Question

A patient is suffering from ADA deficiency. Can he be cured? How?

Answer 1

ADA deficiency :

Adenosine deaminase (ADA) is the enzyme that is required for the proper functioning of the immune system.

SCID (Severe Combined Immunodeficiency) is caused by a mutation of the gene encoding the enzyme adenosine deaminase. These patients have non-functional lymphocytes, so they cannot mount immune responses against invading pathogens.

Yes, ADA deficiency can be cured by the following methods:

• Bone marrow transplantation
• Enzyme replacement therapy
• Gene therapy

Bone marrow transplantation :

SCID can be treated by bone marrow transplantation. But getting a suitable bone marrow transplant is difficult.

Enzyme replacement therapy :

The enzyme ADA can be given to the patient intravenously and this treatment is known as Enzyme Replacement therapy. But this approach is not completely curative.

Gene therapy :

Gene therapy for SCID involves the following steps:

• The lymphocytes of the patients are isolated and grown in the laboratory.
• Using a retroviral vector the complementary DNA of the ADA gene (ADA cDNA) is incorporated into the lymphocytes.
• Genetically engineered lymphocytes are then infused back into the patient’s blood.
• Now the lymphocytes could produce ADA.
• Since these lymphocytes are taken from the same patient there is no sign of rejection.
• This process is performed periodically as this is not a permanent method to cure this disorder as lymphocytes are mortal cells.
• If gene therapy is performed at the early embryonic stages using bone marrow cells, it will be a permanent cure.