Rare Disease Day - FH Europe Foundation

What is a Rare Disease?

A rare disease is a medical condition that affects a small percentage of the population, often defined as fewer than 1 in 2,000 people in many regions. These diseases are typically chronic, progressive, and may be life-threatening, with symptoms that are often complex or difficult to diagnose. Many rare diseases have a genetic basis, although some can result from infections, environmental factors, or autoimmune processes.

While each condition is uncommon on its own, collectively rare diseases affect an estimated 300 million people worldwide, presenting unique challenges for patients, carers, and healthcare systems. Because of their low prevalence, research, treatment options, and awareness are frequently limited, making early diagnosis and specialised care especially important.

What is Rare Disease Day?

Rare Disease Day, held every year on the last day of February, is a global movement dedicated to raising awareness and championing the rights of people living with rare diseases and their families. Launched in 2008 by EURORDIS (the European Organisation for Rare Diseases), and coordinated alongside 60 national patient alliances, the day unites patients, carers, healthcare professionals, researchers, and organisations worldwide. It is a powerful opportunity to share stories, highlight challenges, and drive action to improve diagnosis, care, and support for those affected by rare diseases.

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At FH Europe Foundation, Rare Disease Day is an important date in our calendar, providing an opportunity to raise awareness for Homozygous Familial Hypercholesterolaemia (HoFH) and Familial Chylomicronaemia Syndrome (FCS)

What is HoFH?

HoFH (homozygous familial hypercholesterolaemia) is a rare and severe form of FH, affecting approximately 1 in 300,000 people worldwide. It occurs when a child inherits two altered FH-causing genes, one from each parent.

If untreated, individuals with HoFH typically have extremely high LDL-cholesterol levels, ranging from 400 to 1000 mg/dL (4 to 10 times the normal level). Without diagnosis and management, HoFH can lead to early-onset cardiovascular complications, including heart disease and aortic valve disease, sometimes appearing in childhood.

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What is FCS?

FCS (familial chylomicronaemia syndrome) is a rare genetic disorder caused by the inability to properly metabolise dietary fat due to defective or absent lipoprotein lipase (LPL) or related components. This leads to high levels of chylomicrons and triglycerides in the blood, resulting in symptoms that vary in severity based on these levels.

FCS is an autosomal recessive condition, requiring two altered genes—one from each parent. Most cases are due to mutations in genes coding for LPL or apolipoprotein C-II, a cofactor necessary for LPL function. Symptoms typically appear in childhood or adolescence but may arise later depending on the genetic mutation.