High cholesterol isn’t always caused by lifestyle, it can also be caused by your genes. In fact, your genes can affect your blood fats in many different ways.
You might hear genetic conditions called inherited conditions. This simply means they’re passed down in families.
A number of genetic conditions can affect your blood fats. These include more common conditions such as polygenic hypercholesterolaemia and rarer conditions such as homozygous FH.
How do your genes raise cholesterol?
Your genes play different roles in how fats are managed in the body, including how they are:
- absorbed from the food you eat, from the gut into the blood stream
- carried around your body in the blood
- packaged up by your liver
- taken into your cells to be used for jobs such as making hormones
- broken down and removed from your body by your liver.
A fault in a gene can mean that blood fats aren’t built up or broken down as they should be, so levels in the blood can rise.
Many different genes are involved in managing your blood fats. Sometimes just one faulty gene can be enough to raise your cholesterol, but high cholesterol can also be caused by the small effects of many faulty genes all added together.
It’s not the gene itself that causes a disease, but a fault in a gene. You might hear these faults called mutations, alterations or changes.
All of our cells have two copies of every gene – one from mum and one from dad.
With some genetic conditions you only need to inherit one faulty copy of the gene involved, and with others you need to inherit two – one from each parent. This means a condition can be inherited in different ways, for example:
- Dominant or "autosomally dominant". This is where you only need to inherit one faulty copy of the gene to have the disease. Only one parent needs to have a faulty copy, and they will have the disease themselves. If one parent has the disease, there’s a 50% chance it will be passed on.
- Recessive of "autosomally recessive". Both copies of a gene must be faulty for you to have the illness, which means both parents must carry a faulty copy. It's possible that neither of them have the disease themselves and they might not know they "carry" a faulty copy.
How likely you are to pass on or inherit a condition depends on whether it is recessive or dominant.
How do you know if you have an inherited condition?
Some blood fat conditions have signs and symptoms such as small yellow lumps on the skin or tendons where fat has collected known as xanthoma. Tests to find the cause can then lead to a diagnosis.
Sometimes people don’t have any symptoms at all so they don’t know they have a condition. If people in your family have had heart disease or a stroke early in life this can be a sign that they have a genetic condition.
Getting a diagnosis
Your doctor can make a diagnosis using:
- blood tests to look at your blood fats
- checking for signs and symptoms
- questions about health problems in your family (known as your family history)
- genetic tests, which can be used to look for the genes involved and confirm a diagnosis.
You might have tests at a specialist centre known as a lipid clinic.
Genetic testing is where specialists look in detail at your genes to look for changes which cause disease. It can confirm a diagnosis and give your doctors details about which genes are involved so they can tailor the treatment for you.
Genetic tests also make it possible to test for the same condition in your extended family so that they can get diagnosed and start treatment. This is called cascade testing.
Genetic testing is currently available for some inherited conditions, but not all.
Treatments for inherited conditions
The treatments depend on which condition you have and how it’s affecting your body. There are a number of treatments available for blood fat conditions and your specialist will talk to you about which ones may be suitable for you.
If you're planning to have a baby
If you have a genetic cholesterol condition such as FH and you’re planning to have a child, the child might inherit the condition too. Your specialist will talk to you about this and might discuss genetic testing.
Getting diagnosed early means your child can start treatment and learn how to look after their health early on, before any problems develop.
Your specialist will talk to you about what the best treatment options are and when it’s a good time to start treatment.
Watch the webinar
HEART UK discuss the relationship between genetics and cholesterol.