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MCAD deficiency — RACP Paediatrics MCQ

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HardGeneticsMCAD deficiencyRACP Paediatrics

A previously well 14-month-old presents with hypoketotic hypoglycaemia, hepatomegaly, and metabolic acidosis during a gastroenteritis illness. The child had fasted for 18 hours. Acylcarnitine profile shows elevated C8 (octanoylcarnitine). What is the most likely diagnosis?

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Correct answer: B — Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

Hypoketotic hypoglycaemia (inappropriately low ketones for the degree of hypoglycaemia) precipitated by fasting or illness with elevated C8 on acylcarnitine profile is diagnostic of MCAD deficiency, the most common fatty acid oxidation disorder. It is detected on newborn screening in Australia. Management is avoidance of prolonged fasting and emergency management plans during illness.

Reference: RACP Paediatric Curriculum – Metabolic; RCH Melbourne – 2023 – Metabolic Disease CPG