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Leukemia (leukaemia in Commonwealth English) is a cancer of the blood or bone marrow characterized by an abnormal proliferation of blood cells, usually white blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms. Each year, some 29,000 adults and 2,000 children are diagnosed living with any type of cancer especially leukemia, a form of cancer that is caused by the abnormal production of white blood cells in the bone marrow. Current treatments rely primarily on killing the cancer cells, which also destroys normal cells. But what if a way could be found to reprogram cancerous cells back into normal cells? To understand how white blood cells are produced, one must begin by looking at the genetic code, the DNA, which provides the blueprint for all the life processes that are carried out in cells throughout the body. All of the cells in the body begin as stem cells with the same DNA. If stretched out in one continuous strand, this genetic blueprint would be about two meters long (about six feet), yet cells somehow manage to compact this rather long DNA strand into its nucleus without tangling or disrupting the exact DNA sequence.
Acute promyelocytic leukemia (APL) is characterized by an excess of immature and malignant cells. This rare form of leukemia is the consequence of a chromosome translocation, uniquely found in leukemic cells. This chromosomal anomaly leads to the production of a fusion protein known as PML-RAR. Stemming from PML(1) and RAR(2) genes, this fusion protein is at the root of the pathology. It blocks the differentiation of promyelocytes, which remain immature. Incapable of disappearing naturally, the malignant cells accumulate in the bone marrow and in the blood. At the moment there are two agents that are particularly effective for treating APL: a hormone, retinoic acid, and a poison, arsenic oxide. In use for a number of years altready, they bring about remission in patients. Until now, this success has been explained by the fact that these drugs induced differentiation of the malignant cells into normal differentiated cells, which end up dying, which results in the normalization of the condition of the bone marrow.
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