A 40-year-old man has AML with 30% blasts, monocytic components, and marrow eosinophils containing large basophilic and eosinophilic granules. Cytogenetics show inv(16)(p13.1q22). Which fusion gene is formed?

• A KMT2A-AFF1
• B RUNX1-RUNX1T1
• C PML-RARA
• D CBFB-MYH11 ✓

Explanation

inv(16) disrupts the CBFB gene at 16q22 and fuses it to MYH11 (smooth muscle myosin heavy chain) at 16p13, giving AML with inv(16), formerly FAB M4eo. The abnormal marrow eosinophils with mixed basophilic granules are the morphologic clue. RUNX1-RUNX1T1 results from t(8;21), PML-RARA from t(15;17), and KMT2D-AFF1 from t(4;11), typically seen in infant and adult ALL.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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