Enzyme deficiency

MCAD deficiency

What is missing: Medium-chain acyl-CoA dehydrogenase.

Presentation

Vomiting, lethargy and coma during a fast or illness in a young child

Why the signs follow

The giveaway is hypoketotic hypoglycemia: the patient is hypoglycaemic and yet has almost no ketones, because ketones are made from the acetyl-CoA that β-oxidation would have supplied. Any fasting hypoglycemia without ketones points at fat oxidation.

Written for exam preparation, not for diagnosis.

β-Oxidation pathway All control points