The first clinical gene therapy was given for treating Chickenpox, Adenosine deaminase deficiency, Rheumatoid arthritis, or Diabetes mellitus?

The first human gene therapy trial was conducted at the National Institutes of Health in Bethesda, Maryland, in 1990 on a four-year-old girl suffering from ADA deficiency. A functional ADA gene was introduced ex vivo in bone marrow cells of the child through an engineered retrovirus containing a functional ADA gene. The treated cells were reintroduced into the patient’s marrow. So, the correct answer is option D.