Question

which best describes ex vivo gene therapy?
a cells are first removed from the patient and then the proper gene is inserted into those cells.
b the gene of interest is introduced directly into the bone marrow.
c the gene of interest is introduced directly into the patient and taken up by the patients cells.
d cells are first removed from the patient and then the existing gene is edited.

Explanation:

To determine the correct description of ex vivo gene therapy, we analyze each option:

• Option a: Ex vivo gene therapy involves removing cells from the patient, modifying them (inserting the proper gene), and then reintroducing them. This matches the definition.
• Option b: Introducing the gene directly into the bone marrow is not the defining characteristic of ex vivo (which requires cell removal first).
• Option c: Direct introduction into the patient without prior cell removal is in vivo gene therapy, not ex vivo.
• Option d: Ex vivo gene therapy typically involves inserting a new gene, not just editing an existing one, and the key step of cell removal and then gene insertion (not just editing) is better captured in option a.

Answer:

a. Cells are first removed from the patient and then the proper gene is inserted into those cells.