Familial Chylomicronemia Syndrome (FCS)

FCS affects an estimated 1 in every 1–2 million people of all genders, races, and ethnicities, and it can be diagnosed at any age. It occurs when lipoprotein lipase (LPL), the enzyme that breaks down triglycerides, is missing or doesn’t work properly, usually because of mutations in the LPL gene or in related genes. Without working LPL, chylomicrons (the particles that carry triglycerides in the blood) can’t break down and build up instead. This buildup can block blood flow to the pancreas and trigger acute pancreatitis, a painful and potentially life-threatening condition that can cause lasting damage and other complications.

Symptoms of FCS can vary widely but may include:

• Severe abdominal pain: Often associated with pancreatitis, a potentially life-threatening condition.
• Fatty deposits in the skin: Known as eruptive xanthomas, these are small, yellowish bumps often found on the buttocks, arms, and legs.
• Memory and concentration issues: “Brain fog” is common in people living with FCS.
• Enlarged liver and spleen: Caused by fat buildup.
• Chronic tiredness and weakness: Often reported by people with FCS.

Early diagnosis is crucial to managing symptoms and reducing the risk of complications. Diagnosing FCS can include:

• Blood tests: These measure extremely high triglyceride levels (often over 880 mg/dL) and confirm the presence of chylomicrons. When blood is drawn, the plasma may look milky because of the excess lipids.
• Lipid profile: This helps rule out other lipid disorders and narrow down the diagnosis.
• Genetic testing: This identifies mutations in genes related to FCS. Key genes include:
  • LPL: Codes for the enzyme lipoprotein lipase, which breaks down triglycerides.
  • APOA5, GPIHBP1, APOC2, and LMF1: Mutations in these genes can also contribute to FCS.

Talk with a genetic counselor about FCS and whether genetic testing is right for you., https://www.genomemedical.com/individuals/#schedule

There is no cure for FCS. Treatment focuses on lowering triglycerides, managing symptoms, and preventing complications.

Diet: A very low-fat diet (under 10–15% of daily calories) is the cornerstone of treatment. For people with FCS, all fat counts; there is no “good fat.” (See Living with FCS for details.)

FDA-approved medications: Two prescription medicines are approved in the U.S. for adults with FCS, both used together with a low-fat diet:

• Tryngolza (olezarsen): Approved in December 2024, injected once a month.
• Redemplo (plozasiran): Approved in November 2025, self-injected once every three months. In the PALISADE trial, it lowered triglycerides by a median of 80% (vs. 17% with placebo). [link: PALISADE trial]

Fibrates, omega-3s, and niacin are sometimes prescribed but have limited effect in FCS. Omega-3s count toward your daily fat allowance. Talk with an FCS specialist before starting any medication.

Monitoring: You’ll need regular blood tests to track triglycerides and watch for pancreatitis, plus a yearly eye exam.

Care team: Repeated pancreatitis can lead to chronic pancreatitis and pancreatic (type 3c) diabetes, and very high triglycerides can make attacks more severe. A team that understands FCS can help lower these risks. It may include a lipidologist, gastroenterologist or pancreatologist, primary care physician, registered dietitian, and mental health support.

Eating with FCS
High triglycerides are managed with an extremely restrictive low-fat diet, at 10–15% of total daily calories.

• Foods that may fit: vegetables, fruits, whole grains, egg whites, legumes, fat-free dairy, seafood, and lean poultry.
• Essential nutrients: Supplements can provide essential fatty acids, fat-soluble vitamins (A, D, E, K), minerals, and medium-chain triglycerides as needed.
• Meal pattern: Small, frequent meals with fat-free or low-fat protein are suggested.

Recipes

• Know Your TGs – FCS-Friendly Recipes
• Learn Your Lipids – Low-Fat Cookbook
• Action FCS – Recipes
• FCS Foundation Recipes

Lifestyle tips

• Stick to a strict low-fat diet (see above).
• Stay hydrated: Drinking enough water helps reduce blood viscosity.
• Exercise gently: Intense exercise may raise triglycerides, but moderate activities like walking or yoga are beneficial.
• Manage stress: Stress can make symptoms worse, so practices like meditation and deep breathing can help.
• Find support: Group or one-on-one support can help.

Talk with people who get it. Join the Living with FCS community on Facebook: https://www.facebook.com/groups/livingwithfcs/