Psychotic disorders: 22q11.2 deletion and psychosis: practice question

A Psychiatry 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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Psychiatry · Psychotic disorders: 22q11.2 deletion and psychosis

Sample item

A 19-year-old with a first psychotic episode had cleft palate repair in infancy, a congenital heart defect, recurrent infections, hypocalcaemia in childhood, hypernasal speech and long-standing learning difficulty. Which test is most likely to explain his illness?

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

The answer and the reasoning

C. Chromosomal microarray or FISH for 22q11.2 microdeletion

Velocardiofacial (22q11.2 deletion) syndrome combines palatal and cardiac anomalies, hypocalcaemia from parathyroid hypoplasia, immune deficiency and learning difficulty. About a quarter of carriers develop schizophrenia-spectrum illness, which makes this one of the strongest known genetic risks.

Option by option

  • A. FMR1 gene analysis for CGG repeat expansion

    Fragile X causes long face, macro-orchidism and intellectual disability without these structural defects.

  • B. HTT gene analysis for CAG repeat expansion

    Huntington disease is an adult-onset movement disorder and does not cause congenital malformations.

  • C. Chromosomal microarray or FISH for 22q11.2 microdeletion (correct)

    Correct. The cluster of palatal, cardiac, parathyroid and immune features points to a 22q11.2 deletion.

  • D. Karyotype for trisomy 21

    Trisomy 21 gives characteristic facies and hypotonia, and is not linked with cleft palate with hypocalcaemia.

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 Psychiatry question

What is the answer to this Psychiatry question?

The best answer is C, Chromosomal microarray or FISH for 22q11.2 microdeletion. Velocardiofacial (22q11.

Why is "FMR1 gene analysis for CGG repeat expansion" not the answer?

Fragile X causes long face, macro-orchidism and intellectual disability without these structural defects.

Why is "HTT gene analysis for CAG repeat expansion" not the answer?

Huntington disease is an adult-onset movement disorder and does not cause congenital malformations.

Why is "Karyotype for trisomy 21" not the answer?

Trisomy 21 gives characteristic facies and hypotonia, and is not linked with cleft palate with hypocalcaemia.

What concept does this question test?

It tests Psychotic disorders: 22q11.2 deletion and psychosis in Psychiatry. 2 deletion) syndrome combines palatal and cardiac anomalies, hypocalcaemia from parathyroid hypoplasia, immune deficiency and learning difficulty. About a quarter of carriers develop schizophrenia-spectrum illness, which makes this one of the strongest known genetic risks.

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 Psychotic disorders: 22q11.2 deletion and psychosis?

Learn each diagnosis by its core features and its first-line treatment. Then use the flashcards and the other Psychiatry 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.