Metabolic: Tay-Sachs disease: practice question

A Pediatrics 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.

Try it

Pediatrics · Metabolic: Tay-Sachs disease

Sample item

An infant of Ashkenazi Jewish ancestry shows regression at 6 months, exaggerated startle, macular cherry-red spot and no organomegaly. What is the deficient enzyme?

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

The answer and the reasoning

B. Hexosaminidase A

Tay-Sachs disease is GM2 gangliosidosis due to hexosaminidase A deficiency, with a cherry-red macula, hyperacusis and macrocephaly but no hepatosplenomegaly. Niemann-Pick also has a cherry-red spot but with organomegaly. There is no cure.

Option by option

  • A. Galactocerebrosidase

    Galactocerebrosidase deficiency causes Krabbe disease.

  • B. Hexosaminidase A (correct)

    Correct. Hexosaminidase A is deficient.

  • C. Sphingomyelinase

    Sphingomyelinase deficiency causes Niemann-Pick, which has organomegaly.

  • D. Glucocerebrosidase

    Glucocerebrosidase deficiency causes Gaucher disease.

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.

More Pediatrics questions

Questions about this Pediatrics question

What is the answer to this Pediatrics question?

The best answer is B, Hexosaminidase A. Tay-Sachs disease is GM2 gangliosidosis due to hexosaminidase A deficiency, with a cherry-red macula, hyperacusis and macrocephaly but no hepatosplenomegaly.

Why is "Galactocerebrosidase" not the answer?

Galactocerebrosidase deficiency causes Krabbe disease.

Why is "Sphingomyelinase" not the answer?

Sphingomyelinase deficiency causes Niemann-Pick, which has organomegaly.

Why is "Glucocerebrosidase" not the answer?

Glucocerebrosidase deficiency causes Gaucher disease.

What concept does this question test?

It tests Metabolic: Tay-Sachs disease in Pediatrics. Niemann-Pick also has a cherry-red spot but with organomegaly. There is no cure.

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 Metabolic: Tay-Sachs disease?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.