Carnitine-acylcarnitine translocase (CACT) deficiency

About the condition CACT deficiency is a long-chain fatty acid oxidation disorder. It is a hereditary disease that is caused by a missing protein needed to convert fat into energy. It is a severe disorder associated with cardiomyopathy, arrhythmias, and liver disease and is invariably fatal in the first year of life.
Inheritance Autosomal recessive
Year screening started in WA 2005
Incidence in Australia Currently unknown
Gene defect Caused by defects in the SLC25A20 gene, which encodes a mitochondrial-membrane carrier protein that shuttles acylcarnitine substrates between the cytosol and the intramitochondrial matrix.
Symptoms if untreated
  • Hypoketotic hypoglycaemia
  • Hyperammonaemia
  • Cardiomyopathy, arrhythmia
  • Skeletal myopathy
  • Hepatomegaly
  • Coma and death
Metabolites on bloodspot screening
  • Increased long-chain acylcarnitines (C16 and C18:1)
  • Increased (C16+C18:1)/C2 ratio
Diagnostic tests
  • Plasma acylcarnitine profile
  • Urine organic acids
  • SLC25A20 gene analysis
Treatment
  • High-carbohydrate, low-fat diet
  • Restriction of long-chain fatty acids
  • Carnitine supplementation
  • Cornstarch supplementation
  • Avoidance of fasting
  • IV glucose during illness
Screening issues
  • Efficacy of treatment unknown; disease is usually fatal
  • Children with residual protein activity may have a better outcome