Generation I of V · The basics
What genetic testing is
Genetic testing is a laboratory look at your genes for changes in your DNA: changes that can cause health problems, or that raise the chance of developing some diseases. healthdirect says it can help diagnose some genetic conditions, and that the test is only the first part, because what matters most is understanding what the result means.
General information, not medical advice. Call Triple Zero (000) in an emergency, or go to the emergency department of your nearest hospital. The official consumer page to check is healthdirect’s page on genetic testing.
Genes and DNA
Genes, DNA and mutations
healthdirect says you have more than 20,000 genes, and that they carry information that can set your physical traits, your characteristics and your general health.
A few words come up again and again on official pages. Each is given here as the page that uses it defines it.
- Mutation
- A random change in your DNA, in healthdirect’s words.
- Genetics
- The study of how genes work and pass information from parents to their children. The federal health department says it can help in understanding the risk of a genetic disease being inherited.
- Genomics
- The mapping and study of genomes: an organism’s full set of genetic instructions. It covers human and other genomes, and how they interact with the environment.
- Carrier screening
- Tests to find out whether you carry a gene that may cause a genetic problem if it is passed on to your children, as healthdirect puts it.
The test
What a test looks for
In a genetic test, a laboratory checks your genes for mutations. Finding one is not the same as finding an illness: healthdirect says a positive result for a mutation does not always lead to the disease that gene is linked with. Results and your family goes further into what a result can mean.
The federal health department describes three ways genomics can help doctors:
- to identify and diagnose genetic disorders and rare diseases
- to develop prevention strategies
- to tailor a patient’s treatment.
Those are the department’s words for what the field offers doctors in general. They are not a promise about any one test or any one condition.
Reasons for testing
When a test might be considered
healthdirect’s full list, under the question “When might I consider genetic testing?”, says you might consider it if:
- you have a newborn baby, as some rare genetic conditions can be detected with a simple blood test
- you are early in pregnancy, when the chance your baby has a genetic condition such as Down syndrome can be checked with non-invasive prenatal testing
- you are planning a pregnancy, when carrier screening can test for many genetic conditions, including cystic fibrosis, fragile X syndrome and spinal muscular atrophy
- someone in your family has a genetic condition and you are worried that you or your children will develop it
- you have been diagnosed with cancer
- a child of yours has growth, development or health problems that affect them severely
- you and your partner are related by blood.
The sample
How a test is taken
healthdirect says genetic tests are usually carried out at special laboratories, and that most are blood tests. For the reproductive carrier tests covered by newer Medicare rebates, the Health Minister’s release says a blood, saliva or cheek swab sample can be used.
On its page about nutrigenetic tests, which look at how genes, diet and health relate, the Therapeutic Goods Administration (TGA) explains that, depending on what the manufacturer claims, some of them are therapeutic goods, regulated as in-vitro diagnostic (IVD) medical devices, and that IVDs are sorted into four classes by the risk they pose to the public or to the person tested. The TGA also says genetic self-tests, meant to find or predict a disease at home, may not be supplied in Australia.
Ordering
Ordering a test
healthdirect says it is best to see your doctor or a genetic counsellor if you are thinking about a test. It also notes that tests can be ordered online without seeing a doctor, and passes on a warning to be careful about this.
Some of the companies selling tests online are based overseas, healthdirect says, and they may take less care with privacy than Australian companies, so your private information could end up with others. This site stays with tests ordered through a doctor; Medicare and genetic tests explains when Medicare pays towards one.
Trade-offs
Benefits and risks in healthdirect’s words
The benefit
healthdirect describes the main benefit as knowledge: once you have had a test, you can get advice about what the result means.
The risks
healthdirect says results can shape your health choices and some decisions your family might make, that there are privacy risks, and that results can be hard to understand.
healthdirect adds that for understanding what a result means, you should talk to a doctor or a genetic counsellor.
That is why Genetic counselling sits in the middle of this chart.