This is one of the subtypes of acute myeloid leukemia (AML), a cancer of the blood-forming tissue. In the bone marrow, the hematopoietic stem cells produce the red blood cells, white blood cells and platelets. In the Acute Promyelocytic leukemia (APML), an immature type of white blood cells called promyelocytes can grow in excess resulting in the low quantity of normal white blood cells and with the reduced production of other types of blood cells. This can cause various associated symptoms and increases the risk of developing frequent infections and bleeding. APML is one of the frequently cured forms of AML subtypes where it is estimated that around 85-90% of the children treated for this cancer are considered to be cured.
Causes
The mutation in the PML and RARA gene causes the APML. This is the translocation between chromosome that joins part of PML gene with the RARA gene and the production of the protein from this is known as PML-RARa. The protein that is produced from these genes is involved in the regulation of gene transcription. The protein produced by the PML gene functions as the tumor suppressor. The genetic problem affects the normal function of these essential proteins and as the result, the blood cells proliferate abnormally. The genetic fusion of PML-RARA gene accounts for most of the cases although few cases have been identified that involves RARA and other genes.
Symptoms
The symptoms of APML develop as the result of reduced white blood cells, low red blood cells, low platelets and abnormal clotting factors. The symptoms include easy bleeding, fever, frequent infections, low red blood cell count, fatigue, bleeding of the gums, easy bruising, the presence of blood in the urine, paleness from anemia, poor appetite and weight loss. The leukemia cells can also spread to other parts of the body such as the bones and joints causing pain. This cancer is most commonly diagnosed among individuals among the age of 40 although it can develop at any age.
Diagnosis
The diagnosis of APML is possible with the bone marrow aspiration or biopsy that removes the sample of the fluid and the marrow cells for analysis. The test that determines the PML/RARA gene fusion can also confirm the diagnosis.
Treatment
Among the individuals identified with the PML/RARA gene fusion, the treatment includes the all trans retinoic acid (ATRA) which is similar to vitamin A, that is initiated soon after the diagnosis. The administration of ATRA enables the promyelocytes to develop and die as they normally do. As retinoic acid syndrome can develop among some of the patients after the treatment, these cases will be monitored for breathing problems. During the consolidation phase, a medication known as arsenic trioxide and chemotherapy are together used as the treatment for the affected individual. This process ensures that the inactive cells are also destroyed which can otherwise relapse.
References
https://ghr.nlm.nih.gov/condition/acute-promyelocytic-leukemia#inheritance
https://www.cancer.org/cancer/acute-myeloid-leukemia/treating/m3-leukemia.html
https://www.stjude.org/disease/acute-promyelocytic-leukemia.html
