Familial chylomicronemia syndrome (FCS) is an inherited genetic disorder that affects how your body breaks down fat. Skin changes, nausea, fever, and recurrent bouts of pancreatitis are common symptoms of this condition.
Familial chylomicronemia syndrome (FCS) is passed down from both parents. It stops the body from properly breaking down fat, leading to a buildup in the bloodstream that can affect the whole body.
FCS is a rare genetic condition. The National Pancreas Foundation reports it’s estimated that it only occurs in 1 out of every 1 to 2 million people, but it can affect anyone of any gender or ethnicity.
FCS is a genetic disorder. It’s an autosomal recessive condition that follows a biallelic inheritance pattern.
This means the genes responsible for FCS are autosomal, located on one of your non-sex chromosomes, and you need two mutated copies (one from each parent) to develop FCS.
FCS occurs when each of your parents passes on a mutated copy of one or more genes involved in triglyceride metabolism.
Most cases of FCS —
After you eat, your small intestine processes dietary fats and combines them into chylomicrons. Chylomicrons carry triglycerides into the bloodstream and throughout the body so they can be used by your tissues as energy or placed in fat storage.
Lipoprotein lipase is necessary to break down chylomicrons into free fatty acids for use. When you don’t make enough of that enzyme due to FCS, chylomicrons accumulate in your bloodstream, leading to high triglyceride levels and other health complications.
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The symptoms of FCS can appear throughout your body and can affect both your physical and mental health.
Clinically, FCS causes high fasting triglyceride levels above 750 mg/dL (41.63 mmol/L). This can make your blood plasma appear milky-white and may also cause lipemia retinalis (a milky appearance in the retinal blood vessels of your eyes).
Too many triglycerides in the bloodstream can reduce blood flow and cause inflammation. Triglycerides can also deposit in tissues like the skin, leading to visible rash-like changes.
Your pancreas is one of the organs most affected by FCS because of its role in fat metabolism. The blood vessels of the pancreas typically contain LPL to break down incoming chylomicrons. In FCS, the chylomicrons accumulate in your pancreas and cause inflammation and damage over time.
Recurrent pancreatitis, episodes where your pancreas becomes inflamed, is a potentially life threatening complication of FCS.
Other possible symptoms include:
- abdominal pain
- nausea
- diarrhea or constipation
- bloating
- physical weakness
- fatigue
- trouble concentrating
- memory problems
- eruptive xanthomas (rash-like bumps on the skin)
- hepatosplenomegaly (enlargement of the liver and the spleen)
According to an interview-based
- abdominal pain
- gastrointestinal symptoms
- fatigue
- problems with memory and thinking
A diagnosis of FCS is confirmed using genetic and clinical testing. Your doctor will check your fasting triglyceride levels and review your personal and family medical history for signs that support an FCS diagnosis, such as recurrent pancreatitis or persistent abdominal pain.
If your fasting triglyceride levels come back as elevated and don’t respond to standard therapies, it can suggest the possibility of an inherited disorder. FCS-specific gene panel sequencing will screen for the known genetic mutations associated with FCS.
Very rarely, genetic testing may come back negative for the known genetic mutations underlying FCS, even if you do live with this condition.
Due to the complex nature of genetics and genetic interactions, it’s possible for yet undiscovered mutations and genetic variants
The goal of FCS management is to lower your triglyceride levels, but medications traditionally used to lower triglyceride levels
However, in 2024, olezarsen (Tryngolza) became the first drug the
Dietary modification of fat intake is a critical part of FCS management. The Endocrine Society reports that it’s necessary that you limit your daily fat intake to less than 10% to 15% of your daily calories, which means consuming no more than a total of 20 grams of fat each day.
Because each person’s health needs can be different, you may need to work closely with a multidisciplinary medical team that can include the following medical professionals:
- primary doctor
- genetic counselor
- endocrinologist (doctor who specializes in hormone-related conditions)
- dietitian
Diet modifications for FCS can go beyond basic fat intake management. You may need to alter your food choices or incorporate different types of fats, such as medium-chain triglycerides, which are not incorporated into chylomicrons.
Medium-chain triglycerides are naturally found in many foods, including milk fat, coconut oil, and palm kernel oil.
If you’re on other medications for coexisting conditions, these may also need adjustments. Some medications, such as beta-blockers,
Currently, there’s no cure for FCS, but treatment involving medications and lifestyle adjustments can help manage your triglyceride levels and prevent the systemic effects of FCS.
Without effective treatment, FCS can significantly affect your quality of life. It can cause debilitating, life threatening symptoms and
FCS is an inherited genetic condition that prevents your body from metabolizing triglycerides effectively. When your triglycerides get too high for too long, they can cause serious health complications like pancreatitis and can lead to other health complications like heart disease.
While there’s currently no cure for FCS, medication and lifestyle modifications — particularly around diet — can help improve your overall quality of life.