Anemia: Decrease in the oxygen-carrying capacity of the blood; indicated by a low hematocrit (Hct) and hemoglobin (Hb) concentration.

Anomaly: Deviation from what is regarded as normal; congenital malformation; birth defect

Apoptosis: a form of programmed cell death where cells are eliminated without releasing potential harmful compounds into their surroundings. Apoptosis differs from necrosis, a form of cell death often accompanied by the release of toxins into the environment and subsequent inflammation

B Cells: Type of lymphocyte involved in the production of antibodies.

Basophil: Type of white blood cell that contains and releases histamine from intracellular granules; a type of granulocyte involved in allergic reactions; normal value: 0.5-2% or 25-100 per microliter.

Bone Marrow: Soft tissue within the bones where blood cells are manufactured.

Bone Marrow Aspiration: Test in which a sample of bone marrow cells is removed from the bone marrow with a needle and examined under a microscope.

Bone Marrow Transplant (BMT): Procedure during which bone marrow cells of the patient are destroyed by chemotherapy and/or radiation and then replaced with healthy hematopoietic stem cells from a donor. Stem cells capable of repopulating the bone marrow during a transplant may also be obtained from peripheral blood or umbilical cord blood of a donor.

Chelation: A therapy used to remove excess iron from the blood and tissues by providing drugs to which iron is bound and then excreted.

Chronic: Of long duration; designating a disease showing little change or of slow progression.

Complete Blood Count (CBC): A test that determines the concentration and composition of cellular components of blood. Included in the CBC are values for the number of red blood cells, white blood cells, and platelets in a blood sample.

Congenital: Present at birth.

Cross Match: Type and cross; test in which the blood cells of a donor and a recipient are determined to be compatible or not compatible for a transfusion or transplant.

Cytokines: Growth factors which promote the proliferation and maturation of blood cells; chemicals which are produced naturally by the body and which help to regulate cell growth.

Diamond Blackfan Anemia: A rare anemia generally diagnosed in infancy that results from the failure of the bone marrow to produce sufficient amounts of red blood cells.

Dominant: In genetics, a trait or characteristic that will be expressed in the offspring even though it is carried on only one of the homologous (parental) chromosomes. By contrast, a recessive trait requires that both chromosomes carry the trait for it to be expressed.

Endocrine: System to secrete; the network of ductless glands and other structures that elaborate and secrete hormones directly into the blood stream, affecting the function of specific target organs.

Eosinophil: Another type of granulocyte white blood cell capable of ingesting foreign particles, involved in allergic reactions; normal value 2-3%.

Erythrocyte: AKA red blood cell. A cell that contains hemoglobin and transports oxygen throughout the body.

Erythropoiesis: the process by which red blood cells are made.

Erythropoietin: A hormone/cytokine produced in the kidneys which stimulates red blood cell production.

Etiology: The cause of a disease.

Granulocyte: A general class of white blood cells filled with microscopic granules that release substances into the extracellular environment. These cells help fight bacterial infections and can be involved in allergic reactions.

Hematocrit (Hct): Ratio of red blood cells to plasma in the blood; portion of the blood’s total volume that is made up of red blood cells. Normal values vary: men 45% to 57%; women 37% to 47%; children (depending on age) 36% to 40%.

Hematology: Study of the blood.

Hematopoiesis: The formation of new blood cells.

Hemoglobin (Hgb or Hb): iron-containing protein in red blood cells that binds oxygen and transports oxygen from lungs to other tissues. Hemoglobin with oxygen bound gives arterial blood a red color, hemoglobin lacking oxygen gives venous blood a blue color, until it is exposure to air and oxygen binds. Normal values for men: 14 to 18 g/dl: women 12 to 16 g/dl; children 12 to 16 g/dl.

Hypoplastic: Defective formation in the bone marrow.

Hypertension: A common, often asymptomatic disorder characterized by elevated blood pressure persistently exceeding 140/90 mm Hg in adults; and for children, exceeding what is normal for the child’s age.

Leukocyte: Another name for white blood cells.

Liver Biopsy: A needle is inserted into the liver and a sample taken for analysis (typically iron content in patients with DBA).

Lymphocyte: Any of the white or nearly colorless cells found in blood and lymphoid tissue e.g., lymph nodes, spleen, thymus, tonsils, and sometimes in bone marrow.

Macrocytes: Abnormally large erythrocytes.

Mean corpuscular hemoglobin (MCH): is a calculation of the average amount of hemoglobin inside a red blood cell. Macrocytic RBCs are large so tend to have a higher MCH, while microcytic (smaller) red cells would have a lower value.

Mean corpuscular hemoglobin concentration (MCHC): is a calculation of the average concentration of hemoglobin inside a red cell. Decreased MCHC values (hypochromia, reduced color) are seen in conditions where the hemoglobin is abnormally diluted inside the red cells, such as in iron deficiency anemia and in thalassemia. Increased MCHC values (hyperchromia, increased color) are seen in conditions where the hemoglobin is abnormally concentrated inside the red cells, such as in burn patients and hereditary spherocytosis, a relatively rare congenital disorder.

Mean Corpuscular Volume (MCV): Mean corpuscular volume (MCV) is a measurement of the average size of your RBCs. The MCV is elevated when your RBCs are larger than normal (macrocytic), frequently observed in DBA When the MCV is decreased, your RBCs are smaller than normal (microcytic) as is seen in iron deficiency anemia or thalassemias.

Megakaryocyte: Large cells in the bone marrow from which pieces break off to form platelets.

Multipotent: Having the ability to become more than one cell type.

Neutropenia: Low neutrophil count.

Neutrophil: Type of white blood cell that contains granules that release enzymes that help fight infection; also called polymorphonuclear leukocytes. Normal values depend on age but are generally 50-60 percent of 4,000 to 10,000 in number. For those under age 5, normal values are less than 50%.

Normocellular: Having a normal number of cellular elements in general; not devoid of cells.

Normochromic: Normal color of erythrocytes; normal amount of hemoglobin in each red cell.

Osteoporosis: Loss of bone calcareous matter and increased bone porosity.

Pancytopenia: Low number of all blood cells.

Parvovirus B-19: The cause of a usually benign disease known as Fifth disease; in immunocompromised patients, may cause aplastic anemia.

Platelets: Particles in blood formed from megakaryocytes which form clots therefore preventing bleeding and bruising. Normal values range from 150,000 to 400,000 per microliter of blood. A count below 50,000 can result in spontaneous bleeding; below 5,000 patients are at risk of severe life-threatening bleeds.

Precursor: A substance that precedes another substance.

Progenitor: A parent or ancestor; anything that originates or precedes something else. A red blood cell progenitor could be considered as any cell along the pathway between hematopoietic stem cell and the mature erythrocyte.

Red Blood Cell (RBC): Oxygen-carrying cell in the blood that is produced in the bone marrow which contains hemoglobin; AKA, erythrocyte. Counts refer to the number of cells in a single drop (microliter) of blood. Normal ranges vary according to sex and age.

Refractory: Not responding to treatment.

Reticulocyte: immature red blood cell. A late progenitor along the developmental pathway leading to red blood cells.

Reticulocyte (Retic) Count: Number of immature red blood cells. Immature RBCs/Total RBCs x 100% = retic count.

Reticulocytopenia: Deficiency of reticulocytes in the blood.

SQUID: A non-invasive machine that uses magnetic principles to determine liver iron stores.

Stem Cell: A cell capable of self renewal (making copies of itself) as well as differentiating into other cell types. Hematopoietic stem cells are capable of repopulating all cells of the bone marrow (megakaryocytes, red blood cells, and white cells) after a bone marrow transplant. There are other types of stem cells capable of differentiating into other restricted cell lineages of the human body. Embryonic stem cells are capable of giving rise to all cells of the body.

Thrombocyte: AKA Platelet; clotting factor in the blood.

Thrombocytopenia: Low platelet count.

Thymocytes: T cells; lymphocytes arising in the thymus.

White Blood Cells (WBC): Blood cells that fight infections. Normal values range from 4,000 to 10,000 cells in a microliter of blood (drop) but can be greatly altered by factors such as stress, exercise and disease.

White Blood Cell Differential: Percent of different types of white blood cells in the blood.