Lipid metabolism: fetal LCHAD deficiency and acute fatty liver of pregnancy: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Lipid metabolism: fetal LCHAD deficiency and acute fatty liver of pregnancy

Sample item

A woman at 35 weeks of gestation has vomiting, jaundice, hypoglycaemia and coagulopathy from acute fatty liver of pregnancy. Her newborn later develops hypoketotic hypoglycaemia, cardiomyopathy and retinopathy. Which fetal enzyme defect is classically linked to the mother's illness?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Long-chain 3-hydroxyacyl-CoA dehydrogenase

Fetal deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase, part of the mitochondrial trifunctional protein, is associated with acute fatty liver of pregnancy in heterozygous mothers. Abnormal long-chain hydroxy fatty acids from the fetus are thought to injure the maternal liver. The child has a fatty acid oxidation disorder.

Option by option

  • A. Carnitine palmitoyltransferase II

    Carnitine palmitoyltransferase II deficiency causes muscle disease in adults or severe multiorgan disease in neonates, but not this association.

  • B. Medium-chain acyl-CoA dehydrogenase

    Medium-chain acyl-CoA dehydrogenase deficiency causes hypoketotic hypoglycaemia in children but is not linked to the maternal liver illness.

  • C. Carnitine-acylcarnitine translocase

    Carnitine-acylcarnitine translocase deficiency is a rare neonatal disorder and is not the classic link to maternal liver disease.

  • D. Long-chain 3-hydroxyacyl-CoA dehydrogenase (correct)

    Correct. Fetal LCHAD deficiency is the classic association with maternal acute fatty liver of pregnancy.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Long-chain 3-hydroxyacyl-CoA dehydrogenase. Fetal deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase, part of the mitochondrial trifunctional protein, is associated with acute fatty liver of pregnancy in heterozygous mothers.

Why is "Carnitine palmitoyltransferase II" not the answer?

Carnitine palmitoyltransferase II deficiency causes muscle disease in adults or severe multiorgan disease in neonates, but not this association.

Why is "Medium-chain acyl-CoA dehydrogenase" not the answer?

Medium-chain acyl-CoA dehydrogenase deficiency causes hypoketotic hypoglycaemia in children but is not linked to the maternal liver illness.

Why is "Carnitine-acylcarnitine translocase" not the answer?

Carnitine-acylcarnitine translocase deficiency is a rare neonatal disorder and is not the classic link to maternal liver disease.

What concept does this question test?

It tests Lipid metabolism: fetal LCHAD deficiency and acute fatty liver of pregnancy in Biochemistry. Abnormal long-chain hydroxy fatty acids from the fetus are thought to injure the maternal liver. The child has a fatty acid oxidation disorder.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Lipid metabolism: fetal LCHAD deficiency and acute fatty liver of pregnancy?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.