Question

Name the genes which fuse during translocation in Philadelphia chromosome.

Hint:

The chimeric BCR-ABL fusion gene translates into a constitutively active tyrosine kinase, which drives uncontrolled cell division in myeloid cells. The drug Imatinib (Gleevec) targets this specific kinase, serving as a classic example of targeted cancer therapy.

Answer 1

Step 1: Concept
Chronic Myelogenous Leukemia (CML) is caused by a reciprocal translocation between chromosome 9 and chromosome 22, generating an abnormally shortened chromosome 22 known as the Philadelphia chromosome.

Step 2: Identification of Fusing Genes
During this translocation event:
- The ABL1 gene (Abelson tyrosine kinase proto-oncogene) located on chromosome 9 breaks and translocates.
- It fuses with the BCR gene (Breakpoint Cluster Region) located on chromosome 22.
- This creates a chimeric oncogene, the BCR-ABL1 fusion gene, on the Philadelphia chromosome.
Final Answer: The genes that fuse are the BCR gene on chromosome 22 and the ABL gene on chromosome 9, forming the chimeric BCR-ABL oncogene.