Each week in the UK, about 12 seemingly healthy people aged 35 or under are victims of sudden cardiac death, largely due to undiagnosed heart conditions.
If you have a family member who has been diagnosed with an inherited heart condition, or has a family history of premature deaths, doctors will suggest you be tested.
Having angina or a heart attack at a young age can also prompt a test.
Young people should also be checked if they have:
They carry out an electrocardiogram test - also known as an ECG.
This looks at the electrical activity of the heart.
It is painless and involves having small stickers placed on the chest, which are connected to the ECG machine.
A cardiologist checks the results.
Sometimes, an echocardiogram - an ultrasound test that looks at the structure of the heart - is also done.
If someone under 35 has died suddenly, the NHS will offer "cascade testing" to family members to see if they have inherited a faulty gene.
Just being identified helps. People can then be monitored, and encouraged to make any lifestyle changes that could help them.
There are drug treatments available - and people can be fitted with internal cardioverter defibrillators - a matchbox-sized device placed just under the collar bone that gives the heart electric pulses or shocks to get the heart rhythm back to normal.
Other procedures and surgery are also available.
Talk to your GP if you have any concerns.
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About 620,000 people in the UK have a faulty gene that puts them at risk of developing coronary heart disease or sudden death, and most are unaware, heart experts have warned.