Familial lipoprotein lipase deficiency

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Familial lipoprotein lipase deficiency is an inherited condition that disrupts the normal breakdown of fats in the body, resulting in an increase of certain kinds of fats.

People with familial lipoprotein lipase deficiency typically develop signs and symptoms before age 10, with one-quarter showing symptoms by age 1. The first symptom of this condition is usually abdominal pain, which can vary from mild to severe. The abdominal pain is often due to inflammation of the pancreas (pancreatitis). These episodes of pancreatitis begin as sudden (acute) attacks. If left untreated, pancreatitis can develop into a chronic condition that can damage the pancreas and, in rare cases, be life-threatening.

Affected individuals may also have an enlarged liver and spleen (hepatosplenomegaly). The higher the levels of fat in the body, the larger the liver and spleen become. As fat levels rise, certain white blood cells called macrophages take in excess fat in an attempt to rid fat from the bloodstream. After taking in fat, the macrophages travel to the liver and spleen, where the fatty cells accumulate.

Approximately half of individuals with familial lipoprotein lipase deficiency develop small yellow deposits of fat under the skin called eruptive xanthomas. These fat deposits most commonly appear on the trunk, buttocks, knees, and arms. Eruptive xanthomas are small (about 1 millimeter in diameter), but individual xanthomas can cluster together to form larger patches. They are generally not painful unless exposed to repeated friction or abrasion. Eruptive xanthomas begin to appear when fat intake increases and levels rise; the deposits disappear when fat intake slows and levels decrease.

The blood of people with familial lipoprotein lipase deficiency can have a milky appearance due to its high fat content. When fat levels get very high in people with this condition, fats can accumulate in blood vessels in the tissue that lines the back of the eye (the retina). The fat buildup gives this tissue a pale pink appearance when examined (lipemia retinalis). This fat accumulation does not affect vision and will disappear once fats from the diet are reduced and levels in the body decrease.

In people with familial lipoprotein lipase deficiency, increased fat levels can also cause neurological features, such as depression, memory loss, and mild intellectual decline (dementia). These problems are remedied when dietary fat levels normalize.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the LPL gene cause familial lipoprotein lipase deficiency. The LPL gene provides instructions for producing an enzyme called lipoprotein lipase, which is found primarily on the surface of cells that line tiny blood vessels (capillaries) within muscles and fatty (adipose) tissue. This enzyme helps break down fats called triglycerides, which are carried by molecules called lipoproteins.

Mutations that cause familial lipoprotein lipase deficiency lead to a reduction or elimination of lipoprotein lipase activity, which prevents the enzyme from effectively breaking down triglycerides. As a result, triglycerides attached to lipoproteins build up in the blood and tissues, leading to the signs and symptoms of familial lipoprotein lipase deficiency.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Researchers speculate that if family members of affected individuals have a mutation in one copy of the LPL gene in each cell, they may have a mild increase in fat levels in the blood, which could increase their risk of health problems such as heart disease or diabetes. However, studies have not clearly demonstrated whether these individuals are more prone to develop these health problems than individuals in the general population.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

This condition affects about 1 per million people worldwide. It is much more common in certain areas of the province of Quebec, Canada.

Which doctor should you see?

The suggested department for discussing Familial lipoprotein lipase deficiency is Endocrinology, with a endocrinologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which hormone or metabolic finding is important in this case?
• How should test timing and current medicines be taken into account?
• What follow-up would show whether the care plan is working?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.