B3 WK2 SFM Gene Therapy

What is the main advantage of AAV vectors?

Durable trans gene expression in nondividing cells; AAV can transduce both dividing and nondividing cells

What is the typical genomic factor of an AAV transgene?

Most episomal, meaning it remains outside the host genome

Which vector requires cell division for efficient delivery?

y-Retroviral vectors

What is the main advantage of y-retroviral vectors?

Stable gene addition through integration into the host genome

How do lentivrial vectors differ from y-retroviral vectors?

Lentiviral vectors can transduce nondividing cells and integrate into the host genome

What is the major advantage of adenoviral vectors?

They can deliver a large DNA payload; transgene DNA is mostly episomal

What is the main advantage of lipid nanoparticles (LNPs)?

They deliver RNA or other cargo without requiring genomic integration

What is electroportation used for in gene therapy?

Direct delivery of therapeutic cargo into cells using electrical pulses

Which delivery method is used for Casgevy cell editing?

Electroportation of ex vivo hematopoietic stem cells.

What distinguished in vivo from ex vivo gene therapy?

In vivo modifies cells inside the patient while ex vivo modifies collected cells outside the body

Which delivery system and gene are used by Luxturna?

AAV2 delivers functional RPE65 directly to retinal cells in vivo

WHy does Luxturna require viable retinal cells?

The therapy supplies functional RPE65 but cannot restore retinal cells that have already been lost.

Which delivery and gene are used by Zolgensma?

AAV9 delivers functional SMN1 in vivo to treat muscular atrophy

Does Zolgensma correct the endogenous SMN1 mutation?

No, it adds a functional SMN1 gene rather than repairing the original locus

Why is early treatment important in spinal muscular atrophy?

Lost motor neurons may not be recoverable

Why are hematopoietic stem cells (HSCs) useful for ex vivo therapy?

They self-renew and continually produce blood cells carrying the therapeutic change

How does Casgevy treat sickle cell disease?

In disrupts an erythroid-specific BCL11A enhancer, increasing fetal hemoglobin (HbF)

Does Casgevy correct the HBB mutation causing sickle cell disease?

No. It edits a regulatory element to increase HbF and reduce sickling

How does Zynteglo treat B-thalassemia?

It adds a functional B-glob in gene using a Lentiviral vectors in autologous HSCs.

What is the key difference between Casgevy and Zynteglo?

Casgevy edits a regulatory element to increase HbF; Zynteglo adds a functional B-globin gene.

How do CAR-T cells recognize cancer?

They recognize intact cell-surface antigens independently of MHC presentation

How do TCR-T cells recognize cancer?

They recognize specific peptides presented by MHC molecules

What are the basic steps for CAR-T or TCR-T therapy?

Collect T cells, introduce the receptor gene ex vivo, expand cells and reinfuse them.

What two components direct CRISPR/Cas9 targeting?

A compatible PAM sequence and a guide RNA complementary to the target DNA

What does PAM stand for?

Protospacer Adjacent Motif

What does Cas9 do after target recognition?

It creates a double-strand DNA break about 3 base pairs upstream of the PAM

Which cellular process actually produces the CRISPR edit?

Cellular DNA repair following the Cas9-induced break

What is non homologous joining (NHEJ)?

A repair pathway that directly rejoins DNA ends and often produced small insertions or deletions

In which cells can NHEJ function?

Both dividing and nondividing

What is homologous-directed repair (HDR)?

A repair pathway that uses a homologous DNA template to install a precise change

When is HDR generally favored?

During the S and G2 phases of cell cycle

What does an adenine base editor change?

A→G

What does a cytidine base editor change?

C→T

What can prime editing do?

Replace or insert about 40-50 Bo and delete up to 100 Bo

Why does tissue tropsim matter in gene therapy?

It determines which cell types a vector preferentially transduces

Why can immune responses complicate AAV therapy?

Immunity can limit delivery or expression and make repeat dosing difficult

Why is redoing sometimes difficult with viral vectors?

Pre-existing or treatment-induced immunity may interfere with subsequent administration

What is Insertional mutagenesis?

Integration of vector DNA that disrupts or alters host genes, potentially causing harmful effects

Which gene therapy vectors carry Insertional mutagenesis risk?

Y-retroviral and Lentiviral vectors