Question

Uncontrolled action of which of the following enzymes plays a major etiological role in chronic myeloid leukemia?

• A. Tyrosine kinase
• B. Cholinesterase
• C. Galactokinase
• D. Bradykinin

Hint:

Think of the BCR-ABL fusion protein created by the Philadelphia chromosome.

Answer 1

The Correct Option is A

This question asks which enzyme's uncontrolled activity causes chronic myeloid leukemia.

1. Tyrosine kinase: The Philadelphia chromosome fuses the BCR and ABL genes, producing a permanently active BCR-ABL tyrosine kinase that continuously drives abnormal myeloid cell proliferation.
2. Cholinesterase: This enzyme breaks down acetylcholine at synapses and has no role in leukemia development.
3. Galactokinase: This enzyme is involved in galactose metabolism, and its deficiency causes galactosemia, unrelated to leukemia.
4. Bradykinin: This is a peptide involved in inflammation, not an enzyme, and has no role in causing this disease.

The BCR-ABL fusion protein's constitutively active tyrosine kinase activity is the well established driver of chronic myeloid leukemia.

Let's summarize:

• The Philadelphia chromosome creates the BCR-ABL fusion gene.
• Its product is a permanently active tyrosine kinase that drives uncontrolled myeloid cell growth.

So the enzyme responsible is tyrosine kinase.