What is meant b y ADA deficiency? How is gene therapy a solution to this problem? Why is it not a permanent cure? What can be done for this?
ADA (adenosine deaminase) deficiency is a form of SCID (severe combined immunodeficiency)- a type of disorder that affects the immune system. The disease is caused by a mutation in a gene on chromosome 20. The gene codes for the enzyme adenosine deaminase (ADA). Without this enzyme, the body is unable to break down a toxic substance called deoxyadenosine. The toxin builds up and destroys infection-fighting immune cells called T and B lymphocytes.
Gene therapy for ADA deficiency:
Lymphocytes isolated from patient’s blood are cultured in-vitro. Functional ADA cDNA are then introduced into the cultured lymphocytes. These lymphocytes are returned back to the patient’s body.
Lymphocytes are not immortal. Therefore, repeated infusion of genetically engineered lymphocytes is required and hence it is not a permanent treatment.
The gene isolated from bone marrow cells producing ADA is introduced into cells at early embryonic stages is permanent cure.Hope this information will clear your doubts about the ADA deficiency.
It is so as normal genes are delivered to embryo through various methods.
It is so as cells are not immortal,but if ADAis introduced at early embrynic stages it could be a parmanent cure.
By introducing genetically engineered lymphocytes or a retroviral vector i.e ADA cDNA.