UK gene tests for tens of thousands of young people
Posted Nov 21 2008 4:29pm
Under proposals to be announced next week by the National Institute for Health and Clinical Excellence (NICE), nationwide testing for tens of thousands of young people for a genetic defect that can kill them in their twenties.
The tests will include children as young as ten, and focuses on those whose mother and fathers were known to have high cholesterol levels. Up to 120,000 people in Britain carry genes that cause high cholesterol levels. The genes Carriers have a much higher risk of developing heart disease at a younger age than other people, and dying from it before they are aware of the risk.
The tests will aim to detect familial hypercholesterolaemia (FH), which is the most common genetic disorder among young people of European descent.
At this point, less than a fifth of the 120,000 carriers of the FH genes know that they have the condition. According to Alan Rees, chairman of the charity Heart UK, this represents a “systematic failure”, and is “a disgrace”.
Many people with FH die suddenly of heart attacks that could easily have been prevented with statins, a treatment that lowers a carriers cholesterol levels.
The NICE guidance is expected to recommend “cascade screening”, in which close relatives of every identified FH sufferer are screened for the three genes that cause half of all cases.
NICE says cascade screening would be straightforward to introduce in Britain, would cost relatively little, and could save thousands of lives. The simple test, costing £200, can establish if someone is a carrier of any of these genes.
Child carriers of the gene begin to suffer from furred-up arteries as young as 8. By the time they reach their twenties the arteries can be as damaged as that of a 50-yer-old, yet sufferers have no obvious symptoms and most are unaware of the risks that they run. Statins can lower the heart risk to normal levels.
“Statins will halve levels of the bad form of cholesterol,” said Dermot Neely, a consultant at the Royal Victoria Infirmary in Newcastle upon Tyne. “And they are as cheap as chips - cheaper, actually. The problem is getting people on to treatment before they have a heart attack. Heart attacks that occur at a young age are often fatal, so we need to identify FH as early as possible. We may need to start treating in childhood.”
The hardest part is to identify the cases. A parent has a 50-50 chance of passing on the gene to a child, so once an “index case” is identified; close relations will be asked whether they want to be tested.
The new guidance will recommend that the children of those affected by FH should take the test by the age of 10. Those found to be positive will be advised about leading a healthy life, and counselled especially strongly not to start smoking. The first option for drug treatment is simvastatin, which is cheap, but for more severe cases more potent statins may be needed.
In extreme cases, a form of dialysis in which cholesterol is removed from the bloodstream may be considered.