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April 2019 | Published by RCPA

Issue #090

Increasing Testing for Familial Hypercholesterolemia

Increasing Testing for Familial Hypercholesterolemia

Familial Hypercholesterolemia (FH) is a common genetic disorder in which the ability to remove low density lipoprotein (LDL) cholesterol from the blood is severely reduced. This results in high levels of LDL cholesterol, which can form plaques known as ‘atheroma’ on the arteries of the cardiovascular system, blocking the flow of blood and increasing the risk of heart attack and stroke. We spoke to Associate Professor David Sullivan to discuss the need for increased testing.

“FH is caused by major variations in the genes, particularly those affecting the LDL receptor. This includes the gene for the LDL receptor itself, the gene for the protein that links to the receptor, and also the gene responsible for the fine-tuning of the receptor, called PCSK9. There are also much rarer causes of FH.

“Just one faulty gene can result in problems with the body removing cholesterol from the blood, causing these levels to increase to up to twice what they should be. This can bring forward the risk of heart attack or stroke by about 20 to 40 years,” said A/Prof Sullivan.

Although untreated (severe) FH can become clinically evident in adulthood, the disorder can be more difficult to identify at a younger age because cholesterol deposits in body tissues take time to develop. In Australia, it is estimated that at least 65,000 people have FH, with the vast majority of them being undiagnosed and/or inadequately treated.[1] Many of those who do receive treatment have not been diagnosed with FH, so the familial implications may not have been recognised.

FH can be diagnosed with a genetic test which will assess whether or not a pathological change in the gene is present. In those patients suspected of having inherited high blood cholesterol, cascade testing can be conducted on family members. Cascade screening is a mechanism for identifying people at risk for a genetic condition by a process of systematic family tracing.

The RCPA has submitted an application to MSAC in relation to genetic testing for FH, which is currently being reviewed. If approved, then it will be possible to refer patients with probable or definite FH for MBS-reimbursed genetic assessment. If a pathological genetic change is detected, cascade screening of close family members will be also be available.

“At the moment, for someone in whom the family genetic pattern is unknown, the cost of this test would be around AU$1,500. Once we identify the change within a family, we can look for that change in other family members through cascade testing,” said A/Prof Sullivan.

In those family members tested, around 50% are likely to have FH as well. Detection early in life will allow those people to make lifestyle changes and also seek drug therapy to lower their blood cholesterol, thereby preventing or reducing the severity of cardiovascular disease. The other 50% of family members will be reassured that they don’t have the inherited condition.

“The associated cost of the test has been very carefully examined. Diagnosing the condition with genetic testing, using that genetic result to test other family members, as well as treating those affected by FH with the routine treatments is a very cost effective strategy, almost to the point of saving money for the healthcare system.

“Once a patient is diagnosed, the condition is actually very treatable. The routine cholesterol lowering treatments, such as statins and intestinal cholesterol absorption inhibitors, all work very well. These are now supported by exciting new biological treatments which are very effective. The first family of these to be approved is called the PCSK9 inhibitors, such as evolocumab and alirocumab,” said A/Prof Sullivan.

 

 

 

 

References:

[1] Bellgard MI, Walker CE, Napier KR, et al. Design of the Familial Hypercholesterolaemia Australasia Network Registry: Creating Opportunities for Greater International Collaboration. J Atheroscler Thromb. 2017;24(10):1075-1084.


 

 

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