Acute promyelocytic leukemia (APL) is caused a chromosome abnormality that rearranges or translocates specific parts of two chromosomes. This translocation prevents myeloid cells from developing into mature white blood cells, leading to an abundance of abnormal, immature cells.
APL is unique among the leukemias distinguished by its kindliness to all-trans retinoic acid (ATRA), a derivative of vitamin A. Treatment with ATRA causes separation of the immature leukemic promyelocytes into mature granulocytes. ATRA is usually combined with anthracycline based chemotherapy resulting in a clinical remission in approximately 90% of patients.
Acute promyelocytic leukemia is a subtype of acute myelogenous leukemia (AML), a cancer of the blood and bone marrow. It is also known as acute progranulocytic leukemia; APL; AML with t(15;17)(q22;q12), PML-RARA and variants; FAB subtype M3 and M3 variant. In APL, there is an abnormal accretion of immature granulocytes called promyelocytes. The illness is characterized by a chromosomal translocation concerning the retinoic acid receptor alpha (RARα or RARA) gene and is unique from other forms of AML in its receptiveness to all trans retinoic acid (ATRA) therapy.