APL involves a fusion gene created by t(15;17). Which fusion gene is produced by this translocation?

APL involves a fusion gene created by t(15;17). Which fusion gene is produced by this translocation?

• A. PML-RARA
• B. BCR-ABL
• C. CBFB-MYH11
• D. ETV6-RUNX1

Answer: (A)

In APL, the defining genetic event is the t(15;17) translocation that fuses the PML gene on chromosome 15 with the RARA gene on chromosome 17, creating the PML-RARA fusion gene. This chimeric protein disrupts retinoic acid receptor signaling and blocks differentiation at the promyelocyte stage, leading to accumulation of immature cells. This fusion is also the target of therapy with all-trans retinoic acid, which can relieve the block and drive differentiation, making this subtype highly curable with appropriate treatment. The other fusions listed are associated with different leukemias: BCR-ABL with CML (and some ALL), CBFB-MYH11 with AML with abnormal eosinophils, and ETV6-RUNX1 with pediatric B-ALL.

In APL, the defining genetic event is the t(15;17) translocation that fuses the PML gene on chromosome 15 with the RARA gene on chromosome 17, creating the PML-RARA fusion gene. This chimeric protein disrupts retinoic acid receptor signaling and blocks differentiation at the promyelocyte stage, leading to accumulation of immature cells. This fusion is also the target of therapy with all-trans retinoic acid, which can relieve the block and drive differentiation, making this subtype highly curable with appropriate treatment. The other fusions listed are associated with different leukemias: BCR-ABL with CML (and some ALL), CBFB-MYH11 with AML with abnormal eosinophils, and ETV6-RUNX1 with pediatric B-ALL.