Very Long-Chain Acyl-CoA Dehydrogenase (VLCAD) Deficiency
A rare inherited fatty acid oxidation disorder that prevents the body from properly breaking down long-chain fats for energy, with presentations ranging from severe neonatal cardiomyopathy to adult-onset muscle disease.
- Newborn screening detectable
- Lifelong dietary management
- Specialist metabolic care available
- Inheritance Pattern
- Autosomal Recessive
- Gene Involved
- ACADVL
- Detected By
- Newborn Screening (Acylcarnitine Profile)
- Key Therapy
- Dietary Management, Triheptanoin
Condition Overview
Very Long-Chain Acyl-CoA Dehydrogenase (VLCAD) Deficiency is an inherited disorder of fatty acid oxidation. The VLCAD enzyme, encoded by the ACADVL gene, is normally responsible for the first step in breaking down long-chain fatty acids inside mitochondria so the body can use fat as a fuel source, particularly during fasting, illness, or prolonged exercise.
When VLCAD activity is reduced or absent, the body cannot efficiently convert long-chain fats into energy. This can lead to dangerously low blood sugar (hypoglycemia), heart muscle dysfunction, liver enlargement, and muscle breakdown, especially when energy demands rise and glucose stores run low.
VLCAD deficiency is now identified through expanded newborn screening in many countries, allowing many affected infants to be diagnosed and started on preventive management before a life-threatening metabolic crisis occurs. Early and accurate diagnosis, paired with lifelong dietary and emergency planning, meaningfully changes outcomes.
Types and Subtypes
VLCAD deficiency is generally classified by age of onset and the organ systems primarily affected, which broadly correlates with how much residual enzyme activity remains.
Symptoms and Signs
Symptoms vary widely depending on subtype but share an underlying theme: problems arise when the body needs to rely on fat for fuel, such as during fasting, illness, or strenuous exercise.
Causes and Risk Factors
VLCAD deficiency is caused by inherited changes in the ACADVL gene rather than by lifestyle or environmental exposures.
Diagnosis and Investigations
Diagnosis combines biochemical screening, confirmatory metabolic testing, and genetic analysis.
Disease Severity and Risk Stratification
VLCAD deficiency is not staged like a cancer; instead, individuals are stratified by phenotype severity, which guides the intensity of dietary and monitoring recommendations.
Standard Treatment Options
Management centers on avoiding fasting, optimizing dietary fat sources, and having an emergency plan for illness.
Advanced and Emerging Therapies
Beyond dietary management, a specific medical food therapy and ongoing research are changing the treatment landscape for fatty acid oxidation disorders.
Medical Food / Anaplerotic Therapy
Triheptanoin (UX007)
An odd-chain triglyceride approved as a source of fat calories and anaplerotic substrate for long-chain fatty acid oxidation disorders, used to help reduce major clinical events such as hypoglycemia and cardiomyopathy.
Nutritional Support
Medium-Chain Triglyceride (MCT) Supplementation
Provides a fat source that bypasses the VLCAD enzyme step, supporting energy needs while limiting accumulation of toxic long-chain fat intermediates.
Research Direction
Gene and Enzyme-Targeted Approaches
Early-stage research is exploring gene therapy and chaperone-based strategies for fatty acid oxidation disorders, though these remain investigational.
Biomarkers and Precision Medicine
Biochemical and genetic markers guide diagnosis, severity assessment, and ongoing monitoring.
When a Second Opinion May Be Important
Because VLCAD deficiency is rare, access to a metabolic specialist with direct experience in fatty acid oxidation disorders can meaningfully change day-to-day management.
Clinical Trials and Research
Prognosis and Key Outcome Factors
Outcomes in VLCAD deficiency vary substantially by phenotype and how early management begins. Identification through newborn screening, before a metabolic crisis occurs, is associated with better long-term outcomes for many patients.
Supportive Care and Living with VLCAD Deficiency
Day-to-day life with VLCAD deficiency involves practical planning around meals, illness, and activity, alongside emotional support for the whole family.
How CancerFax Helps You Explore Treatment Options
CancerFax helps families affected by VLCAD deficiency get specialist medical report review, coordinate second opinions with metabolic genetics centers, and access information on advanced therapies such as triheptanoin.
Get a free case reviewFrequently Asked Questions
VLCAD deficiency is an inherited disorder in which the body cannot efficiently break down long-chain fats for energy, due to reduced activity of the VLCAD enzyme encoded by the ACADVL gene.
It is most often detected through expanded newborn screening using an acylcarnitine profile, followed by confirmatory genetic and metabolic testing.
Yes, it follows an autosomal recessive inheritance pattern, meaning a child must inherit an altered ACADVL gene copy from each parent.
Prolonged fasting, illness, fever, and intense or prolonged exercise are common triggers because they increase reliance on fat for energy.
Avoiding prolonged fasting and replacing some long-chain dietary fat with medium-chain triglyceride (MCT) oil are central strategies, individualized by a metabolic dietitian.
Triheptanoin is an approved medical food that provides an alternative fat source and anaplerotic substrate, used to help reduce major clinical events in long-chain fatty acid oxidation disorders.
Yes, particularly the severe neonatal-onset form, which can cause cardiomyopathy and arrhythmia requiring close cardiology monitoring.
Yes, a later-onset myopathic form can present in adolescence or adulthood with exercise intolerance and recurrent muscle breakdown rather than infancy-onset symptoms.
Regular metabolic specialist follow-up, periodic echocardiograms, and creatine kinase checks are commonly recommended depending on phenotype.
Yes. CancerFax can help families obtain medical report review, coordinate second opinions with metabolic genetics specialists, and navigate access to advanced therapies such as triheptanoin and specialist center referrals.