HEALTH

How genetic testing can help you make important health choices

29 February, 2024 . 0

Are you concerned your genes put you in the path of a serious disease? Genetic testing may help provide the answer, but it’s not always a simple decision.

When Angelina Jolie opened up about undergoing a preventative double mastectomy in 2013, she created global headlines – and thrust genetic testing into the spotlight.

The Hollywood star had been tested for the BRCA1 gene, which increases the risk of breast cancer, and took the drastic step of surgery after discovering she was a carrier of the “faulty” gene.

Huge strides in the field of genetic testing in the past decade have meant more people are finding out their risk of a range of ills, the Centre for Genetics Education (GCE) says.

But the decision to get genetic tests done should not be made lightly, as it can have emotional and psychological consequences and ramifications for family members.

What is genetic testing?

The CGE describes genetic testing as “studying a person’s DNA or the message that the DNA code is sending to the cells of the body”.

The many different tests available are commonly offered to people with a family history or symptoms of a genetic condition, when a family member has been diagnosed, and for screening in pregnancy.

Associate Professor Kristine Barlow-Stewart, a former director of the CGE, says the area is increasingly being referred to as genomics and has been subject to huge advances in recent years.

“When I first started in this field, 30 to 40 years ago, we could only test a single gene out of the 20,000 genes that we have,” Assoc Prof Barlow-Stewart, who is an honorary academic at the University of Sydney, says.

“Now our technology allows us to screen all of the genes at once.”

She says costs can vary from hundreds to thousands of dollars, but genetic testing is covered by the public hospital system for patients referred by a specialist.

Screening for high-risk variants in selected genes is covered by Medicare for those who meet certain criteria, and rebates also apply to eligible women and their reproductive partners who are pregnant or planning a baby.

What diseases can be detected through genetic testing?

The risk of developing heart disease, the leading cause of death in Australia, is one of the most common reasons people undertake genetic testing, Assoc Prof Barlow-Stewart says.

A predisposition to a range of genetic conditions can also be uncovered including:

Breast, bowel, ovarian and prostate cancers
Melanoma
Diabetes
High cholesterol
Blood conditions
Mental illness
Neurological conditions such as early-onset Alzheimer’s disease
Chromosomal conditions, including Down syndrome and Turner syndrome

“Genetic testing doesn’t give people certainty,” Assoc Prof Barlow-Stewart points out.

“It might tell them that they have an increased chance of a condition, but there (are) lots of steps that have to be taken at the DNA level before the breast or ovarian cancer, for example, actually start to occur.”

How are genetic tests performed?

A sample of body tissue is taken from a patient, which may include blood, saliva, skin or roots of the hair, from which the DNA is extracted, Assoc Prof Barlow-Stewart explains.

“We then break it up into little bits and look at each individual gene, and compare what information is in that gene to what we would expect to be there,” she says.

“If it has changed, we then look at that particular change in the information in the gene, and see whether that change could cause a problem with how the gene works – we call it a ‘gene fault’.

“The tests are very accurate if we find something.”

How long does genetic testing take?

In the past, Assoc Prof Barlow-Stewart recalls, it could take years to get a result.

But now, it can take just weeks or even days if the case is urgent.

Can you do genetic testing during pregnancy?

A number of tests can be done in the early stages of pregnancy to screen for birth defects such as Down syndrome.

The Royal Women’s Hospital explains that the decision is personal, and genetic tests can’t be carried out after 19 weeks.

What do you need to consider before genetic testing?

It’s important to consider what the answers will mean for you and your family, Assoc Prof Barlow-Stewart says, and she suggests talking to a GP or genetic counsellor at the outset.

“It’s different to every other medical test because the results are not only about you, they’re about your family,” Assoc Prof Barlow-Stewart says.

“There can be an impact on family relationships; some people don’t want to know their health future and others do.”

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Written by Elissa Doherty.