Genetic testing: what, why and where
We have the ability to test for genes which we may carry and pass on to children, or to test our DNA to see if we are likely to develop certain conditions. We can even test which medications are likely to be safer or more effective for our particular genetic makeup.
There are several different types of genetic testing. Each has a different role to play in managing our health.
The Australian National Health Genomics Policy Framework 2018–2021, which aims to integrate genomics into national healthcare, strongly supports that genetic testing
should be done in consultation with your general practitioner or specialist genetic clinic, so talk to us if you are thinking about any genetic testing.
Preconception genetic carrier screening
Healthy people planning a pregnancy can get tested to see if they carry a recessive gene which could result in certain serious diseases in their children. This ‘preconception genetic carrier screening’ can be done through your GP for relatively common genetic diseases such as Cystic Fibrosis (CF), Spinal Muscular Atrophy (SMA) and Fragile X Syndrome (FXS). It is widely available on a simple blood or saliva test for around $350.
A common misconception is that screening is not necessary if a couple have no known family history of a genetic disorder. Almost 90% of carriers of CF, SMA and FXS have no known family history of the condition, which is why it is now recommended that all people planning a pregnancy should consider screening for these diseases.
In most cases, ‘sequential screening’ is performed. This means the maternal DNA is tested first. Only if the maternal test shows a positive carrier status for one or more genetic condition is the paternal DNA tested. So, in many cases, only one test will need to be performed.
If it is found that both genetic parents carry a recessive gene, there is a one-in-four chance that a child will affected by the condition. In these situations, prospective parents can receive information on the condition and can take steps to avoid transmitting the disease if they choose to.
Genetic testing
The way we look at health is always changing. There is growing evidence to show that many health conditions, like heart disease, certain cancers and dementia, can be detected in our DNA many years before they arise. This has led to a huge interest in genetic testing. For example, when there is a family history of cardiac arrest or unexplained sudden death in young people, it is now possible to screen for genes which are associated with electrical abnormalities of the heart which can lead to sudden death. Detection of one of these genes means preventative steps, such as implanting a tiny defibrillator next to the healthy heart, can be lifesaving!
Many companies now offer screening for a vast array of genetic conditions direct to consumers through testing kits available online. It is important to understand what these tests can and can’t tell you and how the results can impact on you, now and into the future. For instance, there are potential life-insurance implications of obtaining genetic test results.
Pharmacogenetic testing
People respond to medications differently because of variations in the genes that determine how the body processes and reacts to the medication. It is now possible to test if you carry specific genes in your cells that can make certain medications ineffective or even toxic for you. Medications which we can test the genes for at this time include some antidepressants, blood thinners and certain cancer treatments.
Using genetic testing in medicine is a new frontier, and we are all just getting to grips with how best to use this technology. The doctors at LGP are very happy to discuss any questions you have about genetic testing.
