Familial Chylomicronemia Syndrome (FCS)

What is FCS?

Familial chylomicronemia syndrome (FCS) is a rare, hereditary condition characterized by a lack of properly functioning lipoprotein lipase (LPL). LPL is an enzyme that plays a critical role in breaking down fat in the form of triglycerides, which are carried from various organs to the blood by lipoproteins. When LPL breaks down these triglycerides, the fat molecules are used by the body as energy or stored in tissue for future use. For those with FCS, this disruption of enzyme activity leads to very high concentrations of triglycerides, especially chylomicrons in the plasma. An estimated 1 in 1 million people have FCS, but due to misdiagnoses and non-diagnoses, that number is likely higher.

What are the symptoms of FCS?

• Pancreatitis
• Skin lesions known as eruptive xanthoma
• A milky appearance of the retinal blood vessels
• abnormal enlargement of the liver and/or spleen
• Nerve damage, such as loss of feeling in the feet or legs
• Memory loss

What causes FCS?

FCS is a genetic disorder. It is caused by an autosomal, recessive genetic defect. Both parents must carry the mutation, and both must pass it onto the child. If both parents have the mutation, there is a 25% chance the child will develop FCS.

How is FCS diagnosed?

FCS often goes undetected or misdiagnosed as hypertriglyceridemia during childhood. Patients usually aren’t properly diagnosed until there are young adults, usually as a result of severe pancreatitis. There is no clear diagnostic profile for FCS, so current clinical practice is mostly based on:

• Clinical findings
• Time of onset
• Family history
• Lipid profile by ultracentrifugation
• Family history of lipid disorders
• Personal history of abdominal pain or pancreatitis
• Milky looking blood sample (fasting lactescent plasma)

What treatments are available for FCS?

There is currently no approved pharmacotherapy in the United States to treat FCS. However, a fat-free, alcohol-free diet is required to manage symptoms.

Where can I find out more about FCS?

• NIH
• FCS Connect
• Rare Disease Report