Learning about VLCAD can bring many questions.
Explore frequently asked questions about VLCAD, including genetics, diagnosis, treatment, and daily management for individuals and families living with long-chain fatty acid oxidation disorders (LC-FAOD).
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VLCAD deficiency is most commonly identified through routine newborn screening shortly after birth. In many regions, including the United States, newborn screening tests measure specific markers in a baby’s blood that can indicate a possible fatty acid oxidation disorder such as VLCAD. If the screening shows abnormal results, it does not immediately confirm a diagnosis but signals the need for further evaluation.
After an abnormal newborn screen, doctors typically order confirmatory testing to verify whether VLCAD is present. This may include additional blood tests to analyze acylcarnitine levels, which help assess how the body processes fats for energy. Genetic testing is also performed to look for changes in the ACADVL gene, the gene responsible for VLCAD deficiency. Identifying these genetic variants helps confirm the diagnosis and may provide insight into the potential severity of the condition.
In some cases, especially if symptoms appear later in infancy, childhood, or adulthood, VLCAD may be diagnosed after episodes of low blood sugar, muscle breakdown (rhabdomyolysis), fatigue, or cardiac concerns prompt metabolic testing.
A metabolic geneticist or inherited metabolic disorder specialist will then conduct a comprehensive evaluation, which may include lab monitoring, clinical history, and coordination with a metabolic care team. Early and accurate diagnosis is critical because it allows families and healthcare providers to begin dietary management, emergency planning, and ongoing monitoring to reduce the risk of metabolic crises and support long-term health and safety.
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At this time, there is no cure for VLCAD deficiency. However, there have been major advances in treatment and research over the past several years.
Current management focuses on preventing energy shortages in the body by providing consistent nutrition and avoiding triggers such as prolonged fasting. Some individuals may also benefit from specialized therapies that help provide alternative sources of energy.
Researchers around the world are actively studying VLCAD deficiency and other long-chain fatty acid oxidation disorders. Areas of research include:
Improved medications that support energy production
Gene therapy approaches designed to correct the underlying genetic cause
Better dietary therapies and metabolic treatments
Understanding why symptoms vary among individuals
These research efforts aim to improve long-term outcomes and may eventually lead to treatments that address the root cause of the disorder.
Families living with VLCAD today are benefiting from a rapidly growing understanding of the condition, and continued research offers hope for even better therapies in the future.
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Many children with VLCAD deficiency can attend school, participate in activities, and live fulfilling lives with proper medical care, dietary management, and close monitoring. However, VLCAD exists on a spectrum of severity, and not every child’s journey is the same. Some individuals may experience more frequent symptoms, hospitalizations, or activity limitations, especially during illness, growth stages, or periods of increased energy demand. Ongoing care from a metabolic specialist and individualized management plans are essential to support safety, stability, and the best possible quality of life.
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During illness or fasting, the body relies more heavily on fat for energy. Since VLCAD affects fat metabolism, this can lead to rapid energy depletion and medical emergencies.
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No, VLCAD deficiency is a lifelong genetic metabolic disorder and children do not grow out of it. While symptoms and medical needs may change over time, the underlying enzyme deficiency remains throughout life.
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Many children with VLCAD attend school and participate in activities with proper planning, medical support, and individualized care plans. However, activity levels, illness management, and nutrition must be carefully monitored to prevent metabolic crises.
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Yes. VLCAD deficiency is inherited in an autosomal recessive pattern, meaning a child must inherit two altered copies of the ACADVL gene, one from each parent, to develop the condition.
Parents who carry one altered gene are called carriers. Carriers typically do not have symptoms because their second copy of the gene works normally.
What gene causes VLCAD Deficiency?
VLCAD deficiency is caused by mutations in the ACADVL gene.
This gene provides instructions for making the very long-chain acyl-CoA dehydrogenase (VLCAD) enzyme, which helps break down long-chain fatty acids to produce energy in the mitochondria.
When this enzyme does not function properly, the body cannot efficiently convert certain fats into energy.
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VLCAD deficiency is caused by mutations in the ACADVL gene.
This gene provides instructions for making the very long-chain acyl-CoA dehydrogenase (VLCAD) enzyme, which helps break down long-chain fatty acids to produce energy in the mitochondria.
When this enzyme does not function properly, the body cannot efficiently convert certain fats into energy.
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Yes. Most parents who carry one altered ACADVL gene do not have symptoms.
Because carriers are typically healthy, many families do not know they carry the gene until a child is diagnosed through newborn screening or metabolic testing.
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Yes. Because carriers usually have no symptoms, many family members may carry an altered ACADVL gene without realizing it. Genetic testing can help identify carriers within a family.
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VLCAD deficiency was first recognized as a distinct metabolic disorder in 1992, when scientists identified a previously unknown enzyme involved in long-chain fatty acid oxidation.
Shortly after, researchers identified the ACADVL gene responsible for producing the VLCAD enzyme.
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VLCAD deficiency is a genetic condition present from birth. A person is born with changes in both copies of the ACADVL gene, which affects the body’s ability to break down long-chain fatty acids for energy. However, symptoms can appear at different ages, and some individuals may not experience noticeable symptoms until later in childhood or adulthood.
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VLCAD deficiency is considered a rare disease. It is estimated to occur in approximately 1 in 30,000 to 1 in 100,000 births, though awareness and newborn screening have improved early diagnosis in recent years. In the United States, it is estimated that 2,000 to 3,5000 individuals live with a Long Chain Fatty Acid Oxidation Disorder
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Treatment typically includes a specialized diet of low fat, high carb foods and Medium Chain Triglycerides (MCT) supplementation , avoidance of fasting, and emergency care plans. Care is individualized and guided by a metabolic specialist and dietitian.
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Symptoms can vary widely but may include hypoglycemia (low blood sugar), muscle weakness, fatigue, exercise intolerance, rhabdomyolysis (muscle breakdown), and in some cases heart complications. Symptoms are often triggered during illness, fasting, or increased physical demand.
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Yes. VLCAD exists on a spectrum ranging from mild to more severe forms. Some individuals may experience frequent hospitalizations and medical complications, while others may have milder symptoms. Every child’s journey with VLCAD is unique.
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During fasting, the body relies more heavily on fat for energy. Because VLCAD affects fat metabolism, prolonged fasting can lead to rapid energy depletion, low blood sugar, and metabolic crisis. This is why frequent meals and snacks are often recommended.
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VLCAD is a complex medical condition that requires expert management. A metabolic geneticist and specialized care team help create individualized treatment plans, emergency protocols, and long-term monitoring strategies to support safety and quality of life.
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Yes. VLCAD deficiency is included in newborn screening programs in many countries, including the United States.
Newborn screening allows doctors to detect the condition before symptoms appear, enabling early monitoring and treatment.
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Yes, VLCAD deficiency can be detected before birth in some situations.
VLCAD deficiency is an inherited condition caused by changes in the ACADVL gene, and it follows an autosomal recessive inheritance pattern. This means that both parents are typically carriers of a single non-working copy of the gene.
If both parents are known carriers, or if there is a previously affected child in the family, prenatal genetic testing may be available. This can be performed through procedures such as:
Chorionic villus sampling (CVS), usually performed around 10–12 weeks of pregnancy
Amniocentesis, typically performed around 15–20 weeks of pregnancy
These tests analyze fetal DNA to determine whether the baby has inherited the gene changes associated with VLCAD deficiency.
Families who have a history of VLCAD deficiency may benefit from meeting with a genetic counselor or metabolic specialist before or during pregnancy to discuss testing options and reproductive planning.
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A carrier has one normal copy of the ACADVL gene and one altered copy. Carriers typically do not have symptoms because their body can still produce enough of the VLCAD enzyme for normal energy metabolism. However, carriers can pass the altered gene to their children.
If one child has VLCAD deficiency, will future children have it?
If both parents are carriers of an ACADVL mutation, each pregnancy has the same chance of inheritance:
25% chance the child will have VLCAD deficiency
50% chance the child will be a carrier
25% chance the child will inherit two working genes
These probabilities are the same for every pregnancy.
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Yes. Genetic testing can identify mutations in the ACADVL gene that cause VLCAD deficiency. Testing may be performed after a positive newborn screening result, when symptoms suggest a fatty acid oxidation disorder, or when family members want to know their carrier status.
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The outlook for children with VLCAD deficiency has improved significantly over the past two decades. Today, most children are diagnosed early through newborn screening and can begin treatment before serious complications occur. With appropriate management, many individuals with VLCAD grow up to attend school, participate in activities, and lead active lives.
Management typically includes avoiding prolonged fasting, maintaining regular nutrition, and following individualized dietary recommendations provided by a metabolic specialist and dietitian. Some individuals may require specialized medical foods or medications designed to help support energy production.
The long-term course can vary depending on the specific form of VLCAD deficiency and how well the condition is managed. Some individuals may experience episodes of low blood sugar, muscle pain, or fatigue during illness, prolonged exercise, or fasting. Regular follow-up with a metabolic care team helps families learn how to prevent and manage these situations safely.
As medical understanding and treatments continue to advance, the outlook for individuals living with VLCAD deficiency continues to improve.
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Yes. Different mutations in the ACADVL gene can affect how much VLCAD enzyme activity remains. Some mutations allow the enzyme to retain partial function, which may lead to milder symptoms, while others result in little or no enzyme activity and may cause more severe forms of the condition.
Should families consider genetic counseling?
Genetic counseling can help families understand:
inheritance patterns
carrier testing
genetic test results
family planning options
Genetic counselors specialize in helping families navigate genetic conditions like VLCAD deficiency.
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Still Have Questions?
VLCAD deficiency can be complex, and it’s normal to have questions about diagnosis, genetics, treatment, and daily management. Reach out to our team for support and trusted resources to help you better understand VLCAD and long-chain fatty acid oxidation disorders (LC-FAOD).
We’re committed to helping families, caregivers, and individuals affected by VLCAD find the information and support they need.
Please note: the information provided on this website is for educational purposes only. Any medical advice, diagnosis, or personalized treatment decisions should always be discussed with your metabolic specialist or healthcare team first.