NEET PG / USMLE – MCQ 13

A 4-month-old boy is brought to the emergency department 30 minutes after becoming unresponsive. He has a 1-day history of poor breast-feeding and vomiting. He is unresponsive to stimuli. Physical examination shows mild hepatomegaly. Serum studies show hypoglycemia and absence of ketones. The patient becomes responsive following an intravenous bolus of glucose. Urine studies show no ketones and increased concentrations of C6 and C8 carbon chain dicarboxylic acids. A deficiency of which of the following enzyme activities is the most likely cause of the findings in this patient?
(A) Fructose-1,6-bisphosphatase
(B) Glucose-6-phosphatase
(C) Medium-chain acyl-CoA dehydrogenase
(D) Methylmalonyl-CoA mutase
(E) Ornithine carbamoyltransferase

Correct answer : (C) Medium-chain acyl-CoA dehydrogenase

Hypoglycemia and absence of ketone bodies are found both in option b and option c. But accumulation of dicarboxylic acid is specific to Medium-chain acyl-CoA dehydrogenase deficiency. Hence answer is option “C”