Carnitine-Acylcarnitine Translocase (CACT) Deficiency

Carnitine-acylcarnitine translocase (CACT) deficiency is a rare inherited disorder of fat breakdown (fatty-acid β-oxidation). The CACT protein sits in the inner wall of the mitochondria (the cell’s “power plant”) and shuttles long-chain fatty acids, attached to carnitine, into the mitochondrial matrix so they can be burned for energy. When CACT does not work, the body cannot use long-chain fats during stress or fasting. Energy falls, toxic by-products build up, and life-threatening illness can occur, often in newborns.

Carnitine-acylcarnitine translocase (CACT) deficiency is a rare, inherited disorder where the body cannot move long-chain fatty acids into the mitochondria—the cell’s “power stations”—to make energy, especially during fasting or illness. The problem comes from harmful changes in the SLC25A20 gene, which makes the CACT “shuttle” protein in the inner mitochondrial membrane. Without this shuttle, long-chain fats cannot be burned for fuel, so sugar (glucose) drops, harmful by-products build up, and the heart, liver, and muscles can be injured. Signs can start in the newborn period with sleepiness, poor feeding, low blood sugar without ketones, heart problems, and even sudden death, but milder and later-onset cases occur. Early diagnosis and careful day-to-day management greatly reduce risks. PMC+3NCBI+3Genetic Diseases Info Center+3

Most patients develop severe symptoms in the first hours to days of life: very low blood sugar without ketones (hypoketotic hypoglycemia), weak heart muscle or rhythm problems, breathing trouble, liver dysfunction, and brain symptoms like seizures. Some people present later in infancy or childhood with milder, stress-triggered episodes.

There is no cure yet. Care aims to keep the body out of “catabolic” states (when it would need to burn fat), prevent fasting, limit long-chain fat, and give safe energy sources (carbohydrates and certain medium/odd-chain fats). Emergency care during illness focuses on quick glucose support to stop fat breakdown, plus intensive monitoring. A newer FDA-approved odd-chain triglyceride, triheptanoin, can help some people with long-chain fatty-acid oxidation disorders (LC-FAODs), the group that includes CACT deficiency. PMC+2FDA Access Data+2

Other names

This condition is also called: CACT deficiency; SLC25A20 deficiency; carnitine/acylcarnitine translocase deficiency; mitochondrial carnitine-acylcarnitine carrier deficiency. All these names describe the same defect in the SLC25A20 gene which encodes the CACT protein.

Types

1. Severe neonatal-onset type. The most common form. Symptoms start within 24–72 hours after birth when milk feeds and short fasting begin. Babies can quickly develop hypoketotic hypoglycemia, arrhythmias, cardiomyopathy, liver failure, and encephalopathy. Mortality is high without rapid diagnosis and treatment. NCBI+1

2. Infantile-onset attenuated type. Some infants present after the newborn period with episodes during illness or fasting. Features may include lethargy, low blood sugar with few ketones, enlarged liver, and muscle weakness; heart involvement varies. NCBI

3. Childhood/late-onset episodic type. Rare. Children may have exercise- or illness-triggered rhabdomyolysis (muscle breakdown), weakness, or hypoglycemia, typically milder than neonatal disease but still risky during stress. NCBI

4. Maternal–fetal presentation. In some pregnancies carrying an affected fetus, the mother can develop liver complications similar to HELLP or acute fatty liver of pregnancy, because toxic fatty acids from the fetus cross into the mother’s circulation. This pattern is better documented in other long-chain oxidation disorders and has been reported with CACT deficiency. NCBI

Causes

The root cause is pathogenic variants in the SLC25A20 gene (one from each parent), giving autosomal recessive inheritance. Below are 20 practical “causes” and triggers that either cause the disease or cause decompensation in someone who has it:

1. Biallelic SLC25A20 variants. The essential genetic cause; variants reduce or abolish CACT function. NCBI

2. Consanguinity or shared ancestry. Raises the chance both parents carry the same rare variant. Orpha

3. Fasting (even a few hours in newborns). Without food, the body must burn fat; in CACT deficiency this fails, causing hypoketotic hypoglycemia. MedlinePlus+1

4. Intercurrent infection (fever, sepsis). Illness increases energy needs and triggers catabolism, precipitating crisis. NCBI

5. Cold exposure. Thermogenesis requires fat oxidation; failure worsens hypoglycemia and lethargy. NCBI

6. Prolonged exercise (older children). Uses fat for fuel and can provoke rhabdomyolysis or weakness. NCBI

7. High long-chain-fat meals without supervision. Overloads the impaired pathway. medlink.com

8. Low carbohydrate intake. Reduces glucose supply and forces fat burning, which is blocked. medlink.com

9. Delayed feeding in newborns. Common in the first day of life; can trigger the very first crisis. MedlinePlus

10. Undiagnosed newborn at home. Missed screening or discharge before results may allow an early crisis. babysfirsttest.org

11. Certain anesthetic/operative fasts. Pre-op fasting without glucose can precipitate decompensation. medlink.com

12. Valproate and some other drugs that increase energy demand or affect fatty-acid metabolism can worsen oxidation disorders; careful specialist oversight is needed. (General FAO disorder caution.) medlink.com

13. Dehydration. Worsens catabolism and toxin concentration. NCBI

14. Unrecognized heart stress. Arrhythmias increase metabolic demand and can spiral. NCBI

15. Interruption of prescribed MCT or glucose feeds. Removes metabolic “bridge” fuels. medlink.com

16. Carnitine depletion during illness. Low free carnitine may appear and complicate transport of residual substrate. (Management individualized.) NCBI

17. Coexisting metabolic stressors (e.g., another FAO disorder in family) can complicate recognition and care. Translational Pediatrics

18. Prematurity. Premature infants are more vulnerable to energy failure and complications. Thieme

19. Environmental heat with poor feeding. High demand plus low intake triggers catabolism. NCBI

20. Delayed emergency glucose during an episode. Prolongs hypoglycemia and organ stress. NCBI

Common symptoms and signs

1. Extreme sleepiness or lethargy. The brain lacks steady fuel when fat cannot be used; babies become floppy or difficult to arouse. MedlinePlus

2. Poor feeding and vomiting. Energy failure affects gut function and increases nausea, especially during illness. MedlinePlus

3. Breathing problems. Weak respiratory muscles and acidosis can cause rapid or labored breathing. MedlinePlus

4. Seizures. The brain is very sensitive to low glucose and toxins; seizures can appear early. MedlinePlus

5. Low blood sugar with few ketones. This “hypoketotic hypoglycemia” is a classic clue to long-chain FAO defects. MedlinePlus

6. Heart rhythm problems (arrhythmias). Accumulated long-chain acylcarnitines and energy failure irritate the heart. NCBI

7. Weak heart (cardiomyopathy). The heart relies on fat; impaired oxidation can weaken muscle and enlarge the heart. Orpha

8. Enlarged liver (hepatomegaly). Fat builds up and the liver struggles to keep glucose normal. MedlinePlus

9. High ammonia (hyperammonemia). The stressed liver cannot clear ammonia well during crisis. Baby Detect

10. Muscle weakness or floppiness. Skeletal muscle cannot generate energy from fat during stress. Orpha

11. Rhabdomyolysis in older children. Exercise or fever can lead to muscle breakdown, pain, and dark urine. NCBI

12. Failure to thrive or poor weight gain. Repeated crises, low energy, and feeding issues slow growth. NCBI

13. Irritability or coma in severe episodes. Brain energy failure ranges from fussiness to coma. MedlinePlus

14. Sudden clinical collapse in neonates. Rapid progression is possible without prompt glucose and specialty care. Orpha

15. Temperature instability. Trouble maintaining warmth reflects impaired fat-fuel thermogenesis. NCBI

Diagnostic tests

A) Physical examination (bedside assessment)

1. General status and hydration. Check alertness, tone, hydration, and signs of shock; infants with CACT deficiency can deteriorate quickly during fasting or illness. NCBI

2. Growth and head circumference. Repeated crises can affect growth; measurement helps track recovery and nutrition. NCBI

3. Liver size and tenderness. Palpating the abdomen for hepatomegaly supports a fatty-acid oxidation disorder during crisis. MedlinePlus

4. Cardiac exam. Heart rate, rhythm, gallops, and signs of heart failure can point to cardiomyopathy or arrhythmia. Orpha

5. Neurologic screen. Tone, reflexes, seizure activity, and level of consciousness guide urgency and glucose targets. MedlinePlus

B) Manual/bedside functional checks

6. Point-of-care glucose with ketones. Low glucose with low/absent blood or urine ketones is a red flag for long-chain FAO defects like CACT deficiency. MedlinePlus

7. Capillary refill and perfusion. Poor perfusion suggests shock or heart dysfunction requiring immediate dextrose infusion. NCBI

8. Muscle strength and pain assessment. Tender muscles or weakness, especially after fever/exertion, suggests rhabdomyolysis risk. NCBI

C) Laboratory and pathological tests

9. Comprehensive metabolic panel. Looks for hypoglycemia, metabolic acidosis, elevated liver enzymes, and electrolyte shifts during crisis. NCBI

10. Plasma acylcarnitine profile by tandem mass spectrometry. The key screen: high long-chain acylcarnitines—especially C16 and C18:1—suggest CACT deficiency (also seen in CPT2 deficiency; ratios and genetics separate them). babysfirsttest.org+1

11. Free and total carnitine. Free carnitine can be low in crises, and total patterns help interpretation with the acylcarnitine profile. NCBI

12. Urine organic acids. Abnormal dicarboxylic acids and related patterns support a long-chain oxidation block. HKMJ

13. Plasma ammonia. Hyperammonemia is common in severe episodes and needs urgent treatment. Baby Detect

14. Creatine kinase (CK) and myoglobin. Elevation shows muscle breakdown during rhabdomyolysis. NCBI

15. Lactate and blood gas. Elevated lactate and metabolic acidosis reflect energy failure. NCBI

16. Newborn screening (heel-prick). Many programs flag CACT deficiency from acylcarnitine patterns (e.g., C16/C18:1); positive screens need urgent confirmatory testing. newbornscreening.hrsa.gov+1

17. Molecular genetic testing of SLC25A20. Confirms diagnosis; methods include sequencing and deletion/duplication analysis. Family testing supports carrier detection and future planning. NCBI+1

D) Electrodiagnostic tests

18. 12-lead ECG and rhythm monitoring. Detects arrhythmias, conduction blocks, or ischemic-like changes caused by toxic acylcarnitines and energy failure. NCBI

19. Echocardiography. Evaluates cardiomyopathy (dilated or hypertrophic features), wall motion, and function during and after crises. Orpha

20. EEG (if seizures). Assesses seizure burden and guides anticonvulsant selection while glucose is stabilized. MedlinePlus

(Additional imaging such as liver ultrasound for fatty change or brain MRI after severe episodes may help assess complications, though they are supportive rather than diagnostic of CACT deficiency.) Orpha

Non-pharmacological treatments (therapies & other strategies)

1. Strict avoidance of fasting (day and night)
   Description: Plan regular meals and snacks so the body never needs to burn long-chain fat for energy. Babies and some children may need overnight feeds or uncooked cornstarch at bedtime under specialist guidance. Purpose: Prevent catabolism that can trigger hypoglycemia, heart stress, and rhabdomyolysis. Mechanism: Continuous carbohydrate intake provides glucose, raises insulin, and suppresses lipolysis, reducing long-chain fatty acid flux that CACT cannot transport. FAOD In Focus logo+1

2. High-carbohydrate, low long-chain-fat diet
   Description: Daily diet emphasizes complex carbs, lean protein as advised, and restricts long-chain fats; essential fats are still included in safe amounts. Purpose: Reduce reliance on long-chain fat oxidation and stabilize energy. Mechanism: Carbohydrates become the main fuel; limited LC-fat lowers production of long-chain acylcarnitines that accumulate when CACT is defective. PMC+1

3. Medium-chain triglyceride (MCT)–based nutrition (dietary medical food)
   Description: Under a metabolic dietitian’s plan, use MCT oil or MCT-containing formulas because medium-chain fatty acids can enter mitochondria without the carnitine shuttle. Purpose: Provide safe calories and fat without stressing the defective transport step. Mechanism: Medium-chain fats bypass the CACT step and are oxidized more directly. (Note: MCT oil is a medical food, not an FDA-approved drug.) PMC

4. Emergency “sick-day” plan at home
   Description: Families keep written instructions: more frequent carbs, glucose polymer drinks, and clear criteria for going to hospital. Purpose: Shorten time to treatment when appetite is low, vomiting occurs, or fever rises. Mechanism: Extra glucose (oral if possible) and lower activity prevent a catabolic swing before IV therapy is needed. ResearchGate

5. Hospital emergency protocol for decompensation
   Description: In ED/ICU, start IV dextrose early (typically 10% glucose or higher) with monitoring and team consultation. Purpose: Immediately stop fat mobilization and protect brain, heart, and liver. Mechanism: High-rate glucose infusion raises insulin and suppresses lipolysis, decreasing long-chain fatty acid release. newenglandconsortium.org+1

6. Peri-operative carbohydrate support
   Description: Before anesthesia, start IV glucose; avoid prolonged pre-op fasting; resume feeding early post-op. Purpose: Prevent intraoperative catabolism and cardiac/rhabdomyolysis events. Mechanism: Exogenous glucose limits fat use during surgical stress. pedworld.ch

7. Cardiac surveillance and early intervention
   Description: Routine ECG/echo to detect cardiomyopathy or arrhythmias; consult cardiology for management (beta-blockers, devices if indicated). Purpose: Reduce risk of sudden decompensation. Mechanism: Early detection and standard cardiology care mitigate LC-acylcarnitine-related cardiac stress. NCBI

8. Temperature and infection control
   Description: Treat fever early, maintain hydration, and lower exertion during illness. Purpose: Fever and infection increase energy demand and lipolysis. Mechanism: Reducing metabolic stress reduces fat mobilization and crisis risk. Çocuk Metabolizma

9. Avoid drugs that increase lipolysis or worsen FAO
   Description: Avoid or cover with glucose drugs like epinephrine that can raise lipolysis; avoid valproate in FAO disorders. Purpose: Prevent medication-triggered crises. Mechanism: Minimizing adrenergic or mitochondrial stressors keeps fat release down. newenglandconsortium.org+1

10. School/work care plans and medical alert ID
    Description: Written plans for snacks, activity, and emergency steps; wear a medical ID bracelet. Purpose: Speed correct action if symptoms arise away from home. Mechanism: Early carbs and triage reduce catabolic time. BIMDG

11. Exercise pacing and recovery nutrition
    Description: Moderate, supervised activity with pre-/post-carb intake; avoid prolonged, intense exertion without fueling. Purpose: Prevent exercise-triggered rhabdomyolysis. Mechanism: Glucose availability and insulin suppress lipolysis during/after activity. PMC

12. Night-time feeding strategies
    Description: Overnight tube feeds or cornstarch as prescribed to avoid long fasts. Purpose: Prevent early-morning hypoglycemia. Mechanism: Slow-release carbohydrate maintains glucose and insulin overnight. FAOD In Focus logo

13. Specialist dietitian follow-up
    Description: Routine review of growth, dietary tolerance, essential fat intake (e.g., DHA), and vitamins. Purpose: Balance safety with adequate nutrition. Mechanism: Adjust macronutrients and essential fatty acids to individual response. PMC

14. Newborn screening follow-through and family testing
    Description: Confirm positive screens, test siblings, and consider carrier testing. Purpose: Early diagnosis prevents crises. Mechanism: Genetic confirmation guides targeted prevention from day one. Europe PMC

15. Pregnancy and delivery planning
    Description: High-risk obstetric and metabolic team plan for maternal illness risk and baby monitoring. Purpose: Reduce neonatal decompensation and maternal complications linked to fetal LC-FAOD. Mechanism: Proactive glucose support and rapid newborn evaluation. Worcestershire Acute Hospitals NHS Trust

16. Written emergency letter
    Description: Carry a one-page letter for ED staff with exact fluids and monitoring advice. Purpose: Cuts delays and errors. Mechanism: Standardized, pre-agreed steps start quickly in any hospital. Metabolic

17. Rhabdomyolysis monitoring and fluid protocols
    Description: If muscle pain or dark urine, check CK, electrolytes, start aggressive fluids, and monitor kidneys. Purpose: Prevent renal damage. Mechanism: Volume resuscitation dilutes myoglobin and supports perfusion. Medscape+1

18. Vaccination per schedule
    Description: Keep routine vaccines up to date to lower infection risk. Purpose: Fewer infections = fewer catabolic illnesses. Mechanism: Immune prevention reduces lipolysis-triggering fevers. MDPI

19. Education in early symptom recognition
    Description: Teach families to spot lethargy, vomiting, poor feeding, and muscle pain early. Purpose: Shorten time to carbohydrate rescue. Mechanism: Early glucose prevents fat catabolism escalation. ResearchGate

20. Access to experienced metabolic center
    Description: Build care with a center familiar with LC-FAOD/CACT. Purpose: Optimize diet, monitoring, and emerging therapies. Mechanism: Specialist protocols improve outcomes in rare disorders. newenglandconsortium.org

Drug treatments

Important note: For CACT deficiency, only a few drug products have strong, condition-relevant evidence or FDA labeling helpful to management. There is no curative drug; treatment focuses on glucose support, suppressing lipolysis, and providing safe calories. Below are the most important, evidence-based medications/products, with FDA labeling where applicable. (Because many supportive measures are not “drugs,” it’s not scientifically correct to list 20 discrete, FDA-labeled CACT medications.)

1. Dextrose injection (IV glucose, various strengths, e.g., 10%)
   Class: Parenteral carbohydrate/caloric source. Dosage/Time: Titrated in hospital to maintain euglycemia; started promptly in decompensation. Purpose: Immediate energy to stop fat breakdown during illness/surgery. Mechanism: Raises insulin, suppresses lipolysis, prevents hypoketotic hypoglycemia. Key side effects: Fluid/electrolyte imbalance if mismanaged; monitor carefully. FDA Access Data+2FDA Access Data+2

2. Regular insulin (IV/SC in ICU protocols when needed)
   Class: Short-acting insulin. Dosage/Time: In selected crises with high lipolysis or hyperglycemia, continuous IV insulin (ICU protocol) alongside dextrose; specialist-directed. Purpose: Further suppress adipose lipolysis when glucose alone is insufficient. Mechanism: Insulin physiologically shuts down fat release, reducing long-chain fatty acid flux the CACT system can’t handle. Side effects: Hypoglycemia, hypokalemia; requires close monitoring. FDA Access Data+1

3. Triheptanoin (DOJOLVI®)
   Class: Odd-chain medium-chain triglyceride (Rx). Dosage/Time: Oral, dose individualized (label starts at total daily 1–3 g/kg/day divided with meals). Purpose: Source of safe calories/fat and anaplerotic substrates (propionyl-CoA) to refill the Krebs cycle. Mechanism: Bypasses carnitine shuttle; heptanoate yields intermediates that support energy generation even when β-oxidation of LC-fats is blocked. Side effects: GI symptoms; caution with mixing and administration per label. Evidence: FDA-approved for long-chain FAODs (group that includes CACT). FDA Access Data+1

4. Levocarnitine (CARNITOR®) — conditional use only
   Class: Carnitine supplement (Rx). Dosage/Time: Oral or IV per label for secondary carnitine deficiency; only if free carnitine is low and under metabolic specialist guidance. Purpose: Replenish free carnitine to carry acyl groups; however, in long-chain FAODs it can raise long-chain acylcarnitines; practice varies. Mechanism: Restores carnitine pools; may aid in removing acyl groups, but can increase potentially toxic LC-acylcarnitines. Side effects: GI upset, fishy odor; monitor acylcarnitines. FDA Access Data+2managementguidelines.net+2

5. Parenteral nutrition components when enteral intake fails
   Class: Hospital-grade nutrition (glucose; amino acids; lipids if/when safe). Dosage/Time: ICU-directed; glucose first; long-chain lipids minimized or avoided; MCT-containing options considered cautiously with specialist input. Purpose: Maintain anabolism when oral/enteral intake is not possible. Mechanism: Intravenous glucose eliminates need to burn fat. Side effects: Line infections, electrolyte shifts; careful monitoring required. FDA Access Data

6. Electrolyte/acid–base adjuncts in rhabdomyolysis (case-by-case)
   Class: IV fluids ± bicarbonate strategies per general rhabdomyolysis care. Dosage/Time: ICU protocols only. Purpose: Protect kidneys and correct metabolic derangements during severe muscle breakdown episodes. Mechanism: Volume and pH management lower myoglobin nephrotoxicity. Side effects: Fluid overload; alkalosis; must be individualized. Medscape+1

Why not list more “drugs”? Because beyond glucose/insulin for catabolic crises and triheptanoin for LC-FAOD, there are no additional FDA-labeled medications specifically proven to treat CACT deficiency. Some off-label or investigational approaches exist (e.g., fibrates, antioxidants), but high-quality evidence in CACT is limited or conflicting; routinely listing them as “key drugs” would be misleading. PMC

Dietary molecular supplements

Important note: These are dietary or medical-food adjuncts, not cures. Always use with a metabolic team.

1. Medium-chain triglyceride oil (medical food) — Provides safe calories that bypass carnitine shuttle; dose individualized by dietitian; mechanism: direct mitochondrial uptake/oxidation. Evidence base in LC-FAOD nutrition guidelines. PMC

2. Docosahexaenoic acid (DHA) — Supports neural/retinal health when long-chain fats are restricted; typical doses per age/weight; mechanism: essential fatty acid support. PMC

3. Essential fatty acid balance (linoleic/ALA as required) — Prevents deficiency due to LC-fat restriction; dietitian sets minimal safe amounts; mechanism: membrane and eicosanoid functions. PMC

4. Uncooked cornstarch (night-time) — Slow-release starch to maintain glucose overnight; dose by weight; mechanism: steady glucose to prevent nocturnal lipolysis. FAOD In Focus logo

5. Standard pediatric/adult multivitamin — Covers micronutrient gaps on restricted diets; mechanism: prevents vitamin deficiencies that can worsen energy metabolism. MDPI

6. Electrolyte-glucose oral solutions during illness — Provide carbs and fluids when intake is poor; mechanism: maintain euglycemia/anabolism. ResearchGate

7. Protein adjusted to needs — Ensures growth/recovery without excessive catabolic load; mechanism: supports lean mass and immune function. MDPI

8. Omega-3 (EPA/DHA) balance — May help inflammation and cardiac health; dosing per age; mechanism: membrane effects; (evidence growing in FAOD nutrition practice). PMC

9. Glucose polymer drinks (maltodextrin-based) — Higher-calorie carb for sport/illness; mechanism: quick insulin-mediated lipolysis suppression. ResearchGate

10. Calcium/Vitamin D as indicated — Bone health support if diet limited; mechanism: prevents deficiency related to restricted diets/low activity. MDPI

Immunity-booster / regenerative / stem-cell drugs

There are no evidence-based “immunity booster,” regenerative, or stem-cell drugs for CACT deficiency. Using unproven products risks harm and delays proven care (glucose support, diet, triheptanoin). If you want a paragraph section here, the only responsible content is: avoid unproven therapies and enroll in research through a metabolic center when available. MDPI

Procedures/surgeries

1. Gastrostomy tube (G-tube) placement
   For children who can’t maintain overnight or illness-day intake orally; improves adherence to continuous feeds and reduces fasting. Not curative; supports stable glucose and prevents catabolism. newenglandconsortium.org

2. Implantable cardioverter-defibrillator (ICD) or pacemaker in selected patients
   If serious arrhythmias or conduction problems occur despite metabolic stabilization, cardiology may place devices. Aim is preventing sudden death from malignant rhythms. NCBI

3. Central venous access (port/PICC) for recurrent crises
   Facilitates rapid IV dextrose and labs during frequent decompensations; reduces delays in emergency carbohydrate support. BIMDG

4. Heart transplantation (exceptional cases)
   Considered only for end-stage cardiomyopathy unresponsive to medical/metabolic therapy; case-by-case in specialized centers. PMC

5. Liver transplantation (experimental/rare)
   Very limited data in LC-FAOD; not standard for CACT. Potential risks may outweigh uncertain benefit; must be individualized and typically not advised. PMC

Prevention

1. Never fast; plan snacks and overnight carbs. FAOD In Focus logo

2. Follow a high-carb, low LC-fat meal plan tailored by a metabolic dietitian. PMC

3. Keep a home sick-day plan and go early to hospital if vomiting/poor intake. ResearchGate

4. Carry an emergency letter everywhere. Metabolic

5. Pre-op plans for any procedure; insist on IV glucose coverage. pedworld.ch

6. Avoid drugs that increase lipolysis or harm mitochondria (e.g., epinephrine without glucose cover; valproate). newenglandconsortium.org+1

7. Hydrate well during illness and after exertion. ResearchGate

8. Keep vaccinations up to date. MDPI

9. Educate caregivers/teachers; wear a medical ID. BIMDG

10. Maintain regular specialist follow-up and monitoring. newenglandconsortium.org

When to see a doctor (or go to the ER)

Seek urgent care now for: persistent vomiting, refusal to feed, extreme sleepiness, seizures, fainting/irregular heartbeat, chest pain, muscle pain with dark urine, fever that reduces intake, or any illness where the child can’t keep carbohydrates down. In the hospital, early IV dextrose and monitoring are crucial—do not wait for blood sugar to fall before starting glucose in known LC-FAOD. BIMDG+1

What to eat and what to avoid

Eat more of: complex carbohydrates (rice, bread, pasta, potatoes, fruits, vegetables), lean proteins as advised, measured essential fats and DHA, and MCT-containing medical foods per plan. Why: these supply safe energy that reduces fat breakdown. PMC

Avoid or limit: long fasts; high-fat meals rich in long-chain fats; ketogenic diets; strenuous prolonged exercise without fueling; and drugs that raise lipolysis or stress mitochondria (coordinate with your team). Why: these increase long-chain fatty acid use that CACT cannot process. newenglandconsortium.org+1

Frequently Asked Questions (FAQs)

1. Is CACT deficiency the same as CPT-2 deficiency?
   No. Both are long-chain fatty-acid oxidation disorders, but CACT affects the transporter (SLC25A20) that moves acylcarnitines across the inner mitochondrial membrane, while CPT-2 is a different enzyme defect. NCBI

2. Why is fasting dangerous?
   Fasting forces the body to burn fat. In CACT deficiency, that pathway is blocked, so harmful intermediates build up and glucose drops, risking heart/muscle injury and brain symptoms. PMC

3. What does an ED need to do first?
   Start IV dextrose promptly to stop lipolysis, contact the metabolic team, and monitor glucose/electrolytes/CK. BIMDG+1

4. Is carnitine good or bad?
   It depends. If free carnitine is low, specialists may give levocarnitine; but in long-chain FAODs, extra carnitine can raise long-chain acylcarnitines. Practice varies worldwide; monitoring is essential. managementguidelines.net+1

5. What is triheptanoin and who benefits?
   An FDA-approved prescription oil for LC-FAOD. It can improve energy and reduce events in some patients by providing anaplerotic substrates; dosing and mixing follow the label. FDA Access Data

6. Can I exercise?
   Yes—with planning. Fuel before/during/after, avoid prolonged intense sessions without carbs, and stop if muscle pain or dark urine appears. PMC

7. Are there gene therapies?
   Not yet for CACT deficiency. Research is ongoing in FAODs, but nothing approved for SLC25A20 today. MDPI

8. Why is DHA mentioned if we limit fats?
   DHA is an essential long-chain fat needed in small, supervised amounts for brain and eye health; dietitians ensure enough without triggering crises. PMC

9. Could arrhythmias or cardiomyopathy improve?
   Yes—stabilization with proper diet, glucose support during illnesses, and, in some cases, triheptanoin may help cardiac function; cardiology follow-up is vital. NCBI

10. What medications should I be careful with?
    Those that stimulate lipolysis (e.g., epinephrine without glucose cover) or harm mitochondria (e.g., valproate in FAO disorders) require caution or avoidance; always consult your metabolic team. newenglandconsortium.org+1

11. How are newborns diagnosed?
    By acylcarnitine profiling and confirmed by SLC25A20 genetic testing; early diagnosis improves outcomes. Europe PMC

12. Why do we focus so much on glucose?
    Glucose raises insulin, which switches the body away from fat use—exactly what CACT deficiency needs during stress. PMC

13. What if my child can’t keep food down?
    Go to the hospital for IV dextrose immediately—do not wait for a low glucometer reading if your child has CACT and is not taking carbohydrates. BIMDG

14. Can adults have CACT deficiency?
    Yes, milder or later-onset cases exist. The same principles—avoid fasting, plan exercise fueling, and follow sick-day rules—apply. NCBI

15. Where can clinicians find protocols?
    GeneReviews, New England Consortium, BIMDG emergency materials, and recent FAOD reviews offer pragmatic, specialist-oriented guidance. PMC+3NCBI+3newenglandconsortium.org+3

Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical  history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.

The article is written by Team RxHarun and reviewed by the Rx Editorial Board Members

Last Updated: November 12, 2025.

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