Question

ADA deficiency is caused due to the

• A. Inversion
• B. Translocation
• C. Substitution
• D. Deletion

Answer 1

The correct option is D Deletion

Adenosine deaminase enzyme (ADA)
ADA (Adenosine deaminase) is the enzyme that is required for the proper functioning of the immune system. It breaks down deoxyadenosine into deoxyinosine which is not toxic to the immune cells.

ADA deficiency
ADA deficiency leads to accumulation of deoxyadenosine which is toxic to the immune cells (like lymphocytes).

Substitution mutation
Substitution mutations are those mutations in which one nucleotide is replaced by another nucleotide in the gene, thus leading to changes in the amino acid sequence of the protein product.

Deletion
Deletion mutations are the mutations in which one or more nucleotides are deleted from the gene. It is responsible for significant cases of ADA deficiency.

Translocation
Translocation is a genetic change in which a part of a chromosome breaks off and gets attached to the other chromosome or other location of the same chromosome.

Inversion
Inversion is a genetic change in which a region of DNA breaks off at two places and the DNA gets reversed and re-inserted.

Final answer
(A) Deletion