Familial chylomicronemia syndrome (FCS) is a rare genetic disease characterized by the build up of chylomicrons (chylomicronemia), the largest lipoprotein particle, which are responsible for transporting dietary fat and cholesterol.
1-3 Typically, the enzyme lipoprotein lipase (LPL) breaks down chylomicrons in the blood.
4,5 However, in people living with FCS, LPL does not function properly. This inability to break down chylomicrons
1-3 leads to an increase in triglyceride levels. Normal triglyceride levels are <150 mg/dL (or 1.7 mmol/L). With FCS, triglycerides can rise to 10 times this level, even with medication or a low-fat diet.
4
Patients often present with several severe symptoms before FCS is diagnosed. Many experience pancreatitis, an acute recurrent inflammation of the pancreas, which causes debilitating pain and can be fatal.
6-8 Others develop eruptive xanthomas (fatty deposits on the skin) lipemia retinalis (milky appearance of retinal veins and arteries), abdominal pain, and hepatosplenomegaly (an enlargement of the liver or spleen).
9,10 Patients are also often fatigued, lack energy, have impaired cognition, and develop numbness/tingling that can affect their ability to handle many daily responsibilities.
Due to its rarity and the fact that high levels of triglycerides can be attributed to other causes, such as alcohol consumption, uncontrolled diabetes, or certain medications, FCS is often misdiagnosed or goes undiagnosed. There are currently no approved therapies for the treatment of FCS. In most cases, patients are managed with efforts to strictly reduce the levels of fat in their diet.
Although FCS is very rare, it is known to be more prevalent in certain populations (often referred to as "founder" populations), including French Canadians and certain communities in the Netherlands, where the prevalence of FCS has been shown to be as high as 19 to 20 per 1 million individuals.11
Parents pass the trait for FCS to their children. It is caused by an autosomal, recessive genetic defect or mutation that affects the function or amount of the LPL enzyme. There are several known mutations, likely with others not yet characterized.12,13
Due to the rarity of the condition, the clinical progression of FCS is not well understood. In some cases, patients may develop symptoms, including abdominal pain, early in life, but may not be diagnosed until they are in their teens or 20s and pancreatitis attacks become more frequent.9,10
