentation and a clear record kept throughout the whole process. Non-legal (or "peace of mind") tests often adhere to many  of these strict protocols. However, there can be no clear chain of custody when using home testing kits as it is impossible to independently confirm the samples were collected from the correct donors. Hence, there is no way to prove that the test results reflect the intended donors in a court of law.

Can DNA Tests Be Wrong?

Yes, if anything we've discussed so far happens, a DNA test could throw out a false result. However, there are other factors aside from human error and the type of test that can create an inaccurate result. These include:

1. Chimerism

Chimerism is the phenomenon where a person has two different DNA sets. Chimerism occurs when an individual has two distinct sets of DNA, which can happen from the absorption of a twin. Such rare cases may lead to erroneous results from a DNA test due to different body tissues having different genetic constitutions.

2. Bone Marrow Transplants

Bone marrow transplant recipients contain the DNA of their blood cell donor. If the DNA in question derives from bloodstained tissue and blood-forming tissues associated with the person, the results could undermine the integrity of the DNA sample.

3. Extended Relationship Testing

As we explored in our recent webinar on DNA testing, the more distant the relationship between people (such as a grandparent, or aunt or uncle), the more genetic markers are needed to establish that people are related to each other with the highest degree of certainty. While this doesn’t make the test “wrong” per se, if the test is being used for legal purposes, you need to be able to prove beyond doubt that the relationship is there, especially in custody or inheritance cases.

Can You Trust DNA Results?

Considering everything we've discussed, it is quite reasonable to ask if the results from a DNA test can be trusted. With some precautions in place, you can achieve a degree of confidence in the results:

1. Choose Reputable Testing Companies

Reputable firms have their laboratories accredited by recognised bodies and will always follow predefined quality control steps. For example, Attolife guarantees accurate and transparent testing processes through compliance to international standards and years of experience delivering accurate results, both in legal settings and for personal reasons.

2. Follow Collection Instructions Carefully

Adhering to the provided checklist for sample collection is very important, particularly because it is often the only chance to collect a sample. Seemingly intricate techniques that must be followed greatly mitigate the possibility of contamination and insufficient samples material. For example, most tests will ask you to rigorously swab each cheek in a circular motion 10 times for accurate sample collection, which ensures that sufficient cellular material is transferred to the swab.

3. Understand the Test's Scope and Limitations

Every test has a different margin of accuracy. For example, estimates provided by paternity tests can be more reliable than estimates for second cousins confirmation tests. At a minimum, having a basic understanding of what a test entails goes a long way.

The analysis of DNA has greatly transformed the dynamics of relationships and has become a conclusive factor for court cases like child custody cases. Although these tests are, on the surface, highly accurate, it is essential to keep in mind factors that stand to undermine your reliability.

If you need a professional DNA testing service or would like advice about the process, contact Attolife today.

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