Summary about Disease
Carnitine-acylcarnitine translocase (CACT) deficiency is a rare inherited metabolic disorder that prevents the body from properly using fats for energy. This deficiency affects the transport of long-chain fatty acids into the mitochondria, the energy-producing centers of cells. Without proper transport, fatty acids cannot be broken down to produce energy, leading to energy depletion, particularly during periods of fasting or illness. This can result in serious complications affecting the heart, liver, and muscles.
Symptoms
Symptoms can vary depending on the severity of the deficiency. Severe (neonatal onset) symptoms include:
Hypoketotic hypoglycemia (low blood sugar without ketones)
Cardiac arrest
Muscle weakness (hypotonia)
Enlarged heart (cardiomyopathy)
Liver problems
Breathing difficulties
Seizures
Irritability Less severe (late-onset) symptoms may include:
Muscle pain and weakness with exercise or illness
Episodes of low blood sugar
Rhabdomyolysis (muscle breakdown)
Causes
CACT deficiency is caused by mutations in the SLC25A20 gene. This gene provides instructions for making the carnitine-acylcarnitine translocase enzyme. Mutations in this gene lead to a non-functional or deficient enzyme, preventing the transport of fatty acids across the mitochondrial membrane. It is inherited in an autosomal recessive pattern, meaning that both parents must carry a copy of the mutated gene for a child to be affected.
Medicine Used
4. Medicine used There is no specific "cure" for CACT deficiency, but management strategies can help control symptoms. These may include:
Frequent feeding: Avoiding long periods without food to prevent hypoglycemia.
Low-fat, high-carbohydrate diet: Reducing the reliance on fat for energy and increasing carbohydrate intake.
Carnitine supplementation: Although the enzyme itself is deficient, carnitine can help in some cases by facilitating the removal of accumulated acylcarnitines.
Medium-chain triglyceride (MCT) oil: Can be used as a supplemental energy source, as MCTs can enter the mitochondria without CACT.
Emergency protocols: Parents and caregivers should be trained to recognize symptoms of metabolic crisis and administer glucose or seek immediate medical attention.
Is Communicable
No, CACT deficiency is not communicable. It is a genetic disorder caused by mutations in the SLC25A20 gene and cannot be spread from person to person.
Precautions
Strict adherence to dietary recommendations: Maintaining a low-fat, high-carbohydrate diet and frequent feeding schedule is crucial.
Avoidance of prolonged fasting: Especially during illness or exercise.
Prompt treatment of illnesses: Even minor illnesses can trigger a metabolic crisis.
Monitoring blood glucose levels: Regular monitoring can help prevent hypoglycemia.
Emergency plan: Having a written emergency plan and readily available glucose source.
Genetic counseling: For families with a history of CACT deficiency, genetic counseling can help assess the risk of having another affected child.
How long does an outbreak last?
CACT deficiency is not an outbreak. A metabolic crisis or episode can last from a few hours to several days depending on the severity and how quickly it is treated.
How is it diagnosed?
Diagnosis typically involves:
Newborn screening: Many states include CACT deficiency in their newborn screening programs, which involves analyzing a blood sample for abnormal levels of acylcarnitines.
Blood tests: Measuring acylcarnitine levels in the blood can help identify the deficiency.
Urine organic acid analysis: Helps identify abnormal metabolites.
Fibroblast assay: Measurement of CACT enzyme activity in cultured skin fibroblasts.
Genetic testing: Confirming the diagnosis by identifying mutations in the SLC25A20 gene.
Timeline of Symptoms
9. Timeline of symptoms
Severe (Neonatal Onset): Symptoms often appear within the first few days or weeks of life.
Less Severe (Late-Onset): Symptoms can appear during infancy, childhood, or even adulthood, often triggered by fasting, illness, or exercise. The onset can be variable.
Important Considerations
Early diagnosis is crucial: Prompt diagnosis and management can significantly improve outcomes and prevent severe complications.
Lifelong management: CACT deficiency requires lifelong adherence to dietary and medical recommendations.
Family support: Support groups and resources for families affected by CACT deficiency can be valuable.
Individualized treatment: Management strategies should be tailored to the individual's specific needs and symptoms.
Coordination of care: Requires a multidisciplinary team including a metabolic specialist, dietitian, and other healthcare professionals.