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Genetic causes of
sudden cardiac death

What are genetic causes of sudden cardiac death?

Sudden cardiac death can be caused by genetic diseases that affect the structure of the heart, or the way the heart’s rhythm works (electrical currents). 

Cardiomyopathies are heart conditions that can change the structure of the heart and will often be picked up at postmortem. Diseases that change the rhythm of the heart will not show up at postmortem as the heart looks normal.


Sometimes postmortem findings are not clear. Genetic testing can provide more information to help find the answer (see below).

The heart muscle becomes thicker

Hypertrophic cardiomyopathy (HCM)

The heart enlarges and becomes big and baggy, so it does not pump properly

Dilated cardiomyopathy


Causes rhythm problems in the heart and can impact how well the heart works


No cause of death is identified at postmortem and a genetic heart rhythm problem is suspected

Unexplained death

A rhythm problem of the heart, where the heart takes too long to relax between beats

Long QT Syndrome

A rhythm problem of the heart that causes a dangerous, irregular heartbeat

Brugada Syndrome


 A rhythm problem of the heart which can be made worse by exercise or an adrenaline hit e.g. riding a rollercoaster

Catecholaminergic polymorphic ventricular tachycardia (CPVT)

These diseases affect the parts of your body that connect other parts together. The diseases can cause a tear in the body’s main blood vessel, the aorta

Marfan syndrome

For more information

Coronary artery disease (CAD) or familial hypercholesterolaemia (FH)

Coronary artery disease is often caused by lifestyle factors such as diet and exercise habits. Some people develop coronary artery disease at a young age because of high cholesterol caused by a genetic condition called familial hypercholesterolaemia (FH) Find out more about FH at the FH Foundation website.

Sudden Unexpected Death in Epilepsy (SUDEP)

SUDEP is where someone with a diagnosis of epilepsy, dies suddenly and no cause of death is identified. 

Do my family need screening (heart checks)?

If a genetic or suspected genetic cause of death is identified at postmortem, clinical guidelines recommended first degree relatives (children, siblings, parents) have clinical screening (heart checks) with a heart specialist (cardiologist).

Tests should include a clinical examination which may include a blood pressure and pulse check, an electrocardiogram (ECG), echocardiogram (ultrasound of the heart) and an exercise treadmill test.

Your general practitioner (GP) can organise a referral to a cardiologist who completes these tests.

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