Homozygous Familial Hypercholesterolemia

What is Homozygous Familial Hypercholesterolemia?

Homozygous familial hypercholesterolemia is an extremely rare genetic disorder that causes dangerously high cholesterol levels from birth. People with this condition inherit two defective genes, one from each parent, that prevent the body from properly removing LDL cholesterol from the blood. This results in total cholesterol levels that typically range from 500 to 1,000 mg/dL or higher, compared to normal levels under 200 mg/dL.

This condition affects roughly 1 in 160,000 to 1 in 1,000,000 people worldwide. Without treatment, the extreme cholesterol buildup causes severe cardiovascular disease in childhood or adolescence. Early recognition and aggressive treatment are essential to prevent heart attacks, strokes, and other life-threatening complications before age 20.

This is different from the more common heterozygous familial hypercholesterolemia, where only one defective gene is inherited. The homozygous form is far more severe and requires immediate medical intervention. Regular monitoring through blood testing helps track cholesterol levels and guide treatment decisions.

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Symptoms

Visible cholesterol deposits called xanthomas on skin, tendons, and knuckles
Yellowish deposits around the eyelids called xanthelasmas
White or gray ring around the cornea called corneal arcus
Chest pain or angina in children and young adults
Heart murmurs detected during physical examination
Narrowing of major arteries causing reduced blood flow
Shortness of breath during physical activity
Swelling of the aortic valve leading to stenosis

Many children show visible signs like skin deposits before age 10. However, some cardiovascular changes may develop silently until a serious cardiac event occurs. Early blood testing is critical for diagnosis before symptoms become life-threatening.

Causes and risk factors

Homozygous familial hypercholesterolemia is caused by inheriting two copies of a mutated gene, one from each parent. The most common mutations affect the LDLR gene, which provides instructions for making LDL receptors that remove cholesterol from the bloodstream. Other genetic mutations can affect the APOB gene or PCSK9 gene. When both gene copies are defective, LDL receptors function at less than 2% of normal capacity or are completely absent.

This is a purely genetic condition, not caused by lifestyle factors. Parents who each carry one defective gene typically have heterozygous familial hypercholesterolemia with moderately elevated cholesterol. When two carriers have children together, each child has a 25% chance of inheriting both defective genes. Family history of very high cholesterol and early heart disease is the primary risk factor for this condition.

How it's diagnosed

Diagnosis begins with a blood test measuring total cholesterol and LDL cholesterol levels. Children with homozygous familial hypercholesterolemia typically show total cholesterol levels above 500 mg/dL from birth. Rite Aid offers comprehensive cholesterol testing that can identify extremely elevated levels requiring further investigation. If initial screening reveals severely high cholesterol in a child or young adult, genetic testing confirms the diagnosis by identifying specific gene mutations.

Additional diagnostic tests include physical examination for visible cholesterol deposits and cardiac imaging to assess heart and blood vessel damage. Early detection through routine blood testing is essential because treatment must begin as soon as possible. Family screening is recommended when one person is diagnosed, as siblings and relatives may also carry mutations.

Treatment options

LDL apheresis, a procedure similar to dialysis that filters cholesterol from blood every 1 to 2 weeks
PCSK9 inhibitor medications like evolocumab or alirocumab given by injection
High-dose statin medications such as atorvastatin or rosuvastatin
Ezetimibe to reduce cholesterol absorption in the intestines
Lomitapide, a medication that reduces cholesterol production in the liver
Evinacumab, a newer medication approved specifically for homozygous familial hypercholesterolemia
Liver transplantation in severe cases to restore normal LDL receptor function
Heart-healthy diet low in saturated fat and cholesterol
Regular cardiovascular monitoring including echocardiograms and stress tests
Avoidance of smoking and maintenance of healthy body weight

Frequently asked questions

Homozygous familial hypercholesterolemia means inheriting two defective genes, one from each parent, causing extremely high cholesterol levels from birth. Heterozygous familial hypercholesterolemia means inheriting only one defective gene, resulting in moderately elevated cholesterol levels. The homozygous form is much rarer and far more severe, requiring aggressive treatment starting in childhood.

This condition can be detected through blood testing at birth or in early infancy. Total cholesterol levels are typically above 500 mg/dL from birth. Visible signs like skin deposits may appear before age 10. Early detection through newborn screening or family history awareness is critical for starting treatment immediately.

No, lifestyle changes alone cannot adequately control cholesterol levels in homozygous familial hypercholesterolemia. This condition requires aggressive medical treatment including medications and often LDL apheresis. Diet and exercise provide supporting benefits but cannot replace medical interventions. Without intensive treatment, the condition leads to cardiovascular disease in childhood.

LDL apheresis is a procedure that filters cholesterol from the blood, similar to dialysis for kidney disease. Blood is removed from the body, passed through a machine that removes LDL cholesterol, and then returned. Most patients require this procedure every 1 to 2 weeks for life. It can reduce LDL cholesterol by 50 to 70% with each treatment.

Total cholesterol levels typically exceed 500 mg/dL in children with homozygous familial hypercholesterolemia, often reaching 700 to 1,000 mg/dL or higher. LDL cholesterol alone is usually above 400 mg/dL. These levels are present from birth and remain extremely elevated without treatment. Normal total cholesterol should be below 200 mg/dL.

There is no cure for homozygous familial hypercholesterolemia, but treatment can significantly lower cholesterol and prevent complications. Liver transplantation can restore normal cholesterol metabolism but carries surgical risks. Most patients require lifelong treatment with medications and apheresis. Gene therapy approaches are being researched but are not yet available.

Without treatment, homozygous familial hypercholesterolemia causes severe cardiovascular disease in childhood or adolescence. Heart attacks can occur before age 20 and are common before age 30. Aortic valve disease, coronary artery blockages, and stroke develop rapidly. Untreated cases often result in death in the first or second decade of life.

Yes, parents can undergo genetic testing to determine if they carry mutations associated with familial hypercholesterolemia. Blood cholesterol testing can also identify carriers who typically have moderately elevated levels. If both parents are carriers, genetic counseling is recommended before or during pregnancy. Prenatal or newborn testing can identify affected children early.

People with this condition require frequent cholesterol monitoring, often every 3 to 6 months or more frequently when adjusting treatment. Regular testing helps doctors assess treatment effectiveness and make necessary medication adjustments. Testing before and after apheresis procedures tracks cholesterol reduction. Lifelong monitoring is essential to prevent complications.

Several newer medications have been approved in recent years including PCSK9 inhibitors, lomitapide, and evinacumab. Evinacumab received FDA approval in 2021 specifically for homozygous familial hypercholesterolemia. These medications provide additional treatment options beyond traditional statins and apheresis. Ongoing research continues to develop gene therapies and other innovative approaches.