Familial Chylomicronaemia Symdrome (FCS)

What is Familial Chylomicronaemia Syndrome (FCS)?

Familial Chylomicronaemia Syndrome is the name for a group of rare genetic disorders that cause very high levels of triglycerides (a kind of fat) in the blood. High triglycerides can cause serious health problems in the long term, such as pancreatitis. But with a very low fat diet, you can help to avoid them. 

Familial Chylomicronaemia Syndrome is often shortened to FCS.  You might also hear the term Lipoprotein Lipase Deficiency (LPLD), which is the most common type of FCS, or chylomicronaemia.

FCS is very rare, around one to two in a million people have it.

If you have FCS, you have it from the time you’re born. But when the symptoms start and how much they affect you varies from person to person. Sometimes symptoms are more severe and appear in childhood or infancy. Sometimes they appear in adolescence or childhood so so you might get a diagnosis later on. 

Learn about other inherited cholesterol conditions

Learn more

What are the symptoms of FCS?

  • regular bouts of pain in the abdomen (stomach area) – this can be mild or severe
  • pain in the joints
  • small, raised, fat-filled spots on the skin (called eruptive xanthomata) – these often appear on the buttocks, knees and arms, and improve when triglyceride levels are lowered
  • fatty stools (known as steatorrhoea) – which appear pale and oily in appearance, and difficult to flush
  • pale pink arteries and veins in the retina of the eye (called lipaemia retinalis) caused by raised triglycerides – which can be spotted by opthalmologists (eye specialists) on eye tests
  • sudden (acute) pancreatitis – which causes pain and swelling around your stomach, feeling and being sick, fever or chills, and jaundice (yellowing of the eyes and skin), this can be very serious (see below)  
  • an enlarged liver or spleen – which causes pain  
  • extreme tiredness (known as fatigue) – due to a lack of energy, you might also have fatigue after a meal
  • problems with memory and concentration
  • low mood (depression) – which could be due to a lack of energy, the recurring symptoms, and the challenges of eating a restrictive diet. 

What are the long-term effects of FCS? 


The pancreas is a vital organ. It makes some of the enzymes needed for digestion and the hormones insulin and glucagon which control your blood sugar.

FCS causes episodes of pancreatitis, where the pancreas becomes inflamed and swollen. Acute pancreatitis (when it comes on suddenly) can be very serious or life-threatening and needs urgent treatment in hospital.

Repeated attacks of acute pancreatitis can lead to chronic (long term) pancreatitis and can cause permanent damage.  


If you have FCS, you’re more likely to develop type 2 diabetes  – where your blood sugar levels aren’t properly controlled and rise too high – especially if you have repeated bouts of pancreatitis. This is because repeated bouts of pancreatitis can damage the pancreas, and it can’t produce the hormones which are needed to control blood sugar.  

Diabetes can lead to a number of serious health problems including heart disease and kidney disease.

If you develop diabetes your doctor will want to keep your blood sugar levels well controlled. Medications to treat type 2 diabetes include Metformin, sitagliptin and insulin.

Why does FCS raise your triglycerides?

Most people have an enzyme (a type of protein) called lipoprotein lipase in their bodies. It clears triglycerides from their blood after a meal.

If you have FCS, you are missing lipoprotein lipase. Or you only have a very small amount and it might not work properly. Without this enzyme, the fat can’t be cleared from your blood and your triglyceride levels stay high, making the blood appear creamy white.  

What does Chylomicronaemia mean?

Triglycerides in the blood are packaged into balls called chylomicrons. So, the ‘Chylomicronaemia’ part of the name Familial Chylomicronaemia Syndrome simply means there’s too many chylomicrons in the blood. In other words, there’s too much fat.

What causes FCS?

The ‘Familial’ part of ‘Familial Chylomicronaemia Syndrome’ means the condition is passed down through families. It’s genetic.
There are five different genes known to be involved in FCS. A fault in any of these genes can cause FCS.

How is it passed on through families?
We have two copies of every gene, one from each parent. Both copies of a gene involved in FCS need to be faulty for you to inherit it.

If you only have one faulty copy of a gene, you won’t have FCS but you will be a carrier. 
Carriers don’t have FCS or symptoms but might have slightly higher blood fats and so a slightly higher risk of heart disease. There are tests to find out if you’re a carrier.

If you have FCS, you will pass on a faulty gene to any children you have, so they will be a carrier.They will only have FCS themselves if they also inherit a faulty gene from the other parent. 

How is FCS diagnosed?

Most people with FCS are diagnosed as babies or young children, before the age of 10, because they have symptoms such as tummy pain, pancreatitis and fat-filled spots. It can be diagnosed with blood samples, which will be a creamy colour with very high triglycerides. 

For other people, the symptoms appear later so they’re diagnosed later, in their 20s, 30s and 40s. Some women only show symptoms during pregnancy when blood fats naturally rise, and the FCS means they rise even higher.

Because FCS is so rare, some people don’t get a formal diagnosis until they’re teenagers or adults even if they symptoms start in childhood. Sometimes people live with the symptoms for years, and sometimes people are misdiagnosed.

These days, more and more people are being diagnosed using a genetic test. The test looks for problems with the genes that code for lipoprotein lipase and the other proteins that work with it.  

With FCS, your triglycerides levels will usually be over about 10mmol/litre.

Treatments for FCS

Eat a very low fat diet

The main treatment for FCS is through diet.

It needs to be very low in fat, limited in simple sugars and refined carbohydrates, and low in alcohol. This stops your triglycerides in your blood from rising.

Check out our plan for healthy eating for FCS where you can learn about all the things you can eat to stay healthy, with lots of tips to help you get started.

Eating for FCS  Eating for FCS recipes


Medicines for FCS

The medicines which are usually used to lower blood fats, such as statins and fibrates, don’t help with FCS. That’s because they depend on lipoprotein lipase working properly.
There are some medications available but they only have a small effect. But new medicines for FCS are being researched and developed at the moment.


Volanesorsen is a new treatment which can be used alongside a very low fat diet to lower triglycerides in the blood. You take it as an injection.

Volanesorsen works by lowering the levels of a protein in your blood called Apo-CIII. This protein normally raises triglycerides in a number of different ways. One way is by stopping the enzyme lipoprotein lipase from working properly, which interferes with trigylcerides being cleared from the blood. So by lowering this protein, volanesorsen also lowers your triglycerides.

NICE (the National Institute for Health and Care Excellence) who make the guidelines UK health professionals, will consider whether it should be made available for people in the UK in late 2019.

Living with FCS

Dealing with your diagnosis

FCS can have a big effect on your life. Getting a diagnosis and living with the symptoms can be hard. Some people say they feel very low, anxious or depressed.

People with FCS will often have episodes of pain and pancreatitis throughout their lives even if they stick to a low fat diet. These episodes can come on without warning, and pancreatitis can leave you tired or fatigued for a long time afterwards.

It’s important to acknowledge how FCS affects you and how you feel about it – this is a big part of accepting it and being able to move forwards with your life.

Understanding your condition

One of the best things you can do to look after yourself is to get a really good understanding of how FCS affects you, what you can and can’t eat and anything else you can do to look after yourself. 
It can give you the motivation and knowledge to choose foods stick to the foods that will keep you healthy, and the knowledge you need to choose these foods. 

Eating a very low fat diet

A low fat diet is the key to living with FCS and keeps the chances of pain and pancreatitis as low as possible. It can be very challenging because food is such a big part of our lives, and our social lives too. Get some practical information in our section about eating and FCS. 

Looking after yourself 

As well as keeping your blood fats under control, take care of yourself in other ways to lower the risk of diabetes, heart disease and other conditions.

Keeping to a healthy weight, being physically active, avoiding alcohol and smoking will all help to keep you blood fats and blood pressure healthy.

Working with your doctor

Because FCS is so rare, most consultants only ever see a few people with it. You are the expert on your own body, and with time you will become an expert in FCS and how it affects you. Work with your specialist doctor to find the diet and treatments that works best for you. 

You are not alone 

FCS is very rare. Only around 55 – 110 people in England have it.  This means people don’t understand it. Which, combined with having to eat different things, can feel very isolating.

The truth is you are not alone, there are others with FCS and other conditions which affect what you can eat. There are also others you can talk to help you deal with your condition and any changes you need to make.

  • Speak to your specialist doctor or nurse. They are experienced in working with people with blood fat conditions and can talk to you about what it’s like for you and things that can help.
  • Call or email our Cholesterol Helpline to speak to dietitian who and can help you make changes to your diet. Their advice is to support rather than replace any advice you have been given by your own dietitian.
  • Seeing a counsellor, therapist or coach can also give you the chance to speak to someone about how your condition is affecting you and find strategies to deal with it. Some people find Cognitive Behavioural Therapy (CBT) helpful. Speak to your GP about what’s available on the NHS or visit the British Association for Counselling and Psychotherapy.


Getting advice for women

FCS affects women differently to men because of differences in our hormones. If you are female, speak to your specialist doctor about any medicines which might not be suitable for you such as contraceptions and hormone replacement therapy, or if you are planning to get pregnant. 

If your child has FCS

If your child has FCS, they will probably be referred to a pediatrician (a doctor who specialises in working with children) with knowledge of blood fat conditions. They will be able to talk to you about how to keep your child healthy throughout their lives.  


Raising awareness

At HEART UK we are calling on the government and NHS to improve awareness of FCS and improve access to services and support; including dietetic, emotional and mental health support.