A permanent cure for ADA deficiency could be:

Which kind of therapy was given in 1990 to a four-year-old girl with Adenosine Deaminase (ADA) deficiency?

The genetic defect-Adenosine Deaminase (ADA) deficiency may be cured permanently by

(1) periodic infusion of genetically engineered lymphocytes having functional ADA cDNA 

(2) administering adenosine deaminase activators

(3) introducing bone marrow genes producing ADA into cells at early embryonic stages

(4) enzyme replacement therapy

An example of gene therapy is 

Adenosine deaminase (ADA deficiency) could be permanently cure, if the gene isolated from marrow cells producing ADA is introduced into cell at

(1) early embryonic stages

(2) Late embryonic stages

(3) early childhood

(4) None of the above