Understanding Genetic Testing
Genetic testing is a fascinating and rapidly evolving field of medicine that offers insights into our DNA, the blueprint of life. It involves examining your DNA to identify changes or mutations that could indicate a predisposition to certain health conditions. But what does it entail, how much does it cost, what are the risks and benefits, and just how accurate is it? Let’s dive in.
What is Genetic Testing?
Genetic testing involves analysing your DNA—the chemical database that carries instructions for your body’s functions—to find changes (mutations) in your genes that may cause illness or disease. It can confirm or rule out a suspected genetic condition or help determine a person’s chance of developing or passing on a genetic disorder.
How is Genetic Testing Done?
There are many ways to collect and test DNA. Almost every cell in our body contains DNA, although the most common sample types are blood or saliva as these give good amounts of DNA.
Laboratory scientists can take a sample from a person and process it to extract the DNA.
Depending on the characteristics of the gene being tested, or the kind of genetic testing that has been requested (such as single gene testing, or testing the whole genome), certain machines and procedures will be used. These are designed to accurately determine the sequence of DNA in a gene. In other words, genetic testing is trying to figure out the “spelling” of a gene in order to find any areas that may have a “mistake”, or mutation. These mutations could be a single “letter” out of place, or could be large areas of DNA that have been deleted, added or moved to a new place in the genome.
Computers are used to check the DNA sequence and pick out changes that could be important. A specialist scientist can look through the data that is produced and check if any of the changes that have been found are likely to cause disease. This information is then used to make a report, or result, which can be sent to the health professional who requested genetic testing.
The Cost of Genetic Testing
The cost of genetic testing can vary widely, from under $100 to more than $2,000, depending on the complexity and nature of the test. It may increase if multiple family members need to be tested or if multiple tests are necessary to obtain a meaningful result.
In Aotearoa New Zealand, people who are eligible can access genetic testing fully funded by the NZ government. The public Genetic Health Service has eligibility criteria in place that need to be met in order to have access to this service.
At Genetic Insight, there are costs associated with accessing the support of genetic counselling as well as the cost of the testing. These costs vary based on several factors, but a good estimate to expect to spend is somewhere around $1000 for everything.
Insurance companies may fund some genetic testing, but not all. It’s a good idea to check with your insurance provider before undergoing genetic testing.
Risks Involved with Genetic Testing
While the physical risks associated with genetic testing are generally small, especially for tests that require only a blood sample or cheek swab, some kinds of tests can hold risk. Prenatal testing (testing done on a pregnancy), such as amniocentesis or chorionic villus sampling, carries a small risk of pregnancy loss (miscarriage), for example.
There are other risks to consider to, such as the emotional, social, or financial impact of genetic testing. A genetic result may impact access to insurance cover, with insurance companies refusing cover for cancer-related services in people with a proven hereditary cancer risk, for example. Receiving a genetic result can lead to feelings of uncertainty, anxiety, guilt, or tension within families.
Genetic testing done through laboratories that are not accredited, or that perform limited genetic testing (such as ancestry testing and simple health screens) can be risky and is not recommended for diagnosing genetic conditions. There is an increased risk of incorrect or misleading information being returned from this kind of testing. There can also be risks regarding storage of DNA samples and data as well as the risk of uncovering unexpected family secrets, such as adoption.
Genetic testing is safest when done with the support of a genetic counsellor or genetic doctor. It is their job to make sure that the best tests are being ordered to suit your health needs, and that the laboratory doing the testing is appropriately accredited. Other health professionals can order certain genetic tests, but they are not always as familiar as they should be with the process and possible risks for a patient or their family. Support from a genetic service is always encouraged, wherever possible.
Benefits of Genetic Testing
Despite the risks, the benefits of genetic testing are significant. A positive result can guide individuals toward available prevention, monitoring, and treatment options. It can also help with family planning decisions, as some test results can reveal the likelihood of passing on a disease to children. Newborn screening can identify genetic disorders early in life, allowing treatment to start as soon as possible which can reduce the impact of some genetic disorders.
Information gained from genetic testing can provide closure for people who have been uncertain about a diagnosis or were seeking an explanation for their illness. Genetic results can improve perceived personal control and empower people to make informed decisions about their health.
Accuracy of Genetic Testing
The accuracy of genetic tests depends on the type of test and the specific condition being tested for. Generally, tests for monogenic traits (conditions caused by mutations in a single gene) are more reliable. Analytical validity and clinical validity are two main measures of accuracy, determining whether a test can accurately detect a mutation and if that mutation is linked to a specific disease.
Before undergoing any genetic testing it is always important to have a good understanding of the laboratory carrying out the testing. Are they accredited to do this type of testing? What sort of genetic changes are they able to pick up? Is there anything they might miss in testing? Arranging genetic testing through a registered genetic counsellor will ensure that the testing being done is as accurate as possible.
Genetic testing is a powerful tool that can provide valuable information about your health and the health of your family. However, it’s important to approach it with a clear understanding of the costs, risks, benefits, and accuracy. If you’re considering genetic testing, consult with a healthcare professional or a genetic counsellor to make an informed decision.
Looking for more information?
Here are some websites that may be useful.
Human Genetics Society of Australasia Home (hgsa.org.au)
Genetic Health Service NZ Home | Genetic Health Service NZ
Centre for Genetics Education Welcome — Centre for Genetics Education – Welcome – Centre for Genetics Education