Gene therapy

Question 1

What are gene therapy drugs?

Answer 1

• change or add a healthy copy of a gene to produce the correct protein to improve patients’ health
  (costly, only done once, possible side effects)

Question 2

How is gene therapy used in the eyes?

Answer 2

disease: hereditary progressive vision loss
- direct gene therapy to the cells of the retina (gene: RPE65)
- uses a naturally occurring viral vector

Question 3

How was a clinical trial for gene therapy for eyes conducted?

Answer 3

• 41 people (Luxturna, approved in 2017)
• the retina (thin layer back of the eye) is detached from surrounding blood vessels by spraying it with saline solution
• the missing gene is injected into he light-sensing cells of the retina where it starts producing protein and repairs damaged cells (retina reattached itself)
• the gene does not insert into the human chromosome

Question 4

who was the retinal gene therapy approved for?

Answer 4

children with inherited retinal disease (1 year or older)

• significant vision improvement maintained for over a year

Question 5

How was the efficacy of the retinal gene therapy measured?

Answer 5

patients navigated obstacle courses in low-light levels

Question 6

What is hemoglobin?

Answer 6

a protein complex made of alpha-globin and beta-globin

Question 7

What happens if you have an altered HBB gene?

Answer 7

HBB (hemoglobin subunit beta gene) encodes the beta-globin protein
- altered beta-globin proteins: stick to one another forming long fibers, making red blood cells stiff and misshaped

Question 8

Who was Victoria Gray?

Answer 8

• the first patient to receive a gene editing clinical trial for sickle cell disease

Question 9

How was Deidre Williams free of sickle cell disease?

Answer 9

stem cell transplant from a donor relative

Question 10

Which gene editing technology won a nobel prize in 2020?

Answer 10

CRISPR: molecular scissors to edit human genes in 3 ways

Question 11

What are the ways CRISPR can edit human genes?

Answer 11

• disrupt (make a gene stop working)
• delete
• correct or insert (cut out and replace)

Question 12

What is Casgevy?

Answer 12

gene therapy outside of the patient by using CRISPR for sickle cell disease
- remove cells (blood stem cells)
- perform gene editing
- deliver edited cells to the patient
- edited stem cells expand in numbers inside the patient

Question 13

There are different gene mutations for sickle cell disease, how is a universal gene editing therapy achieved?

Answer 13

• Gene editing is not of the hemoglobin B gene
• gene editing of the gene that controls fetal hemoglobin (hemoglobin in babies)
• indirect approach

Question 14

How was the gene editing trial conducted?

Answer 14

• 30 people
• 29 received edited cells
• no pain crises for over a year
• fetal hemoglobin elevated
• gene editing remains over 70%

Question 15

How many people have rare diseases?

Answer 15

• 300 million
• 72% of all rare diseases are genetic