A Rare Cause of Life-Threatening Ketoacidosis: Novel Compound Heterozygous OXCT1 Mutations Causing Succinyl-CoA:3-Ketoacid CoA Transferase Deficiency

Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency is a rare inborn error of ketone body utilization, characterized by episodic or permanent ketosis. SCOT deficiency is caused by mutations in the OXCT1 gene, which is mapped to 5p13 and consists of 17 exons. A 12-month-old girl presented with severe ketoacidosis and was treated with continuous renal replacement therapy. She had two previously unrecognized mild-form episodes of ketoacidosis followed by febrile illness. While high levels of ketone bodies were found in her blood and urine, other laboratory investigations, including serum glucose, were unremarkable. We identified novel compound heterozygous mutations in OXCT1:c.1118T>G (p.Ile373Ser) and a large deletion ranging from exon 8 to 16 through targeted exome sequencing and microarray analysis. This is the first Korean case of SCOT deficiency caused by novel mutations in OXCT1, resulting in life-threatening ketoacidosis. In patients with unexplained episodic ketosis, or high anion gap metabolic acidosis in infancy, an inherited disorder in ketone body metabolism should be suspected.