Acute promyelocytic leukemia (APL) is an aggressive type of acute myeloid leukemia in which there are too many immature blood-forming cells (promyelocytes) in the blood and bone marrow. This build up of promyelocytes leads to a shortage of normal white and red blood cells and platelets in the body. The signs and symptoms of APL include an increased risk to both bleed and form blood clots. Individuals may also experience excessive tiredness, pain in affected areas, loss of appetite, and weight loss. APL usually occurs in middle-aged adults, but can be diagnosed at any age. It is caused by a mutation that is acquired over a person's lifetime, usually involving a translocation between chromosomes 15 and 17. Treatment may include the use of all-trans retinoic acid (ATRA) and arsenic trioxide or anthracycline-based chemotherapy.

APL is caused by a chromosomal translocation (rearrangement of material) that occurs in some of the body's cells during a person's lifetime (a somatic mutation). The translocation involves the fusion of two genes: the PML gene on chromosome 15 and the RARA gene on chromosome 17. The protein produced by this fusion is referred to as PML-RARα. The PML-RARα protein functions differently than what is typically produced by the normal PML and RARA genes. As a result of the abnormal function, blood cells become "stuck" at the promyelocyte stage and they proliferate (reproduce) abnormally. Excess promyelocytes then accumulate in the bone marrow, disrupting the formation of normal white blood cells and leading to APL. Translocations involving the RARA gene and other genes have been identified in only a few cases of APL.

Most cases of APL are treated with an anthracycline chemotherapy drug (daunorubicin or idarubicin) plus the non-chemotherapy drug, all-trans-retinoic acid (ATRA), which is a relative of vitamin A. This treatment leads to remission in 80% to 90% of patients.

Patients who cannot tolerate an anthracycline drug may get ATRA plus another drug called arsenic trioxide. Arsenic trioxide has also proven to be an effective alternative for the 20% to 30% of patients with APL who don't respond to initial treatment or who relapse. If treatment with arsenic trioxide achieves a remission, further courses of this drug may be given. A stem cell transplant may also be an option. If a second remission is not achieved, treatment options may include a stem cell transplant or taking part in a clinical trial.

Additional information related to treatment of acute promyelocytic leukemia can be accessed through Medscape. This includes detailed information related to the use of arsenic trioxide.

APL is not inherited. The condition arises from a translocation in some of the body's cells (somatic cells) that occurs after conception. This is referred to as a somatic mutation. Somatic mutations may affect the individual by causing cancers or other diseases, but they are not passed on to offspring.