Question 1

Which of the following is a foundational criterion for a disease to be considered for gene therapy using CRISPR/Cas9?

Accepted Answer

The disease must be caused by a monogenic disorder with a clear genotype-phenotype correlation.

Question 2

In the natural CRISPR pathway in bacteria, what is the primary function of the Cas9 protein?

Accepted Answer

To create a double-strand break in invading DNA.

Question 3

Which step occurs first in the CRISPR/Cas9 gene editing process?

Accepted Answer

The Cas9 protein and guide RNA bind together to become active.

Question 4

A patient with sickle cell disease is treated with CRISPR/Cas9 gene therapy. Which mechanism is most likely used to correct the mutation?

Accepted Answer

In-situ correction via base editing to repair the mutated gene.

Question 5

Why is genomic integrity a critical consideration in CRISPR/Cas9 gene therapy?

Accepted Answer

To prevent off-target cuts and chromosomal translocations.

Question 6

Which of the following best describes the role of the PAM sequence in CRISPR/Cas9 gene editing?

Accepted Answer

It is required for Cas9 to recognize and bind to the target DNA.

Question 7

A researcher wants to silence a gene that causes a gain-of-function disease. Which CRISPR/Cas9 strategy should be used?

Accepted Answer

Disruption of the target gene.

Question 8

Which delivery method is most appropriate for gene therapy targeting liver cells in vivo?

Accepted Answer

A viral or lipid nanoparticle (LNP) delivery vehicle.

Question 9

What is the main advantage of ex vivo gene therapy compared to in vivo gene therapy?

Accepted Answer

Cells can be edited outside the body and screened before re-engraftment.

Question 10

Which repair mechanism is used by cells to fix the double-strand break created by Cas9?

Accepted Answer

Non-homologous end joining (NHEJ) or homology-directed repair (HDR).

Question 11

A gene therapy requires at least 30% of cells to be 'fixed' to reverse symptoms. This is an example of which foundational criterion?

Accepted Answer

Phenotypic correction threshold.

Question 12

Which of the following best explains why CRISPR/Cas9 is considered a revolutionary tool in genetic engineering?

Accepted Answer

It allows for precise, targeted modifications of DNA sequences.

Question 13

Which of the following is a potential risk associated with CRISPR/Cas9 gene editing?

Accepted Answer

Off-target effects leading to unintended genetic changes.

Question 14

A scientist is designing a CRISPR/Cas9 experiment. Which equation would best represent the probability $$P of a $$successful edit if the efficiency of delivery is $$E$$ and the rate of off-target effects is $$O$$?

Accepted Answer

$$P = E 	imes (1 - O)$$

Question 15

Which of the following scenarios best illustrates the concept of 'tissue access and tropism' in gene therapy?

Accepted Answer

Using a viral vector that specifically targets liver cells for gene delivery.

Question 16

Which of the following is NOT a strategic mechanism for gene therapy using CRISPR/Cas9?

Accepted Answer

Amplification of the target gene.

Question 17

In the context of CRISPR/Cas9, what does 'durability of effect' refer to?

Accepted Answer

The genetic modification remains stable and active throughout the lifespan of the target cell population.

Question 18

Which of the following best describes the order of steps in CRISPR/Cas9 gene editing?

Accepted Answer

Cas9 protein and guide RNA bind, complex finds PAM, DNA unwinding, guide RNA pairs, Cas9 cuts, cell repairs.

Question 19

A gene therapy trial fails because the genetic modification is not maintained in the target cells over time. Which foundational criterion was not met?

Accepted Answer

Durability of effect.

Question 20

Which of the following is a real-world application of CRISPR/Cas9 gene editing?

Accepted Answer

Correcting the mutation responsible for sickle cell disease in human stem cells.

CRISPR/Cas9 and Gene Therapy: Mechanisms and Applications

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