Question

Describe the gene therapy produced for an ADA-deficient patient.

Answer 1

Hint: Process of inserting genes into cells to treat diseases is called gene therapy. The first apparently successful gene therapy was started in September \[14,1990\] . Patient Ashanthi DaSilva was only $4$ years old and had a very rare recessive hereditary disease, adenosine deaminase deficiency (ADA).

Complete answer:
ADA helps conserve purines while breaking down nucleic acids and is a household enzyme that is synthesized in a wide variety of cells. System. As a result, patients with ADA develop severe combined immune deficiency. This severe disorder is well suited for gene therapy for many reasons: The ADA gene is small and has previously been cloned and examined in detail; The target cells are T cells, which are readily available and easy to cultivate, and allow ex vivo gene therapy.
Now let’s understand steps involved in general therapy
A plasmid vector carrying proviral DNA was selected. Part of the proviral DNA was replaced by the ADA gene and the gene coding for antibiotic resistance and then cloned. The antibiotic resistance gene helps in selecting the clone you want with the ADA gene.
These cells were transfected with the ADA gene, exposing billions of retroviruses carrying the gene. Genetically engineered lymphocytes were implanted in culture to confirm ADA gene expression and returned to the patient.
These lymphocytes continue to circulate and synthesize ADA, increasing the patient's ability to produce antibodies.

Note: Lymphocytes have a short life span (live only a few months), so frequent transfusions are required.
In $1995$ , the ADA gene was transferred to stem cells from the umbilical cord blood during baby birth. The modified cells were returned to the baby four days after birth. This creates a constant population of cells that produce the ADA gene and therefore increase the patient's ability to produce antibodies.
SCID-It is a rare inherited immune disorder associated with T lymphocytes and (to a lesser extent) B lymphocyte dysfunction. T lymphocytes are essential to immunity.