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What do the results of genetic tests mean?
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Testing

What do the results of genetic tests mean?

Genetic test results are not always straightforward, requiring careful consideration of medical and family history to interpret their implications for patients and their relatives.

Overview

Interpreting genetic test results can be challenging. It is essential for patients and their families to ask questions before and after testing. Health care providers evaluate results by considering a person’s medical history, family history, and the specific type of genetic test performed.

Understanding Result Types

Positive Test Results

A positive test result indicates that the laboratory found a change in a particular gene, chromosome, or protein. Depending on the test's purpose, this may:

  • Confirm a diagnosis.
  • Identify a person as a carrier of a genetic variant.
  • Identify an increased risk of developing a disease, such as cancer.
  • Suggest a need for further testing.

Because family members share genetic material, a positive result may have implications for blood relatives. Note that a positive result from a predictive or presymptomatic test usually cannot establish the exact risk of developing a disorder or predict the severity of a condition. Rarely, false positive results occur, indicating an increased risk when the person is actually unaffected.

Negative Test Results

A negative test result means the laboratory did not find a change known to affect health or development in the gene, chromosome, or protein tested. This can indicate that a person is not affected by a disorder, is not a carrier, or does not have an increased risk of a specific disease.

However, a negative result does not always rule out a condition, as many tests cannot detect all possible genetic changes. Further or re-testing may be required. Rarely, false negative results occur, where the test indicates a decreased risk when the person is actually affected.

Uninformative Results

In some cases, results are uninformative, indeterminate, inconclusive, or ambiguous. This often happens because everyone has common, natural DNA variations called polymorphisms that do not affect health.

If a test finds a change known as a variant of uncertain significance (VUS or VOUS), it is difficult to determine if it is a natural polymorphism or a disease-causing variant. There may be insufficient or conflicting scientific research to confirm a disease association. In these cases, testing other family members may help clarify the result.

Frequently Asked Questions

VUS classification means the laboratory identified a change in your DNA, but there is not enough scientific evidence to determine whether this change is harmful (pathogenic) or benign. This is common in rapidly evolving genetic fields. A VUS does not confirm a diagnosis or predict disease risk. Your genetic counselor will monitor the scientific literature for new data, and re-evaluation may occur as more cases are studied. :: If I test negative for a specific gene mutation, can I be completely sure I will not develop the associated disease?::A negative result generally means the specific mutation tested for was not found, which is reassuring if that mutation is known to cause the disease in your family. However, it does not guarantee you will not develop the condition, as other unknown genetic variants, environmental factors, or different genes could still contribute to disease risk. It also does not rule out the disease if the test only covers a portion of the gene or if the disease has multiple genetic causes. :: How does a positive genetic test result affect the health risks of my siblings and children?::A positive result for an inherited condition implies that your biological relatives may also carry the same variant. For autosomal dominant conditions, there is a 50% chance that each sibling or child inherited the variant. For autosomal recessive conditions, the implications depend on whether relatives are also carriers. Genetic counseling is recommended for at-risk family members to discuss their specific risks and whether they should undergo predictive testing. :: Can a genetic test result change over time, and when might re-testing be necessary?::Genetic test results for a specific individual's DNA sequence do not change over time; your DNA remains the same. However, the interpretation of a result can change as scientific knowledge evolves, particularly for variants of uncertain significance. Re-testing is rarely needed for the same gene unless new, more sensitive testing methods become available that can detect variants missed by older technologies, or if the initial result was inconclusive due to technical issues.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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