Beta-ketothiolase (BKT) deficiency

Alternative names
  • alpha-methylacetoacetic aciduria
  • 3-ketothiolase deficiency
  • Mitochondrial acetoacetyl-CoA thiolase deficiency
  • T2 deficiency
  • 3-oxothiolase deficiency
  • 2-methyl-3-hydroxybutyric acidaemia
About the condition BKT deficiency is an organic acid disorder. It is a hereditary disease that is caused by a missing enzyme needed to convert protein into energy. There is also failure to utilise ketone bodies.
Inheritance Autosomal recessive
Year screening started in WA
2005 
Incidence in Australia Currently unknown
Enzyme defect Deficiency of 3-ketothiolase, which converts 2-methylacetoacetyl-CoA to propionyl-CoA and acetyl-CoA.
Symptoms if untreated
  • Episodic ketoacidosis
  • Nausea and vomiting
  • Intellectual disability
  • Coma and death possible
  • Significant clinical heterogeneity
Metabolites on bloodspot screening Increased 2-methyl-3-hydroxybutyrylcarnitine and tiglylcarnitine (C5OH and C5:1).
Diagnostic tests
  • Plasma acylcarnitine profile
  • Urine organic acids
  • ACAT1 gene analysis
Treatment
  • Low-protein diet
  • Carnitine supplementation
  • Avoidance of fasting
  • IV glucose and bicarbonate during crisis episodes
Screening issues Not all cases will show biochemical abnormalities on newborn screening.