Question

State the steps involved in the process of gene therapy for the treatment of ADA-deficiency.

Answer 1

1. Stem cells from the bone marrow, responsible for producing lymphocytes in ADA-deficient patients, are extracted. These cells harbor the faulty ADA gene.
2. A retrovirus, a specialized RNA virus, serves as a vector in this process.
3. The normal ADA gene is replicated through recombinant DNA technology and incorporated into the nucleic acid of a retrovirus, engineered to be non-pathogenic.
4. The bone marrow stem cells from ADA-deficient individuals undergo infection with the retrovirus.
5. The virus introduces its nucleic acid (rDNA), which includes the functional ADA gene, into the chromosome of the stem cell.
6. This provides these bone marrow stem cells with a functional copy of the gene alongside the pre-existing defective gene.
7. The treated stem cells continue to replicate over the patient's lifetime. Possessing a fully functional ADA gene, they produce the ADA enzyme. These modified cells supply the lacking enzyme, leading to the cure of the ADA-deficient patient.