Question

Arrange the steps of ADA-deficiency treatment in sequence:
I. The lymphocytes with ADA cDNA is returned to the patient
II. The lymphocytes from the blood of the patient are grown in culture outside the body
III. A functional ADA cDNA (using retroviral vector) is introduced into the lymphocytes

• A. $I\to III\to II$
• B. $I\to II\to III$
• C. $II\to I\to III$
• D. $III\to II\to I$

Answer 1

Answer: (D)

$III\to II\to I$

Adenosine deaminase deficiency or ADA deficiency is an autosomal recessive disorder that causes immunodeficiency. Gene therapy is a method to treat this. A functional ADA complementary DNA is inserted to the lymphocytes and then grown in an artificial culture. After the growth ADA cDNA is returned to the patient.

So, the correct answer is 'III→II→I'.