Complications and emergencies: genetics of malignant hyperthermia: practice question

A Anaesthesia 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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Anaesthesia · Complications and emergencies: genetics of malignant hyperthermia

Sample item

A 20-year-old develops rigidity, rising temperature and tachycardia after volatile anaesthesia, and a paternal uncle died during a similar operation. How is susceptibility inherited?

AAutosomal recessive defect of plasma cholinesteraseBAutosomal recessive defect of the ryanodine receptorCAutosomal dominant defect of the ryanodine receptorDX-linked recessive defect of dystrophin

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

The answer and the reasoning

C. Autosomal dominant defect of the ryanodine receptor

Malignant hyperthermia susceptibility is inherited as an autosomal dominant trait, most often through a mutation in the RYR1 gene for the skeletal muscle ryanodine receptor. Triggers are volatile agents and succinylcholine. Plasma cholinesterase deficiency is autosomal recessive.

Option by option

A. Autosomal recessive defect of plasma cholinesterase
Cholinesterase deficiency prolongs succinylcholine but does not cause hyperthermia.
B. Autosomal recessive defect of the ryanodine receptor
The ryanodine receptor defect is dominant, not recessive.
C. Autosomal dominant defect of the ryanodine receptor (correct)
Correct. It is autosomal dominant and involves the ryanodine receptor.
D. X-linked recessive defect of dystrophin
Dystrophin defects cause Duchenne dystrophy, not this syndrome.

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.

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, Autosomal dominant defect of the ryanodine receptor. Malignant hyperthermia susceptibility is inherited as an autosomal dominant trait, most often through a mutation in the RYR1 gene for the skeletal muscle ryanodine receptor.

Why is "Autosomal recessive defect of plasma cholinesterase" not the answer?

Cholinesterase deficiency prolongs succinylcholine but does not cause hyperthermia.

Why is "Autosomal recessive defect of the ryanodine receptor" not the answer?

The ryanodine receptor defect is dominant, not recessive.

Why is "X-linked recessive defect of dystrophin" not the answer?

Dystrophin defects cause Duchenne dystrophy, not this syndrome.

What concept does this question test?

It tests Complications and emergencies: genetics of malignant hyperthermia in Anaesthesia. Triggers are volatile agents and succinylcholine. Plasma cholinesterase deficiency is autosomal recessive.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Complications and emergencies: genetics of malignant hyperthermia?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.