Most cases of high cholesterol develop gradually over a lifetime — shaped by diet, physical activity, weight, and age. But for roughly 1 in 200 to 300 people, high LDL cholesterol is not a lifestyle consequence. It is hardwired into their DNA from the moment they are born.

This is familial hypercholesterolaemia — commonly abbreviated as FH — a genetic condition that causes LDL cholesterol levels to be significantly elevated from birth, independent of how well a person eats or exercises. Without diagnosis and treatment, people with FH are exposed to decades of elevated LDL, dramatically increasing their lifetime risk of heart attack, stroke, and other cardiovascular events — often at a younger age than the general population would expect.

The challenge is that FH is widely underdiagnosed. In Singapore, as in most countries, the majority of people living with FH do not know they have it.

What Is Familial Hypercholesterolaemia?

Familial hypercholesterolaemia is caused by a mutation in one of several genes involved in how the body processes LDL cholesterol. The most commonly affected gene is LDLR, which provides instructions for producing LDL receptors on liver cells. These receptors are responsible for removing LDL from the bloodstream. When the LDLR gene is mutated, fewer functioning receptors are made, and LDL accumulates in the blood.

Less commonly, mutations in the APOB gene (which affects how LDL binds to its receptor) or the PCSK9 gene (a gain-of-function variant that causes too many LDL receptors to be degraded) can produce the same clinical picture.

FH is inherited in an autosomal dominant pattern. This means that inheriting just one copy of the mutated gene from one parent is enough to cause the condition. Each child of an affected parent has a 50% chance of inheriting FH.

How Common Is FH in Singapore?

Global prevalence estimates suggest FH affects approximately 1 in 200 to 300 people — making it one of the most common inherited metabolic disorders. Applied to Singapore's population, this translates to an estimated 18,000 to 27,000 individuals living with FH, the vast majority of whom are unaware of their diagnosis.

FH does not preferentially affect any single ethnic group. It is present across Chinese, Malay, Indian, and other communities in Singapore.

Why FH Is So Often Missed

Several factors contribute to the persistent underdiagnosis of FH:

No obvious early symptoms. High LDL from FH does not cause pain or visible symptoms in most people until cardiovascular damage has already occurred. A person with FH may feel entirely healthy for decades while their arteries are silently accumulating cholesterol plaques.

Physical signs are not universal. Certain physical findings can suggest FH — including xanthomas (cholesterol deposits in tendons, particularly the Achilles tendon), xanthelasmas (yellowish deposits around the eyelids), and corneal arcus (a white or grey ring around the cornea in younger patients). However, these signs are absent in many people with FH, particularly those with heterozygous FH.

Confusion with diet-related high cholesterol. When a high LDL result is found, it is often attributed initially to lifestyle factors. Without a careful family history, a clinician may not suspect a hereditary cause, especially if the patient is young and otherwise appears healthy.

Family history not asked or not known. A key diagnostic clue for FH is a family history of premature cardiovascular disease or very high cholesterol in close relatives. This history is often not volunteered or explored in a routine consultation.

How FH Is Diagnosed

There is no single definitive test. Diagnosis is typically made by combining three elements: the degree of LDL elevation, personal and family history, and physical examination. The Dutch Lipid Clinic Network (DLCN) criteria provide the most widely used scoring framework:

A total score of ≥6 points is classified as probable or definite FH. A score of 3–5 suggests possible FH and warrants further evaluation.

Genetic testing can confirm the diagnosis by identifying the causative mutation but is not required if the clinical picture is clear. In Singapore, genetic testing for FH is available through specialist centres and is particularly valuable for enabling cascade screening of family members.

Heterozygous vs. Homozygous FH: Understanding the Difference

Heterozygous FH (HeFH) — by far the more common form — occurs when one copy of the gene is mutated. Untreated LDL cholesterol typically ranges from 5.0 to 10.0 mmol/L. Without treatment, men with HeFH face a roughly 50% risk of coronary heart disease by age 50; in women the risk is elevated but somewhat delayed.

Homozygous FH (HoFH) occurs when mutations are inherited from both parents and is far rarer — affecting approximately 1 in 300,000 to 1,000,000 people. LDL cholesterol in HoFH is typically above 13 mmol/L and can exceed 20 mmol/L in severe cases. Without aggressive treatment, cardiovascular events can occur in adolescence or even childhood. HoFH is managed in specialist tertiary centres and may require advanced interventions such as lipoprotein apheresis.

The remainder of this article focuses primarily on heterozygous FH, which accounts for the overwhelming majority of FH cases seen in general practice.

Why FH Requires a Different Treatment Approach

For most people with high cholesterol, a lifestyle overhaul — reducing saturated fat, increasing exercise, losing weight — can meaningfully lower LDL. For people with FH, this is not the case.

Because the problem is a structural deficiency in LDL receptor function rather than excessive LDL production from lifestyle factors, dietary and lifestyle improvements alone are insufficient to normalise LDL in FH. They remain important as adjuncts to medication, but medication is non-negotiable and almost always required from the time of diagnosis.

This is why early diagnosis matters so much. Every year that elevated LDL goes untreated in a person with FH represents accumulated cardiovascular risk that cannot be fully reversed. Beginning treatment early — including in adolescence in appropriate cases — reduces lifetime exposure to elevated LDL and significantly improves long-term outcomes.

For a broader understanding of how LDL cholesterol contributes to cardiovascular risk even outside of FH, read our high LDL cholesterol guide →.

Treatment Options for FH in Singapore

Treatment for HeFH follows a stepwise approach, with the goal of achieving guideline-recommended LDL targets. For most patients with FH who do not have established cardiovascular disease, the target is LDL below 2.5 mmol/L. For those with FH who have already had a cardiovascular event, the target is more stringent — LDL below 1.4 mmol/L.

Step 1: High-Intensity Statin Therapy

High-intensity statins — typically rosuvastatin or atorvastatin at maximum tolerated doses — are the cornerstone of FH treatment. They can reduce LDL by 40 to 55%, but in FH patients starting with very high LDL levels, this reduction is often not sufficient on its own to reach target.

Step 2: Ezetimibe

Adding ezetimibe to statin therapy provides an additional LDL reduction of approximately 15 to 25% through a different mechanism — blocking cholesterol absorption in the intestine. Combination therapy is standard for most FH patients.

Step 3: PCSK9 Inhibitor Therapy

For the substantial proportion of FH patients who cannot reach their LDL target on maximum statin plus ezetimibe — or for those with statin intolerance — PCSK9 inhibitor therapy is the most effective next step available.

PCSK9 inhibitors work by blocking the PCSK9 protein, which normally degrades LDL receptors on liver cells. By inhibiting PCSK9, more LDL receptors remain functional, dramatically increasing the liver's capacity to clear LDL from the bloodstream. In clinical trials, PCSK9 inhibitors have consistently achieved 50 to 60% additional LDL reduction on top of background therapy — making them particularly impactful for FH patients with high baseline LDL levels.

They are administered as a subcutaneous injection every two or four weeks depending on the formulation, and are available in Singapore for patients who meet clinical criteria.

For a full explanation of how PCSK9 inhibitor therapy works, what to expect, and who qualifies, read our dedicated guide to PCSK9 inhibitors in Singapore →.

Cascade Screening: Protecting Your Family

Because FH is inherited in an autosomal dominant pattern, a diagnosis in one family member carries direct implications for close relatives. Each first-degree relative — parent, sibling, or child — of someone with confirmed FH has a 50% probability of also having FH.

Cascade screening refers to the systematic testing of family members once a proband (the first identified case in a family) is diagnosed. It is endorsed by cardiovascular guidelines internationally and in Singapore as the most cost-effective way to identify FH cases before cardiovascular damage occurs.

If you have been diagnosed with FH, your doctor can help coordinate testing for your immediate family. Early diagnosis in relatives — including children — allows treatment to begin before decades of elevated LDL have accumulated.

Children of a parent with FH should be screened no later than age 10, or earlier if the family history suggests a particularly severe presentation.

Frequently Asked Questions

Can FH be cured?

No. FH is a lifelong genetic condition. Medications can effectively control LDL and dramatically reduce cardiovascular risk, but they do not correct the underlying gene mutation. Treatment must be continued long-term.

If I eat a very healthy diet, can I manage FH without medication?

No. Lifestyle modifications are important and should be maintained, but they are not sufficient to normalise LDL in FH. The LDL elevation in FH is driven by a genetic defect in LDL receptor function, not primarily by dietary intake. Medication is required.

At what age should children be tested for FH?

If a parent has confirmed FH, children should be screened by age 10, or earlier if there is a strong family history of very early cardiovascular disease. Statin therapy is appropriate for children with FH from age 8 to 10 in high-risk cases, under specialist guidance.

Is FH treatment covered by Medisave or MediShield Life in Singapore?

Coverage depends on the specific medications prescribed and the clinical context. Your doctor can advise on the available subsidy and insurance frameworks for your treatment plan.

I have no symptoms. Do I still need to treat my FH?

Yes. The absence of symptoms does not mean the arteries are unaffected. Cholesterol plaque accumulates silently over years. The purpose of treatment is to prevent the first cardiovascular event — not to wait until symptoms appear.

Final Thoughts

Familial hypercholesterolaemia is not rare — it is simply underdiagnosed. For anyone with a very high LDL result, a personal or family history of premature cardiovascular disease, or physical signs like tendon xanthomas, FH should be part of the clinical conversation.

The good news is that with early diagnosis and appropriate treatment — including PCSK9 inhibitor therapy where standard treatments fall short — people with FH can achieve substantial reductions in cardiovascular risk and live healthy, full lives. The key is finding it before the heart pays the price.

If you have concerns about your cholesterol levels or a family history of heart disease, visit our high cholesterol service page to learn more about how Nee Soon Clinic can help.

Disclaimer: The information provided in this article is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. The content is not intended to be a comprehensive source of information and should not be relied upon as such. Reliance on any information provided in this article is solely at your own risk. The authors and the publisher do not endorse or recommend any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned in the article. Any reliance on the information in this article is solely at the reader's own risk.

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