What is familial hypercholesterolaemia (FH)?

What is genetic high cholesterol?

Familial hypercholesterolaemia (FH for short) is an inherited condition which can cause extremely high cholesterol levels. It's passed down through families in the genes. 

Without treatment, FH can lead to heart disease at a very young age. But once it's been diagnosed, it can be treated with medicines and a healthy lifestyle.

FH means your cholesterol can become much higher than other people's even if you have a very healthy lifestyle because it affects the way cholesterol is broken down in the body. Dr Sarah Jarvis explains more in this video.


Read about the new pilot screening service to find children with FH


What does 'familial hypercholesterolaemia' mean?

The ‘hyper’ part of hypercholesterolaemia means ‘too high’. The ‘cholesterol’ part simply means cholesterol, a type of blood fat, and ‘aemia’ means ‘in the blood’. So, hypercholesterolaemia means too much cholesterol in the blood, and this can clog up your blood vessels.

The ‘familial’ part of familial hypercholesterolaemia means it runs in families. FH is passed from parent to child in the genes and it’s usually possible to trace FH back through several generations.

Learn about genetic testing for FH

How does FH raise cholesterol?

With FH, there is a fault in one of the genes involved in removing cholesterol from the blood. It happens when you inherit a 'faulty' gene (also known as an 'alteration' or 'mutation') from one of your parents. 

Cholesterol is made by your liver and carried around your body in the blood. It’s then taken into your cells to be used or stored and any excess can be carried back to your liver and broken down.

FH can cause problems with these natural processes. It means LDL cholesterol (sometimes known as bad cholesterol) can’t be taken out of your blood quickly or easily, so it can build up.

Our liver cells and many other cells in our bodies have small structures on them called LDL receptors, which have an important job in keeping blood cholesterol down.

LDL receptors attach to LDL cholesterol as it passes by in the blood and carry the cholesterol into the cell. The cholesterol is used or stored for later, or broken down by liver cells. The LDL receptor then returns to the surface of the cell, ready to bind to more cholesterol in the blood.

With FH, the liver cells can’t take LDL cholesterol out of your blood, and this is down to faults or mutations in a few specific genes.

Which genes are involved in FH?

There are three main genes, or sets of genes, which can be involved in FH.

1. LDL receptor genes

Most people with FH have a fault in one of these genes. It means you don’t have enough LDL receptors, so cholesterol builds up in the blood.

2. APOB gene (apolipoprotein B)

Only two or three out of every 100 people with FH have a fault with this gene. It means LDL cholesterol can’t bind well to LDL receptors. LDL is taken out of the blood too slowly and blood cholesterol stays high.

3. PCSK9 gene

Only a few people have this type of FH. A fault with this gene means that LDL receptors are broken down in the liver so they can’t take cholesterol out of your blood.

Other genetic conditions

There are other genetic conditions which can cause high cholesterol. For example, polygenic hypercholesterolaemia, where instead of one gene causing the high cholesterol, small problems with many genes all add up.

There is also a rare type of FH where you inherit two faulty genes rather than one which raises cholesterol even further. This is known as Homozygous FH or (HoFH).

A note on prescriptions for treating FH

HEART UK would like to see an exemption from prescription charges for people with FH, in a similar way that other medical conditions have. This may be unlikely, but we will keep the conversation going. In the meantime, if you have FH, consider asking your GP to prescribe three months worth of medication for one prescription, once you are on a stable dose with well controlled LDL cholesterol levels. There may also be pre-payment options available.

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