Simulation · Biology · Class 12
ADA gene therapy: why the lymphocytes must be topped up
From the lesson Gene therapy in Biotechnology and its Applications. Change the values and watch what happens.
ADA gene therapy: why the lymphocytes must be topped upBiology · Class 12
The idea behind it
NCERT §10.2.2
- Gene therapy is a set of methods for correcting a gene defect diagnosed in a child or an embryo. It treats disease by putting genes into the person's cells and tissues.
- A normal gene is delivered into the person or embryo to take over the function of the non-functional gene and compensate for it.
- The first clinical gene therapy was in 1990: the patient, a girl aged 4, had adenosine deaminase (ADA) deficiency.
- ADA is an enzyme crucial for the immune system to work. The disorder arises from deletion of the gene for ADA.
- Some children with ADA deficiency can be cured by bone marrow transplantation; others receive enzyme replacement therapy, injections of working ADA. Neither approach is completely curative.
- In gene therapy, lymphocytes from the patient's blood are grown in culture outside the body, a functional ADA cDNA is introduced into them using a retroviral vector, and the cells are returned to the patient.
- These lymphocytes are not immortal, so the patient needs periodic infusions of the engineered cells.
- Putting the ADA gene, isolated from marrow cells, into cells of an early embryo could cure the disorder permanently.