Which translocation is associated with APL?

Which translocation is associated with APL?

• A. t(9;22)
• B. t(8;21)
• C. t(14;18)
• D. t(15;17)

Answer: (D)

In acute promyelocytic leukemia, a chromosome 15 to 17 translocation creates the PML-RARA fusion gene. This fusion protein disrupts retinoic acid signaling, causing a block in the maturation of myeloid precursors and resulting in the accumulation of abnormal promyelocytes. That arrested differentiation explains the characteristic appearance of APL and its unique clinical features, including a tendency toward coagulopathy. Importantly, this fusion is why all-trans retinoic acid therapy is so effective: ATRA binds the abnormal receptor and releases the block, allowing the leukemic cells to mature and die. Arsenic trioxide can also target this fusion protein to promote remission. The other translocations listed are associated with different leukemias or lymphomas (for example, BCR-ABL with CML/ALL, other AML subtypes, or IgH-BCL2 with follicular lymphoma) and do not define APL. Therefore, the translocation linked to APL is the one between chromosomes 15 and 17.

In acute promyelocytic leukemia, a chromosome 15 to 17 translocation creates the PML-RARA fusion gene. This fusion protein disrupts retinoic acid signaling, causing a block in the maturation of myeloid precursors and resulting in the accumulation of abnormal promyelocytes. That arrested differentiation explains the characteristic appearance of APL and its unique clinical features, including a tendency toward coagulopathy. Importantly, this fusion is why all-trans retinoic acid therapy is so effective: ATRA binds the abnormal receptor and releases the block, allowing the leukemic cells to mature and die. Arsenic trioxide can also target this fusion protein to promote remission. The other translocations listed are associated with different leukemias or lymphomas (for example, BCR-ABL with CML/ALL, other AML subtypes, or IgH-BCL2 with follicular lymphoma) and do not define APL. Therefore, the translocation linked to APL is the one between chromosomes 15 and 17.