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GTR Home > Conditions/Phenotypes > Carnitine acylcarnitine translocase deficiency


Excerpted from the GeneReview: Carnitine-Acylcarnitine Translocase Deficiency
Carnitine-acylcarnitine translocase (CACT) is a critical component of the carnitine shuttle, which facilitates the transfer of long-chain fatty acylcarnitines across the inner mitochondrial membrane. CACT deficiency causes a defect in mitochondrial long-chain fatty acid β-oxidation, with variable clinical severity. Severe neonatal-onset disease is most common, with symptoms evident within two days after birth; attenuated cases may present in the first months of life. Hyperammonemia and cardiac arrhythmia are prominent in early-onset disease, with high rates of cardiac arrest. Other clinical features are typical for disorders of long-chain fatty acid oxidation: poor feeding, lethargy, hypoketotic hypoglycemia, hypotonia, transaminitis, liver dysfunction with hepatomegaly, and rhabdomyolysis. Univentricular or biventricular hypertrophic cardiomyopathy, ranging from mild to severe, may respond to appropriate dietary and medical therapies. Hyperammonemia is difficult to treat and is an important determinant of long-term neurocognitive outcome. Affected individuals with early-onset disease typically experience brain injury at presentation, and have recurrent hyperammonemia leading to developmental delay / intellectual disability. Affected individuals with later-onset disease have milder symptoms and are less likely to experience recurrent hyperammonemia, allowing a better developmental outcome. Prompt treatment of the presenting episode to prevent hypoglycemic, hypoxic, or hyperammonemic brain injury may allow normal growth and development.

Genes See tests for all associated and related genes

  • Also known as: CAC, CACT, SLC25A20
    Summary: solute carrier family 25 member 20

Clinical features


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Practice guidelines

  • ACMG Algorithm, 2022
    American College of Medical Genetics and Genomics, Algorithm, C16 +/- C18:1 Elevated: CPT II or CACT, 2022
  • ACMG ACT, 2022
    American College of Medical Genetics and Genomics, Newborn Screening ACT Sheet, Increased C16 and/or C18:1 Acylcarnitine, Carnitine Palmitoyltransferase II (CPT II) Deficiency and Carnitine Acylcarnitine Translocase (CACT) Deficiency, 2022

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