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DNA: The abbreviation for deoxyribonucleic acid. This nucleic acid provides the mechanism for storing genetic information. There are four different chemical components of DNA called bases that are arranged in various sequences. The four bases are abbreviated C, A, T, and G. Long sequences of these four bases form a gene and the base sequence carries the code that determines the protein that will be made as a result of the action of that gene. The genes determine an individual's inherited characteristics.

Deletion: A chromosome abnormality in which part or all of a single chromosome has been lost.

Depletion: A laboratory procedure for reducing the numbers of a specific cell type within bone marrow donated for transplantation. One example is T lymphocyte depletion or removal. It is done to minimize immune reactivity of donor cells. This step may be used to decrease the likelihood or severity of graft versus host disease in circumstances in which donor-recipient matching is imperfect (particularly in relation to unrelated donor transplants).

Differentiation: The process by which stem cells transform from cells without a specific structural or functional characteristics into functional cells of a single blood cell line. The process of differentiation of stem cells forms the red blood cells, platelets, neutrophils, monocytes, eosinophils, basophils and lymphocytes.

Disease-Free Survival: The proportion of patients in complete remission who have had no recurrence of disease during the time period under study (e.g., one year, five years, ten years, etc.)

Disseminated Disease: Disease in which the lymphoma cells have spread from the lymph nodes or site of origin to other lymph nodes or organs. Leukemia and myeloma are widespread in the marrow of bones in virtually all cases at the time of diagnosis. Rare cases of leukemia and occasional cases of myeloma may begin with a localized are of disease.

Diuretic: A drug to promote the excretion of urine. May be used during chemotherapy to dilute the uric acid in the urine. Uric acid is a product of cell destruction that can precipitate in the kidney or urinary tract forming stones.

Donor Lymphocyte Infusion: If a patient who has had an allogeneic bone marrow transplant has a relapse, with return of the original disease, they may be given lymphocytes from the original stem cell donor. This may induce an immune reaction against the leukemic cells. This therapy has been most effective in patients with chronic myelogenous leukemia who relapse after transplantation.