Interpreting Genetic Test Results
While interpreting test results, healthcare professionals consider a personís medical history, family history, and the type of genetic test that was done.
Depending on its intent, the test may:
- Help to confirm a diagnosis
- Determine the carrier status of an individual
- Indicate increased susceptibility to a disease.
a. Testing positive
Testing positive for a genetic disorder means that the individual has a specific gene mutation or chromosomal abnormality for which the test was carried out. Testing positive helps to determine the risk of developing a particular disease, but it does not necessarily mean that the affected individuals will definitely develop the disease during their life time. For example inherited mutations, including those in BRCA1 and BRCA2, contribute to just 5-10% of all breast cancers
A positive test result may also make it necessary for close blood relatives of the person to be screened. It is important to note that a positive result of a presymptomatic genetic test usually cannot establish the exact risk of developing a disorder. Also, health professionals typically cannot use a positive test result to predict the course or severity of a condition.
A negative test result indicates that an individual does not harbor the mutation in the gene that he has been tested for, but this result does not necessarily rule out the disease completely. However testing negative rules out the carrier status and implies that the probability of acquiring the disease is minimal.
Sometimes genetic tests can be ambiguous or inconclusive. In such cases testing other members of the family might help.