Beta-ketothiolase deficiency, or mitochondrial acetoacetyl-CoA thiolase (T2) deficiency, is a rare autosomal recessive disorder affecting isoleucine catabolism and ketone body metabolism. A patient from South India presented with acute ketoacidosis at 11 months of age. During the acute crisis the C5OH (2-methyl-3-hydroxybutyryl) carnitine and C5:1 (tiglyl) carnitine were elevated and large amounts of 2-methyl-3-hydroxybutyrate, tiglylglycine, and 2-methylacetoacetate were excreted. Brain CT showed bilateral basal ganglia lesions. Potassium ion-activated acetoacetyl-CoA thiolase activity was deficient in the patient's fibroblasts. The patient is a homozygote for a novel c.578T>G (M193R) mutation. This is the first report of T2 deficiency confirmed by enzyme and molecular analysis from India.
Keywords: 2-Methyl-3-hydroxybutyrate; ACAT1; C5OH; Ketoacidosis; T2 deficiency; Tiglylglycine.
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