Glossary of Terms

The following is a glossary of terms related to bone marrow failure diseases. You can also browse the glossary of drug names.
Click one of the letters above to advance the page to terms beginning with that letter.

A

acute myelogenous leukemia

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(uh-KYOOT my-uh-LAH-juh-nuss loo-KEE-mee-uh) A cancer of the blood cells. It happens when very young white blood cells (blasts) in the bone marrow fail to mature. The blast cells stay in the bone marrow and become to numerous. This slows production of red blood cells and platelets. Some cases of MDS become AML. But most do not. Also called AML, acute myeloblastic leukemia, acute myelocytic leukemia, acute myeloid leukemia.

allogeneic stem cell transplant

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A procedure where bone marrow stem cells are taken from a genetically matched donor (a brother, sister, or unrelated donor) and given to the patient through an intravenous (IV) line. In time, donated stem cells start making new, healthy blood cells.

alternative medicine

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See complementary and alternative medicine.

anaphylaxis

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(an-uh-fuh-LAK-suss) A very severe allergic reaction to a foreign protein, as in a bee sting, or to a medicine. This reaction causes the blood pressure to drop and trouble breathing. Before a patient receives ATG, a treatment for aplastic anemia, a skin test is given to find out if they are likely to develop anaphylaxis. Also known as anaphylactic shock.

androgen therapy

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An approach to treating bone marrow failure using natural male hormones. Androgen therapy can help the bone marrow make more blood cells. This is an older treatment for bone marrow failure that is rarely used because of the side effects. Scientists are studying these medicines to try to better understand why they work in some cases of acquired and genetic bone marrow failure.

anemia

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(uh-NEE-mee-uh) A condition in which there is a shortage of red blood cells in the bloodstream. This causes a low red blood cell count. Symptoms of anemia are fatigue and tiredness.

antibiotic

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(an-tee-by-AH-tik) A medicine that fights bacterial infections. When a person with bone marrow failure does not have enough neutrophils, the white blood cells that fight infection, antibiotics may help to prevent and fight infection.

anticoagulant

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(ant-i-ko-AG-yuh-lunt) See blood thinner.

aplastic anemia

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(ay-PLASS-tik uh-NEE_mee-uh) A rare and serious condition in which the bone marrow fails to make enough blood cells: red blood cells, white blood cells, and platelets. The term aplastic is a Greek word meaning not to form. Anemia is a condition that happens when red blood cell count is low. Most scientists believe that aplastic anemia happens when the immune system attacks the bone marrow stem cells. Aplastic anemia can be acquired (begin any time in life) or can be hereditary (less common, passed down from parent to child).

apoptosis

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Programmed cell death.

ascites

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(uh-SITE-eez) Extra fluid and swelling in the belly area (abdomen). Also called hydroperitoneum.

autoimmune disease

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Any condition that happens when the immune system attacks the body's own normal tissues by mistake.

autologous stem cell transplant

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A procedure in which some of the patient's own bone marrow stem cells are removed, frozen, and then returned to the through an intravenous (IV) line. In time, the stem cells start making new, healthy blood cells.

autosomal dominant

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Describes one of several ways that a trait or disorder can be inherited, or passed down through families. "Autosomal" means that the mutated, or abnormal, gene is located on one of the numbered, or non-sex, chromosomes. "Dominant" means that only one copy of the mutated gene is enough to cause the disease. Dyskeratosis congenita is a rare cause of bone marrow failure disease. It may have an autosomal dominant, autosomal recessive or x-linked pattern of inheritance.

autosomal recessive

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Describes one of several ways that a trait or disorder can be inherited, or passed down through families. "Autosomal" means that the mutated, or abnormal, gene is located on one of the numbered, or non-sex, chromosomes. "Recessive" means that two copies of a mutated gene must be present to cause the disease. Dyskeratosis congenita is a rare cause of bone marrow failure. It may have an autosomal dominant, autosomal recessive or x-linked pattern of inheritance.

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B

basic research

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The study of a subject to increase knowledge and understanding about it. The goal of basic research in medicine is to better understand disease. In the laboratory, basic research scientists study changes in cells and molecules linked to disease. Basic research helps lead to better ways of diagnosing, treating, and preventing disease. Also called basic science research.

basophil

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A type of white blood cell that plays a role in allergic reactions.

benzene

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A chemical that is widely used by the chemical industry in the United States to make plastics, resins, nylon and synthetic fibers. Benzene is found in tobacco smoke, vehicle emissions, and gasoline fumes. Exposure to benzene may increase the risk of developing a bone marrow failure disease. Benzene can affect human health by causing bone marrow stem cells not to work correctly.

bilirubin

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(bil-i-ROO-bun) A reddish yellow substance formed when red blood cells break apart. It is found in the bile and in the blood. Yellowing of the skin and eyes can occur with high levels of bilirubin. Also called total bilirubin.

biologic agent

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A substance made from a living system, such as a virus, and used to prevent or treat disease. Biological drugs include antibodies, globulin, interleukins, serum, and vaccines. Also called a biologic or biological drug.

blast cell

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A young white blood cell. The number of blast cells in the bone marrow helps define how severe MDS is in a person. When 20 out of 100 cells in the bone marrow are blasts, this is considered acute myeloid leukemia.

blasts

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See Blast Cells.

blood clot

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A mass of blood that forms when platelets stick together. Harmful blood clots are more likely to happen in PNH. The term thrombus describes a blood clot that develops and attaches to a blood vessel. The term embolus describes a blood clot or other foreign matter that gets into the bloodstream and gets stuck in a blood vessel.

blood thinner

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A medicine used to stop blood clots from forming. Blood thinners can be used to treat or prevent clots. Some common blood thinners are enoxaprin (Lovenox), heparin (Calciparine or Liquaemin), and warfarin (Coumadin). Also called and anticoagulant or thrombopoiesis inhibitor.

blood transfusion

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A procedure in which whole blood or one of its components is given to a person through an intravenous (IV) line into the bloodstream. A red blood cell transfusion or a platelet transfuson can help some patients with low blood counts.

bone marrow

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The soft, spongy tissue inside most bones. Blood cells are formed in the bone marrow.

bone marrow aspiration

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A medical procedure to remove of a small amount of liquid bone marrow through a needle inserted into the back of the hip. The liquid bone marrow is examined for abnormalities in cell size, shape, or look. Tests may also be run on the bone marrow cells to look for any genetic abnormalities.

bone marrow biopsy

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A medical procedure to remove a small piece of solid bone marrow using a needle that goes into the marrow of the hip bone. The solid bone marrow is examined for cell abnormalities, the number of different cells and checked for scaring of the bone marrow.

bone marrow failure

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A condition that occurs when the bone marrow stops making enough healthy blood cells. The most common of these rare diseases are aplastic anemia, myelodysplastic syndromes (MDS) and paroxysmal nocturnal hemoglobinuria (PNH). Bone marrow failure can be acquired (begin any time in life) or can be hereditary (less common, passed down from parent to child).

bone marrow transplant

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A procedure where bone marrow stem cells are collected from marrow inside the donor's hipbone and given to the patient through an intravenous (IV) line. In time, donated stem cells start making new, healthy blood cells.

Budd-Chiari syndrome

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(bud-kee-AR-ee SIN-drome) A blood clot in the major vein that leaves the liver (hepatic vein). The liver and the spleen may become enlarged. Budd-Chiari syndrome can occur in PNH.

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C

cellularity

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How much of the bone marrow volume is occupied by various types of blood cells.

chemotherapy

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(kee-moe-THER-uh-pee) The use of medicines that kill cells (cytotoxic agents). People with high-risk or intermediate-2 risk myelodysplastic syndrome (MDS) may be given chemotherapy to kill bone marrow cells that have an abnormal size, shape, or look. Chemotherapy hurts healthy cells along with abnormal cells. If chemotherapy works in controlling abnormal cells, then relatively normal blood cells will start to grow again. Low-dose chemotherapy agents include: cytarabine (Ara-C) and hydroxyurea (Hydrea). High-dose chemotherapy agents include: daunorubicin (Cerubidine), idarubicin (Idamycin), and mitoxanrone (Novantrone).

chromosomes

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The part of the cell that contains our DNA or genetic code.

chronic illness

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A medical condition that lasts a long time. A chronic illness can affect a person's lifestyle, ability to work, physical abilities and independence.

chronic illness counselor

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A person who gives advice, or counsel, to people who are coping with long-term illness. A chronic illness counselor helps people understand their abilities and limitations, cope with the stress, pain, and fatigue associated with long-term illness. A chronic illness counselor can often be located by contacting a local hospital.

clinical research

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A type of research that involves individual persons or a group of people. There are three types of clinical research. Patient-oriented research includes clinical trials which test how a drug, medical device, or treatment approach works in people. Epidemiology or behavioral studies look at the patterns and causes of disease in groups of people. Outcomes and health services research seeks to find the most effective treatments and health services.

clinical trial

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A type of research study that tests how a drug, medical device, or treatment approach works in people. There are several types of clinical trials. Treatment trials test new treatment options. Diagnostic trials test new ways to diagnose a disease. Screening trials test the best way to detect a disease or health problem. Quality of life (supportive care) trials study ways to improve the comfort of people with chronic illness. Prevention trials look for better ways to prevent disease in people who have never had the disease.

Trials are in four phases: Phase I tests a new drug or treatment in a small group to see if it is safe. Phase II expands the study to a larger group of people to find out if it works. Phase III expands the study to an even larger group of people to compare it to the standard treatment for the disease; and Phase IV takes place after the drug or treatment has been licensed and marketed to find out the long-term impact of the new treatment.

clone

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To make copies. Bone marrow stem cells clone themselves all the time. The cloned stem cells eventually become mature blood cells that leave the bone marrow and enter the bloodstream.

coagulate

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To thicken. Normal blood platelets cause the blood to coagulate and stop bleeding.

complement system

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A group of proteins that move freely in the bloodstream. These proteins support (complement) the work of white blood cells by fighting infections.

complementary and alternative medicine

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A medical approach that is not currently part of standard practice. Complementary medicine is used along with standard medicine. Alternative medicine is used in place of standard medicine. Example of CAM therapies are acupuncture, chiropractic, homeopathic, and herbal medicines. There is no complementary or alternative therapy that effectively treats bone marrow failure. Some CAM therapies may even hinder the effectiveness of standard medical care. <strong>Patients should talk with their doctor if they are currently using or considering using a complementary or alternative therapy.</strong>

complete blood count (CBC)

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A group of tests performed on a small amount of blood. The CBC measures the number of each blood cell type, the size of the red blood cells, the total amount of hemoglobin, and the fraction of the blood made up of red blood cells. Also called a CBC.

cord blood transplant

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A procedure where umbillical cord stem cells are given to the patient through an intravenous (IV) line. Stem cells are collected from an umbilical cord right after the birth of a baby. They are kept frozen until needed. In time, donated stem cells given to the patient begin making new, healthy blood cells.

CT scan

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An imaging technique using x-ray technology and computerization to create a three-dimentional image of a body part. Also called a CT scan, it can be used to locate a blood clot in the body.

cytogenetic remission

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A response to treatment indicating that no sign of abnormal chromosomes are found. When a test is done on a patient with 5q deletion MDS, and there are no signs of an abnormal chromosome 5, then that patient has achieved a cytogenetic remission. Also called cytegenetic response.

cytogenetics

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(sie-toe-juh-NEH-tiks) The study of chromosomes (DNA), the part of the cell that contains genetic information. Some cytogenetic abnormalities are linked to different forms of myelodysplastic syndromes (MDS).

cytopenia

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(sie-tuh-PEE-nee-uh) A shortage of one or more blood cell types. Also called a low blood count.

cytotoxic agent

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(sie-tuh-TOK-sik) A medicine that kills certain cells. Chemotherapy for MDS patients often involves the use of cytotoxic agents.

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D

d-dimer

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A test that helps doctors find out if a person has a problem with blood clotting.

de novo

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(di-NO-vo) Brand new, referring to the first time something occurs. MDS that is untreated or that has no known cause is called de novo MDS.

dead bowel

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The death of part of the intestine. This can happen if the blood supply in the intestine is cut off, for example, from a blood clot in the abdomen. Also called intestinal necrosis, ischemic bowel, dead gut.

Diamond-Blackfan Anemia

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A rare form of pure red cell aplasia that can be passed down from parent to child. Diamond-Blackfan anemia (DBA) is characterized by low red blood cell counts detected in the first year of life. Some people with DBA have physical abnormalities such as small head size, low frontal hairline, wide-set eyes, low-set ears. Genetic testing is used to diagnose DBA.

dietary supplement

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Vitamins, minerals, herbs and other substances meant to improve your nutritional intake. Dietary supplements are taken by mouth in the form of a pill, capsule, tablet or liquid.

differentiate

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To become distinct or specialized. In the bone marrow, young parent cells (stem cells) develop, or differentiate, into specific types of blood cells (red cells, white cells, platelets).

dominant gene

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The gene that always expresses itself over a recessive gene. A person with a dominant gene for a disease has the symptoms of the disease. They can pass the disease on to children.

Dyskeratosis Congenita

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An inherited disease that may lead to bone marrow failure.

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E

engraftment

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Refers to how well a graft (donor cells) is accepted by the host (the patient) after a bone marrow or stem cell transplant. Several factors contribute to better engraftment: physical condition of the patient, how severe the disease is, type of donor available, age of patient. Successful engraftment results in new bone marrow that produces healthy blood cells.

eosinophil

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A type of white blood cell that kills parasites and plays a role in allergic reactions.

epidemiology

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The study of patterns and causes of disease in groups of people. Epidemiology researchers study how many people have a disease, how many new cases are diagnosed each year, where patients are located, and environmental or other factors that influence disease.

erythrocyte

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(i-RITH-ruh-site) See red blood cell.

erythropoietin

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(i-rith-row-POY-uh-tun) A protein made by the kidneys. Erythropoietin, also called EPO, is created in response to low oxygen levels in the body (anemia). EPO causes the bone marrow to make more red blood cells. A shortage of EPO can also cause anemia.

erythropoietin-stimulating agent (ESA)

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A medicine used to help the bone marrow make more red blood cells. Epoetin alfa (Epogen, Procrit) and darbepoetin alfa (Aranesp) are erythropoietin-stimulating agents that can help boost the red blood cell count of some bone marrow failure patients. Also called red blood cell growth factor.

estradiol

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A form of estrogen, it is the most potent female hormone. It is also present in males. Estradiol is involved in many body functions beyond the reproductive system. Researchers are investigating the role of estradiol in the treatment of genetic bone marrow failure.

etiology

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The cause or origin of a disease.

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F

FAB Classification System

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A criteria used for classifying different types of myelodysplastic syndromes (MDS). The FAB (French, American, British) Classification System was developed by a group of French, American and British scientists. This system is based on 2 main factors: the percentage of blast cells in bone marrow, and the percentage of blast cells in the bloodstream. The FAB system is somewhat outdated, but is still used by some doctors today. The World Health Organization (WHO) Classification System has largely replaced the FAB Classification System.

Fanconi anemia

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A rare inherited disorder that happens when the bone marrow does not make enough blood cells: red cells, white cells, and platelets. Fanconi anemia is diagnosed early in life. People with Fanconi anemia have a high likelihood of developing cancer. Genetic testing is used to diagnose Fanconi anemia.

ferritin

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(FER-i-tin) A protein inside of cells that stores iron for later use by your body. Sometimes ferritin is released into the blood. The ferritin level in the blood is called serum ferritin.

ferritin test

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(FER-i-tin) A blood test used to monitor how much iron the body is storing for later use.

fibrosis

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(fie-BRO-suss) Scarring of tissue. Fibrosis of the bone marrow is an feature seen in some types of unclassified myeldysplastic syndrome (MDS).

FISH

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See fluorescence in situ hybridization.

flow cytometry

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(sy-TOM-uh-tree) A laboratory test that gives information about cells, such as size, shape, and percentage of live cells. Flow cytometry is the test doctors use to see if there are any proteins missing from the surface of blood cells. It is the standard test for confirming a diagnosis of paroxysmal nocturnal hemoglobinuria (PNH).

fluorescence in situ hybridization

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(flor-EH-sense in SIT-tyoo hy-bru-duh-ZAY-shun) An important laboratory test used to help doctors look for chromosomal abnormalities and other genetic mutations. Fluorescence in situ hybridization, also called FISH, directs colored light under a microscope at parts of chromosomes or genes. Missing or rearranged chromosomes are identified using FISH.

folate

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(FOE-late) A B-vitamin that is found in fresh or lightly cooked green vegetables. It helps the bone marrow make normal blood cells. Most people get enough folate in their diet. Doctors may have people with paroxysmal nocturnal hemaglobinuria (PNH) take a man-made form of folate called folic acid.

folic acid

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See folate.

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G

graft-versus-host disease (GVHD)

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Also called GVHD, it is a common complication of bone marrow/stem cell transplantation. It is caused when the donor's immune cells, now in the patient, begin to see the the patient's body as foreign and mount an immune response. GVHD most commonly effects the recipient's skin, intestines, or liver. Severity can range from mild to very severe. In some cases, GVHD can be prevented or treated with immunosuppressive drug therapy.

granulocyte

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Any one of these three types of white blood cells: neutrophils, eosinophils, and basophils. These cells have granules that contain enzymes to help fight infection.

growth factor

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A substance made by the body that stimulates the bone marrow to produce blood cells. Some growth factors are man-made in the laboratory and used for treating low blood counts. These include red blood cell growth factors called erythropoietin (EPO) and darbepoetin, and white blood cell growth factors called granulocyte colony stimulating factors (GCSF) and granulocyte macrophage colony stimulating factors (GMCSF). Also called cytokines.

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H

Ham Test

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A laboratory test that looks at the whether red blood cells break apart too easily when they are placed in mild acid. This test has been used in the past to diagnose paroxysmal nocturnal hemoglobinuria (PNH). Most doctors now use flow cytometry, a more accurate method of testing for PNH. Ham Test is also called acid hemolysin test.

hematocrit

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(hi-MA-tuh-crit) A blood test that measures the percentage of the blood made up of red blood cells. This measurement depends on the number of red blood cells and their size. Hematocrit is part of a complete blood count. Also called HCT, packed cell volume, PCV.

hematologist

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(hee-muh-TOL-uh-jist) A doctor who specializes in treating blood diseases and disorders of blood producing organs.

hematopoiesis

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(hi-mat-uh-poy-EE-suss) The process of making blood cells in the bone marrow.

hemochromatosis

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A condition that occurs when the body absorbs and stores too much iron. This leads to a condition called iron overload. In the United States, hemochromatosis is usually caused by a genetic disorder. Organ damage can occur if iron overload is not treated.

hemoglobin

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A protein in the red blood cells. Hemoglobin picks up oxygen in the lungs and brings it to cells in all parts of the body.

hemoglobinuria

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(hee-muh-gloe-buh-NYOOR-ee-uh) The presence of hemoglobin in the urine.

hemolysis

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(hi-MOL-uh-suss) The destruction of red blood cells.

HLA

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See human leukocyte antigen.

hormone

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A part of the endocrine system that serves as the body's chemical messengers. Hormones move through the bloodstream to transfer information and instruction from one set of cells to another.

human leukocyte antigen

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(LEW-kuh-site ANT-i-jun) One of a group of proteins found on the surface of white blood cells and other cells. These antigens differ from person to person. A human leukocyte antigen test is done before a stem cell transplant to closely match a donor and a recipient. Also called HLA.

hypercellular

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A condition in which there are too many cells, for example, within the bone marrow. Patients with leukemia have hypercellular bone marrow filled with to many immature white blood cells.

hypocellular

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A condition in which there are too few cells, for example, within the bone marrow. Patients with aplastic anemia have hypocellular bone marrow.

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I

idiopathic

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Usually refers to any condition with no known cause.

immunocompromised

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(i-myoo-no-KOM-pruh-mized) Occurs when the immune system is not functioning properly, leaving the patient open to infection. A person can be immunocompromised due to low white blood cell count or due to some medicines. Also called immune compromised.

immunosuppressive drug therapy

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(i-myoo-no-suh-PREH-siv) Drugs that lower the body's immune response and allow the bone marrow stem cells to grow and make new blood cells. ATG (antithymocyte globulin) or ALG (antilymphocyte globulin) with cyclosporine are used to treat bone marrow failure in aplastic anemia. Immunosuppressive drugs may help some patients with myelodysplastic syndromes (MDS) and paroxysmal nocturnal hemoglobinuria (PNH).

Institutional Review Board

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A committee that makes sure a clinical trial is safe for patients in the study. Each medical center, hospital, or research facility doing clinical trials must have an active Institutional Review Board (IRB). Each IRB is made up of a diverse group of doctors, faculty, staff and students at a specific institution.

International Prognostic Scoring System

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A system that turns patient data into a score. The score tells how quickly a myelodysplastic syndrome (MDS) case is progressing and helps predict what may happen with the patient's MDS in the future. Also called IPSS.

intravenous infusion

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A method of getting fluids or medicines directly into the bloodstream over a period of time. Also called IV infusion.

investigational new drug

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A new drug, antibiotic drug, or biological drug that is used in a clinical trial. It also includes a biological product used in the laboratory for diagnostic purposes. Also called IND.

iron chelation therapy

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(kee-LAY-shun) A drug therapy to remove extra iron from the body. Patients with high blood iron (ferritin) levels may receive iron chelation therapy. The U.S. Food and Drug Administratin (FDA) has approved two iron chelators to treat iron overload in the U.S.: deferasirox, an oral iron chelator, and deferoxamine, a liquid given by injection.

iron overload

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A condition that occurs when too much iron accumulates in the body. Bone marrow failure disease patients who need regular red blood cell transfusions are at risk for iron overload. Organ damage can occur if iron overload is not treated.

ischemia

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(iss-KEE-mee-uh) Occurs when the blood supply to specific organ or part of the body is cut off, causing a localized lack of oxygen.

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L

lactate dehydrogenase

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(LAK-tate dee-high-DROJ-uh-nase) An enzyme found in the blood and in many of the body's organs. High levels of LDH in the blood can mean that red blood cells are breaking apart (hemolysis) or that there is tissue damage in the body. It is important for patients with paroxysmal nocturnal hemoglobinuria (PNH) to have their LDH monitored regularly. Also called lactic dehydrogenase, LDH.

leukocyte

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(LEW-kuh-site) See white blood cell.

low molecular weight heparin (LMWH)

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A blood thinner, or anticoagulant, that comes in two forms. Both can be injected underneath the skin, subcutaneously. Heparin comes in high (standard unfractionated heparin) or low (fractionated heparin) molecular weights. LMWH might be prescribed for PNH patients at risk for blood clots.

lymphatic system

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A network of organs, lymph nodes, lymph ducts, and lymph vessels that help keep the body's fluids in balance and help the body fight infection.

lymphocyte

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A type of white blood cell. B lymphoctyes, or B cells, help make special proteins called antibodies that fight bacteria and viruses (immune response). T lymphocytes, or T cells, help kill tumor cells and help the body's immune response.

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M

magnetic resonance imaging

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An Imaging technique that uses a large donut-shaped magnet and radio waves to look at the organs of the body. A doctor may order a this procedure, also called an MRI, to find a blood clot. MRI does not use radiation.

matched related donor

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A bone marrow/stem cell donor that is a sibling or another family relation to the patient.

mean corpuscular volume

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A measurement of the average size of a person's red blood cells. If the mean corpuscular volume is high, the red blood cells are larger than normal (macrocytic). If the mean corpuscular volume is low, the red blood cells are smaller than normal (microcytic). Also called MCV.

megakaryocyte

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A large bone marrow cell that makes platelets, necessary for normal blood clotting.

mini transplant (aka reduced intensity transplant)

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A procedure similar to standard bone marrow transplant. The mini transplant uses a mild form of chemotherapy pre-treatment. This reduces side effects caused by chemotherapy, making it more tolerable to older adults. It does not reduce the risk of graft-versus-host disease. Also called nonmyeloablative transplant.

monoclonal antibody

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A type of protein called an antibody that is engineered to look for a specific substance in the body. There are many kinds of monocloncal antibodies. Each one looks for only one substance. Eculizumab (Soliris) is an monoclonal antibody that may be prescribed to treat patients with paroxysmal nocturnal hemoglobinuria (PNH).

monocyte

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A large white blood cell. Monocytes move through the blood to the tissues where they become macrophages. Macrophages are immune cells that surround and kill germs such as bacteria and viruses.

monosomy 7

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Describes the loss of one of the two number 7 chromosomes. "Mono" means one and "somy" comes from the word chromosome. A laboratory test called fluorescence in situ hybridization (FISH) detects monosomy 7 and other genetic abnormalities. Monosomy 7 can occur in adult patients with MDS and can occur in childhood bone marrow failure.

morphology

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The study of the structure and form of an organism or one of its parts.

mutation

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Any change or alteration in a gene. A mutation may cause disease or may be a normal variation. Paroxysmal nocturnal hemoglobinuria (PNH) occurs because of a mutation in the PIG-A gene of a single stem cell in the bone marrow.

myelodysplastic syndromes

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(my-eh-lo-diss-PLASS-tik SIN-dromez) A group of disorders where the bone marrow does not work well, and the bone marrow cells fail to make enough healthy blood cells. Myelo refers to the bone marrow. Dysplastic means abnormal growth or development. People with MDS have low blood cell count for at least 1 blood cell type. Also, the bone marrow and blood contain blood cells with an abnormal shape, size, or look. Symptoms vary greatly from person to person. The differences depend on which blood cells are affected.

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N

natural killer cells

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a type of cell that lacks B-cell and T-cell receptors and attacks mutant and virus-infected cells

neutropenia

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(noo-truh-PEE-nee-uh) A condition in which there is a shortage of neutrophils in the bloodstream. Neutrophils are a type of white blood cell. This results in a low white blood cell count.

neutropenic diet

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(noo-truh-PEE-nik) A diet for a patient with very low white blood cell count. A neutropenic diet avoids the use of certain foods that can may contain germs, such as raw meats, aged cheeses, fermented drinks, and unwashed fruits and vegetables.

neutrophil

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(NOO-truh-fil) The most numerous of the white blood cells, important for helping the body fight infections (particularly bacterial and fungal infections.

nitric oxide

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(NIGH-trik OK-side) A molecule that helps muscles stay smooth and relaxed. A shortage of nitric oxide can occur in paroxysmal nocturnal hemoglobinuria (PNH), causing muscle spasms in certain parts of the body.

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O

off label drug

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An approved medicine that is prescribed by a licensed doctor for a purpose other than that for which is was approved by the U.S. Food and Drug Administration (FDA).

oncologist

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(on-KAH-luh-jist) A doctor who specializes in the treatment and prevention of cancer.

orphan drug

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A drug or biologic agent that treats a rare disease or condition. A disease is considered rare if fewer than 200,000 people in the United States have it.

over-the-counter medicine

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A medicine that is available without a prescription from the doctor. Also called OTC medicine.

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P

pancytopenia

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A shortage of all types of blood cells - red blood cells, white blood cells, and platelets.

paroxysmal nocturnal hemoglobinuria

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(par-uk-SIZ-muhl nok-TURN-uhl hee-muh-gloe-buh-NYOOR-ee-uh) A rare and serious blood disease that causes red blood cells to break apart. Paroxysmal means sudden and irregular. Nocturnal means at night. Hemoglobinuria means hemoglobin in the urine. Hemoglobin is the red part of red blood cells. A person with PNH may have episodes of dark urine in the morning, but this symptom is not present in all PNH patients.

pathophysiology

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Functional changes in the bodies that are associated with or result from disease or injury.

peripheral blood stem cell transplant

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A procedure where stem cells are collected from the donor's circulating (peripheral) blood. These stem cells are then given to the patient through an intravenous (IV) line. In time, donated stem cells start making new, healthy blood cells. Also called PBSC transplant.

petechiae

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(puh-TEE-kee-ie) Small, flat red or purplish spots on the skin, caused by bleeding. It is often a symptom of a low platelet count.

phagocyte

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A type of white blood cell that surrounds and kills microorganisms, such as bacteria and fungi. They also remove dead cells. Monocytes, macrophages, and neutrophils are phagocytes.

pharmacist

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A highly trained and licensed professional whose job concerns the preparation, distribution, and use of prescription drugs. A pharmacist also advises patients, as well as physicians and other health practitioners, on the selection, dosages, interactions, and side effects of medications.

PIG-A gene

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The gene that is in charge of making a protective shield of proteins on normal red blood cells. Paroxysmal nocturnal hemoglobinuria (PNH) occurs because of a change (mutation) in the PIG-A gene of a single stem cell in the bone marrow.

placebo

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A placebo is an inactive pill, liquid, or powder that has no treatment value.

plasma

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The fluid part of the blood. Plasma is mostly made of water with chemicals in it. These chemicals include proteins, hormones, minerals, and vitamins.

platelet

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The smallest type of blood cell. Platelets help the blood to clot and stop bleeding. Also called a thrombocyte.

platelet transfusion

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A procedure in which platelets are given to a person through an intravenous (IV) line into the bloodstream. Platelets are more likely than red blood cells to cause an immune response, such as chills and fever. The use of platelets from one donor (apheresis) reduces the chance of reaction to transfused platelets. Transfused platelets increase blood count and help control bruising and bleeding.

prednisone

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A corticosteroid, a man-made version of a hormone produced naturally by the adrenal gland. It is prescribed when the body is not producing enough of this chemical on its own. Prednisone may be prescribed for numerous reasons. It is sometimes prescribed after an ATG treatment to counteract the effects of serum sickness. It helps by reducing the antibody production of the immune system. Prednisone is sold under a number of different brand names.

prophylactic

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Something that prevents or protects. Blood thinners may be given as a prophylactic to prevent blood clots in high risk patients.

protocol

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An action plan that describes what will be done in a clinical trial and how it will be carried out. This plan is reviewed and approved by a committee at each place doing the clinical trial. This committee is known as the Institutional Review Board.

pulmonary embolism

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(PULL-muh-nerr-ee EM-buh-liz-um) A blockage of an artery that carries blood to the lungs. See Embolism.

pure red cell aplasia (PRCA)

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A condition that occurs when the bone marrow stem cells do not make red blood cells. Red blood cell counts are low. White blood cell and platelet counts are normal.

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R

recessive gene

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The gene that does not express itself when a dominant gene is present. A person with a recessive gene for a disease does not have the symptoms of the disease, but can pass the disease on to children. If a person inherits a recessive gene for a disease from both parents, they may get the disease.

red blood cell

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The most numerous type of blood cell in healthy people. Red blood cells contain hemoglobin, a protein that picks up oxygen in the lungs and brings it to cells in all parts of the body. Also called erythrocyte, RBC.

red blood cell growth factor

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See erythropoietin-stimulating agent.

red blood cell transfusion

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A procedure in which packed red blood cells are given to a person through an intravenous (IV) line into the bloodstream. Transfused red blood cells increase the blood count and help improve symptoms of anemia. Before transfused blood is given, donated blood is typed and crossmatched to the recipients blood. Also called RBC transfusion.

reduced intensity transplant

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A procedure similar to standard bone marrow transplant. The mini transplant uses a mild form of chemotherapy pre-treatment. This reduces side effects caused by chemotherapy, making it more tolerable to older adults. It does not reduce the risk of graft-versus-host disease. Also called nonmyeloablative transplant.

Synonyms: nonmyeloablative transplant

refractory

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Not responsive to treatment or cure. For example, refractory anemia is a low red blood cell count that doesn't respond to standard treatments.

reticulocyte

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An immature red blood cell. Reticulocytes are normally found in the bone marrow. They are present in the bloodstream only in very low numbers.

ribosomal protein gene

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Genes that give instructions for making ribosomal proteins (r-proteins). These proteins are components of cellular structures called ribosomes, which process the cell's genetic instructions to create proteins. Diamond Blackfan anemia is an inherited form of bone marrow failure disease that is caused by mutations in the ribosomal protein genes.

ring sideroblast

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(SID-uh-ruh-blast) A red blood cell that has too much iron. The iron typically forms a ring around the cell's nucleus.

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S

secondary MDS

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A type of MDS that is caused by a previous treatment foranother another disorder or disease. Treatments typically associated with secondary MDS include radiation therapy and chemotherapy used to treat cancer. Also called therapy-related MDS, T-MDS.

serum sickness

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An immune system reaction to foreign proteins in certain medicines. Serum sickness can be a side effect of ATG, causing fever, rash, joint pain, and muscle aches.

Shwachman-Diamond syndrome

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A rare inherited disease that affects many organs, especially the bone marrow, pancreas, and skeletal system. The bone marrow fails to make one or all of the blood cells: red cells, white cells, and platelets. Schwachman-Diamond syndrome is diagnosed with genetic testing.

social worker

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A licensed professional trained to help people manage their daily lives, understand and adapt to changes in health and lifestyle. A social worker also will help people find appropriate community resources, healthcare, legal resources, and government assistance.

spasm

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A sudden, tightening or cramping of a muscle or group of muscles. Spasms in the esophagus (i-SOF-uh-gus) can occur with PNH. The esophagus connects the mouth to the stomach.

stem cell transplant

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A procedure where blood-forming (hemapoietic) stem cells are taken from a healthy donor. They enter the patient's bloodstream through an intravenous (IV) needle and make their way into the bone marrow. The donor cells are called a graft. There are three sources of stem cells: bone marrow, cord blood, and circulating (peripheral) blood.

stem cells

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Cells in the body that develop into other cells. There are two main sources of stem cells. Embryonic stem cells come from human embryos and are used in medical research. Adult stem cells in the body repair and maintain the organ or tissue in which they are found. Blood-forming (hemapoietic) stem cells are found in the bone marrow. These cells make copies of themselves and develop into red cells, white cells, and platelets.

subcutaneous injection

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(sub-kyoo-TAY-nee-uss) A method of giving medicine under the skin using a short needle. Also called a shot.

supplement

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see dietary supplement

supportive care

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Care given to improve the quality of life, or comfort, of a person with a chronic illness. Supportive care treats the symptoms rather than the underlying cause of a disease. The goal is to help the patient feel better. Patients with low blood counts may be given blood transfusions as supportive care to help manage the symptoms of their disease. Also called palliative care, symptom management.

Surveillance, Epidemiology, and End Results Program

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A program of the Centers for Disease Control and Prevention (CDC) and the National Cancer Institute (NCI) to collect data on all forms of cancer, including myelodysplastic syndromes (MDS). In 2001, SEER began collecting data on the incidence and survival of people with MDS. Incidence refers to the number of new cases diagnosed each year.

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T

T cell

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see lymphocyte

T lymphocyte

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see lymphocyte

telomere

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A telomere is the end of a chromosome. Telomeres are made of repetitive sequences of non-coding DNA that protect the chromosome from damage. Each time a cell divides, the telomeres become shorter. EVvntually, the telomeres become so short that the cell can no longer divide.

therapy-related MDS

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see secondary MDS

thrombocyte

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(THROM-buh-site) See platelet.

thrombocytopenia

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(throm-buh-sie-tuh-PEE-nee-uh) A condition in which there is a shortage of platelets in the bloodstream. This results in a low platelet count. Bleeding and bruising often occur with thrombocytopenia.

thrombosis

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(throm-BOE-suss) A blood clot (thrombus) that develops and attaches to a blood vessel.

tissue plasmogenic activator

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An enzyme (protein) that helps break up blood clots, especially when used as soon as possible after the clot forms. Also called tPA.

TLK-199

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TLK-199 is a small molecule drug that stimulates the bone marrow to produce blood cells. Currently TLK-199 is in Phase II of the Food and Drug Administration's (FDA's) clinical trial for the treatment of myelodsyplasitc syndromes (MDS).

transferrin

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A protein that carries iron through the blood and to the organs where it is stored.

transfusion independence

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No longer needing any type of blood transfusion.

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U

unrelated donor

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A donor that is not a sibling or other familial relation of the patient (recipient).

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V

Vitamin B12

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A complex vitamin found in animal products. Vitamin B12 helps maintain healthy red blood cells and nerve cells. A shortage of Vitamin B12 and folate can reduce blood cell production in the bone marrow. Also called B complex vitamin.

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W

white blood cell

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Cells in the body that fight disease and infection by attacking and killing germs. There are several types of white blood cells including neutrophils, eosinophils, basophils, lymphocytes and monocytes. Each type of cell fights a different kind of germ. Also called WBC, leukocyte.

WHO Classification System

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The most current system for classifying leukemia and myelodysplastic syndromes (MDS), it was developed by the World Health Organization (WHO). This system is based on patient data from around the world and on the most up-to-date knowledge of MDS. WHO Classification consists of 6 subtypes based on tests of the blood and bone marrow.

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