What chromosomal abnormality is associated with Acute Promyelocytic Leukemia (APL)?

Acute Promyelocytic Leukemia (APL) is primarily characterized by a specific chromosomal abnormality, which involves a balanced translocation between chromosomes 15 and 17, denoted as t(15;17). This translocation results in the fusion of the promyelocytic leukemia (PML) gene on chromosome 15 with the retinoic acid receptor alpha (RARA) gene on chromosome 17, creating the PML-RARA fusion gene. This fusion protein is crucial in the pathogenesis of APL, as it interferes with normal myeloid differentiation, leading to the accumulation of promyelocytes in the bone marrow and peripheral blood.

The importance of this translocation in APL is further underscored by the therapeutic strategies employed, which often involve all-trans retinoic acid (ATRA) to induce differentiation of the promyelocytes into mature granulocytes. This treatment is distinct for APL and is directly linked to the presence of the t(15;17) translocation, making it a hallmark of the disease.

Other chromosomal abnormalities listed do not relate to APL. The t(8;14) translocation is associated with Burkitt lymphoma, the t(9;22)