A 35-year-old presents with fatigue, splenomegaly, and a WBC of 120,000/µL with predominantly mature granulocytes. Philadelphia chromosome is detected. The BCR-ABL fusion protein in CML constitutively activates which kinase?

• A JAK2 tyrosine kinase
• B FLT3 tyrosine kinase
• C ABL tyrosine kinase ✓
• D KIT tyrosine kinase

Explanation

The t(9;22) translocation fuses BCR to ABL, producing a constitutively active ABL tyrosine kinase that drives uncontrolled myeloid proliferation. JAK2 mutations are characteristic of polycythemia vera and other myeloproliferative neoplasms; FLT3 ITD mutations are found in AML; KIT mutations are found in gastrointestinal stromal tumors and some AML subtypes.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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