A Novel Mutation of Beta-ketothiolase Deficiency: The First Report from Iran and Review of Literature.

Beta-ketothiolase deficiency is a rare autosomal recessive disorder characterized by an inborn error of isoleucine catabolism and affecting ketone body metabolism. Clinical features characterized by intermittent keto acidotic episodes are associated with clinical signs and symptoms of toxic encephalopathy such as lethargy, hypotonia, vomiting, tachypnea, and coma in some patients, with an onset during infancy or toddler-hood. A two months old girl presented to pediatric ward of Imam Reza Hospital in Mashhad City, Northwestern Iran in October 2016, with acute episode of fever and toxic encephalopathy with attack of vomiting, hypotonia, lethargy, tonic-clonic seizures and then a day in coma, few days after vaccination. After then similar episodes happened until 7 months age. Bio chemical tests that suggested diagnose of beta ketothiolase deficiency were attacks of ketoacidosis with urinary exertion of 2-methyl-3-hydroxybutyric acid 2-methyl aceto acetic acid tiglylglycine. In genetic assessment, we detected a novel homozygous mutation c.664A> C (p. Ser 222 Arg) in ACAT gene. This is the first report of beta ketothiolase deficiency confirmed by molecular analysis from Iran. We report on a homozygous variant in the ACAT1 gene and that is a novel mutation. We recommended carrier testing for all informative family members to recognize mutations in asymptomatic family members.