Unexplained Tachypneoa and Severe Metabolic Acidosis in a Three-Month-Old Child: A Rare Presentation of Beta-Ketothiolose Deficiency.

Beta-ketothiolase (mitochondrial acetoacetyl-CoA thiolase, T2) deficiency is a rare inborn error of metabolism that is characterized by impaired metabolism of ketones and isoleucine. The condition is inherited as an autosomal recessive disorder. Herein, we present a child with T2 deficiency from Mahaoya, Eastern Province, Sri Lanka. This three-month-old child presented with fever, difficulty in breathing, and irritability for one day and was subsequently found to have severe metabolic acidosis with positive ketone bodies in urine. His blood glucose was normal. Metabolic screening showed increased urinary excretion of 2-methyl-3-hydroxybutyrate (2M3HB), 2-methyl acetoacetate (2MAA), and tiglylglycine (TIG). He was diagnosed to have beta-ketothiolase deficiency based on biochemical studies. Genetic studies were not done due to financial constraints in the family. Severe metabolic acidosis was successfully managed with intravenous sodium bicarbonate infusion. T2 deficiency would be a differential diagnosis in children with unsolved ketoacidosis. Children with T2 deficiency have a better outcome if detected and managed early. The reported patient had age-appropriate growth and development at the latest follow-up at three years eight months while he has been on oral carnitine and bicarbonate.