Genetic Testing

Sudden Cardiac Arrest

Our genes are like an instruction manual which our body reads to know how to work. Sometimes, if there is a change in the instruction manual (a spelling mistake), this changes the message the body receives and can lead to disease. Genetic testing tries to identify these changes and can help identify the cause of a sudden cardiac arrest

Genetic testing for a person who has had a sudden cardiac arrest is usually organised through a genetics service or a genetic heart disease clinic but may also be organised by a cardiologist.

We usually begin genetic testing in the person who has had the sudden cardiac arrest.

Genetic heart disease clinics

From genetic testing, you will get one of three results:

Nothing Identified

No changes were identified in the genes tested. If nothing is found on genetic testing no further genetic testing is likely to be helpful for family members in the short term. Family members are recommended to have repeat heart checks with a doctor specialising in heart health (cardiologist) every few years.

If nothing is found on one genetic test, it may be helpful to revisit and repeat genetic testing at a later date. Our knowledge about genetics is increasing everyday, and so are the technologies used to test genes. New discoveries in the future are expected to continue to improve genetic testing and identify new causes of cardiac arrest.

A definitive cause found

A DNA change is identified that is believed to cause one of the genetic heart diseases that can lead to sudden cardiac arrest.

The chance of finding the gene change depends on the condition. For example, with hypertrophic cardiomyopathy (HCM), the chance of finding a gene fault causing disease is up to 50%. If heart tests have not been able to find any cause for a cardiac arrest, the chance of a genetic test finding a cause may be lower, at around 10%.

If a definite cause is found through genetic testing, first degree relatives (siblings, children, parents) can have a genetic test too. This is to see if they carry the same gene change and are at risk of developing the same heart condition. Family members might like to talk to a genetic counselor about genetic testing. Genetic counselors can guide and support people who are seeking more information about inherited conditions.

An uncertain result

Also called a “Variant of Uncertain Significance (VUS)

This means a change in the DNA has been identified, however it is uncertain if the change causes a heart problem or if the change is just normal genetic difference in the population which has no affect on the heart. All people are different and unique. All people have normal variation in their genes. Current knowledge of genes and DNA changes is not complete. We don’t know everything there is to know about genes. That’s why a genetic test result sometimes has an uncertain result.

In the future more evidence may help classify the change. Over time, we hope that we will be able to determine with more certainty, which gene changes cause heart disease, and which do not.

How can I find out if genetic testing will help my family?

How do I organise genetic testing?

Genetic testing needs to be ordered by a doctor. Most genetic tests are organised by doctors in local genetics services or specialist genetic heart disease clinics. Genetic services are located at most major hospitals with outreach clinics available to those in rural and regional areas.

You will need to ask your GP for a referral to your local Genetics Service. To find your local service please visit the Centre for Genetics Education Website. https://www.genetics.edu.au/SitePages/Genetic-services-listing.aspx

Genetic Heart Disease Clinics are multidisciplinary clinics which specialise in clinical care and cardiac genetic testing. They are located in most capital cities and have strong connections with genetics services. A list of genetic heart disease clinics can be found here

Further facts sheets about cardiac conditions as well as genetics can be found here: https://www.nswhearts.org.au/factsheets/

Genetic counsellors and psychology support can help navigate the emotional impact of genetic testing

Although finding a genetic answer as to why a sudden cardiac arrest occurred can be beneficial, this can also come with struggles. Such as struggles of guilt of having passed on the genetic change or now added worry for the health of other family members.
People also find it difficult when no genetic cause of the cardiac arrest is identified. They sometimes struggle with the uncertainty of not knowing the cause.
We recommend speaking to a genetic counsellor to discuss the psychological impact of genetic testing results.