Beta-Ketothiolase Deficiency Initial Diagnosis in a 7-Year-Old Boy– A Case Report

Background: Beta-ketothiolase deficiency is a rare inherited error of metabolism caused by biallelic pathogenic variants in the ACAT1 (11q22.3) gene. The disease affects ketone bodies utilization and the catabolism of isoleucine. It is characterized by intermittent keto-acidotic episodes associated with vomiting, dyspnea, tachypnea, hypotonia, lethargy and coma. Episodes are frequently triggered by infections or prolonged fasting. The presentation and subsequently diagnosis of beta-ketothiolase deficiency are usually made during infancy.

Case Presentation: We report of a 7-year-old male who was hospitalized in our institution twice for episodes of fever and vomiting, requiring ICU admission on both occasions. In both cases, he arrived at our hospital with an altered mental status and a severe metabolic acidosis (pH 7.0, HCO3 8 mmol\L). He had a positive influenza PCR swab at both admissions. His symptoms and laboratory findings resolved with IV fluids alone. Urine keto bodies were elevated, as were leucine, isoleucine and valine, providing biochemical clues for the diagnosis. A genetic test revealed compound heterozygocity for the ACAT1 gene, confirming molecularly the diagnosis.

Conclusions: Although beta-ketothiolase deficiency is a disease typically diagnosed in infancy, late childhood onset can be seen as well. As keto-acidotic episodes usually follow infection or fasting periods, patients are advised to avoid the latter and seek for medical assistance in cases of prolonged fever, vomiting or decreased intake.