Resources

Glossary

New to Glanzmann Thrombasthenia (GT) or come across a term you don’t recognize?

The Glanzmann's Research Foundation GT Glossary explains common terms, including bleeding, platelets, treatments, genetics, testing, pregnancy, research, and clinical trials.

Use the glossary below to better understand the terminology you may encounter while learning about GT, speaking with your care team, or following the latest research.

A

Activation: The portion of the blood clotting process in which platelets change their shape so they can signal and stick to each other.
Adhesion: The process of platelets sticking to the wall of a torn blood vessel.
Aggregation: The portion of the blood clotting process in which activated platelets stick to each other to form a platelet plug.
Agonist: A chemical substance that binds to a specific receptor on a platelet and triggers a reaction.
AHF: Antihemophilic factor.
Alloantibody: An antibody produced against antigens from another person of the same species, such as antigens on transfused platelets.
Alpha Storage Pool Deficiency: A type of Storage Pool Disease in which the alpha granules inside a platelet are missing. Also called Gray Platelet Syndrome.
Alpha/Delta Storage Pool Deficiency: A type of Storage Pool Disease in which the platelets have few or no alpha and delta (also called dense) granules.
Amicar®: Epsilon aminocaproic acid; a drug that prevents the breakdown of newly formed blood clots in the mouth or nose.
Anemia: When there is not enough of the oxygen-carrying part of the blood or not enough red blood cells.
Angiodysplasia: A condition in which the blood vessels in the stomach or intestines become large and prone to bleed.
Anti-αIIbβ3 antibodies: Antibodies directed against the αIIbβ3 receptor that can develop following exposure to donor platelets.
Antibody: A protein made by the body’s immune system when it encounters a foreign substance. The foreign substance could be a virus or germ or even factor concentrate.
Antifibrinolytic: A medicine that helps prevent blood clots from breaking down too quickly. Tranexamic acid and aminocaproic acid are examples.
Antigen: A name for a foreign substance that causes the body’s immune system to make an antibody.
Antihemophilic factor: Factor VIII.
Artery: A blood vessel that carries oxygen-rich blood away from the heart to the body’s tissues.
Autosomal recessive: Inheritance pattern in which a person generally needs disease-causing variants affecting both copies of a gene to have the disorder.
Autosome: A chromosome that is not a sex chromosome.

B

Bernard-Soulier Syndrome: A very rare disorder in which a person’s platelets do not have enough of the receptor (glycoprotein Tb/TX) needed to bind von Willebrand factor.
Birth Control Pills: (Also known as oral contraceptives) contain the hormones estrogen and progesterone. They may be given to women with bleeding disorders to control heavy menstrual bleeding. The hormones may increase the level of von Willebrand factor and factor VIII in the blood.
Bleeding time test: A test in which a cut is made on the forearm and the length of time for bleeding to stop is measured.
Blood clot: Coagulated blood. The jelly-like mass that results when blood platelets and fibrin mesh to seal a leaking blood vessel.
Bone Marrow Transplant: A type of hematopoietic stem cell transplantation in which blood-forming stem cells are obtained from bone marrow.
Bruise: An injury to the tissue underneath the skin without breaking the skin. Bleeding under the skin can cause it to appear a dark color.

C

Capillaries: Very small blood vessels which connect the smallest arteries with the smallest veins. The capillaries allow oxygen and nutrients to pass from the blood to the body’s cells. They also carry waste away from the cells.
Carrier: In genetics, a person who has a certain gene but doesn’t have the condition caused by that gene. The gene can be passed on to offspring.
CDC: The Centers for Disease Control and Prevention. A government agency which tracks and studies diseases and helps plan ways to prevent them.
Chromosome: A tiny rod-shaped structure in the nucleus of each body cell. The body’s genes are on the chromosomes.
Chronic: Long lasting. Going on without stopping.
Clinical trial: A research study involving people that evaluates medical interventions or other health-related outcomes.
Clot: See Blood Clot.
Clotting: The sealing of a blood vessel with coagulated blood.
Coagulation: Clotting. The process in which liquid blood is changed into a jelly-like solid to seal an injured blood vessel.
COBRA: Consolidated Omnibus Budget Reconciliation Act. A national law that allows some employees who have lost group health insurance coverage to buy insurance for themselves or their families for a limited period of time.
Collagen: The major protein that forms bone, cartilage, tendons, and other connective tissue.
Compound Heterozygous: Having two different disease-causing variants, one in each copy of the same gene.
Comprehensive care: A way of giving health care in which a team of professionals works with the patient to improve his or her physical, emotional, and mental well-being. The care is usually given in one place, a hemophilia treatment center (HTC), so the experts can work together.
Congenital: The condition of being present from birth. A congenital disorder is one that a person has had all of his or her life.
Consanguinity: A biological relationship between two people who share a relatively recent common ancestor. Because Glanzmann Thrombasthenia is inherited in an autosomal recessive manner, consanguinity can increase the chance that both parents carry the same disease-causing variant.
Cryoprecipitate: A layer of blood plasma that is rich in clotting proteins. Cryoprecipitate is made through a process of freezing and thawing plasma.
Cyklokapron: The brand name for tranexamic acid. It is a medicine that helps keep blood clots from being broken down too quickly by the body.

D

DDAVP®: Desmopressin acetate. A medicine used to treat some factor deficiencies and von Willebrand disease.
Delta Storage Pool Deficiency: A type of Storage Pool Disease in which the platelets have few or no dense (or delta) granules.
Dense granules: Storage spaces inside platelets that hold chemicals that are necessary for platelets to function normally.
Desmopressin acetate: See DDAVP®.
DNA: Deoxyribonucleic acid. The substance in chromosomes that carries the genetic information.
Dominant: In genetics, dominant and recessive refer to the relationship of a pair of genes. In a person, there are two genes, one on each of a matching pair of chromosomes, for traits such as curly hair, eye color, or hemophilia. The genes, which come from the mother and the father, may be the same or different. If they are different, the trait which shows up and the gene directing it are said to be dominant. The gene for the trait or characteristic that does not show up is recessive. A gene for a recessive trait never shows its effect unless it joins with another recessive gene or a dominant gene is not present.
Donor: A person from whom blood is drawn to be used by others.

E

Ecchymosis: A black-and-blue discolored area of the skin caused by bleeding into the subcutaneous tissue. A bruise.
Electron microscopy: The use of an electron microscope to see objects up to two million times larger than their actual size.
Endometrial ablation: A medical procedure that removes or destroys the lining of the uterus, resulting in decreased bleeding from periods.
Endothelial cells: The cells that line the inside walls of blood vessels. Together they are called the endothelium.
Enzyme: A type of protein that speeds up specific chemical reactions. Epistaxis - the medical name for a nosebleed.
Epistaxis: Medical term for a nosebleed. It is actually buried inside your current Enzyme definition rather than having its own entry.
Estrogen: The primary sex hormone in women. Men have this hormone in their bodies also, though in much lower amounts.

F

Factor: A protein in the blood that is needed to make the blood clot.
Factor Concentrate: Factor VIII or IX that has been made into a powder.
Factor I: (Factor one) Another name for fibrinogen, a protein in the blood that is converted to fibrin as part of the clotting process.
Factor IX: (Factor nine) The clotting factor protein that is decreased in people with hemophilia B.
Factor replacement therapy: The method in which a person with hemophilia is given, through a needle in a vein, the blood clotting factor he lacks.
Factor VIII: (Factor eight) The clotting factor protein that is decreased in people with hemophilia A.
Fibrin: Strands of protein which weave around and through a platelet plug to form a blood clot.
Fibrinogen: A protein in the blood that is converted to fibrin as part of the clotting process. Also known as Factor I.
Fibrinolysis: The breakdown of fibrin in a blood clot to let the blood flow again.
Fibrous: Made up of slender, thread-like strands.
Fifth disease: A common childhood illness caused by a virus (human parvovirus B 19). It is spread like a cold and is usually very mild. It usually starts as a red rash on the cheeks, giving the disease its other name, “slap face disease.” The rash spreads to other parts of the body and lasts from one to three weeks. There is no vaccine or treatment for Fifth Disease. It is believed that having the disease makes you immune to ever having it again. Fifth Disease got its name because at one time it was the fifth disease on a list of the common causes of rash and fever in children.
Flow cytometry: Laboratory technique that can measure proteins on platelets, including αIIbβ3, and can assist in diagnosing GT.

G

Gastrointestinal: Referring to the stomach and the intestines.
Gastrointestinal Bleeding: Bleeding that occurs anywhere in the digestive tract, including the stomach or intestines.
Gene: The basic unit of heredity. Genes are the blueprints for the body. Each gene has a certain position on a chromosome.
Gene modifiers: Genes that change the severity or progression of a disorder in someone with a disorder caused by a single gene. For example, someone may have the gene for a bleeding disorder but has fewer symptoms than expected because he or she has other genes that are modifying the effect of the bleeding disorder gene.
Gene mutation: A change that alters the instructions carried by a gene, producing a baby that is unlike either parent in a certain way. This change in the gene is permanent.
Gene therapy: An investigational approach intended to treat disease by adding, replacing, or modifying genetic material in a person's cells.
Genetic defect: A mutation in a gene that causes it to no longer work correctly.
Genetic testing: Testing DNA for variants in genes such as ITGA2B and ITGB3.
Genetics: The type of science that studies heredity.
Genotype: A person's genetic makeup, including the specific genetic variants they carry.
Giant Platelet Syndrome: A less common name for Bernard-Soulier Syndrome.
Gingival bleeding: Bleeding from the gums.
Glanzmann thrombasthenia (GT): A rare inherited bleeding disorder in which platelets cannot properly stick to each other to form a platelet plug. GT is caused by changes in the ITGA2B or ITGB3 genes, which affect the platelet receptor αIIbβ3 (glycoprotein IIb/IIIa). People with GT typically have a normal platelet count, but the platelets do not function normally, which can result in prolonged or excessive bleeding.
Glycoprotein Ib/IX: A receptor on the surface of a platelet where von Willebrand factor normally attaches. The platelets of people with Bernard Soulier Syndrome do not have enough glycoprotein Ib/IX. Without enough glycoprotein lb/TX, von Willebrand factor is not able to glue the platelet to the wall of an injured blood vessel.
Glycoprotein IIb/IIIa: A receptor on the surface of a platelet where fibrinogen can attach. The fibrinogen binds platelets together (aggregation). People with Glanzmann’s thrombasthenia have decrease amounts of, or abnormal. glycoprotein IIb/IIIa.
Granules: Storage spaces inside platelets that normally hold different chemicals and proteins.
Gray Platelet Syndrome: See Alpha Storage Pool Deficiency.

H

Hemarthrosis: Blood in a joint.
Hematologist: A doctor who specializes in disorders of the blood.
Hematoma: A swelling under the skin caused by a mass of clotted or partly clotted blood that has leaked out of a blood vessel.
Hematopoietic Stem Cell: A type of stem cell that can develop into the different types of blood cells, including red blood cells, white blood cells, and platelets.
Hematopoietic Stem Cell Transplantation (HSCT): A procedure that replaces a person's blood-forming stem cells with healthy stem cells from a donor. Also commonly called a bone marrow or stem cell transplant.
Hematuria: Blood in the urine.
Hemophilia: A life-long, hereditary blood disorder in which bleeding lasts longer than normal. it is caused by a defect in a protein needed for blood clotting.
Hemophilia Treatment Center: A system of clinics established by the federal government to provide specialized, comprehensive care to people with inherited bleeding disorders.
Hemorrhage: Bleeding.
Hemorrhoids: Inflammation and swelling of veins in the rectum and anus. Hemorrhoids can be inside or outside the anus and are prone to bleeding.
Hemostasis: The stopping of blood flow.
Hemostatic Agent: A medicine, product, or material used to help stop or control bleeding.
Hereditary: Passed in the genes from parent to offspring. The basic unit of heredity is the gene.
HIV: Human Immunodeficiency Virus, the virus that causes AIDS.
Hives: Red, itchy bumps on the skin caused by an allergic reaction.
HLA-matching: A way of determining the compatibility of donated blood. Blood that has been HLA-matched will most likely not cause a reaction in the immune system of the person receiving the blood.
Homozygous: Having the same genetic variant in both copies of a particular gene.
HTC: Hemophilia Treatment Center.
Hysterectomy: Surgery to remove a woman’s uterus.

I

Immune system: The body’s defense network which fights harmful germs or substances.
Infusion: Putting fluid other than blood into a vein.
Inhibitor: An antibody in the blood that reacts to infused factor and hinders clotting.
Injection: The use of a syringe and needle to put a fluid (most often a medicine) into tissue or a vein. A shot.
Integrin alpha IIb beta 3 (αIIbβ3): Modern name for the platelet receptor traditionally called glycoprotein IIb/IIIa.
Intramuscular injection: An injection given deep into a muscle.
Intravenous treatment: Putting fluid into a vein by means of a needle passing through the skin. The needle is attached to tubing or a syringe containing the fluid.
Invasive procedures: Medical practices that open the skin or go beneath the skin.
Iron deficiency: Insufficient iron in the body, which can occur as a result of repeated or prolonged bleeding.
Iron-Deficiency Anemia: Anemia caused by insufficient iron in the body. Repeated or prolonged bleeding can lead to iron deficiency and iron-deficiency anemia.
ITGA2B: Gene that provides instructions for making the alpha IIb component of the platelet αIIbβ3 receptor. Variants can cause Glanzmann Thrombasthenia.
ITGB3: Gene that provides instructions for making the beta 3 component of the platelet αIIbβ3 receptor. Variants can cause Glanzmann Thrombasthenia.
IV line: See Intravenous treatment.

J

Joint: The place where two or more bones come together.

K

Known donor pool: A way of trying to reduce the risk of infection from a blood transfusion by only using blood from people who have been identified and screened by the person receiving the blood.

L

Leukocyte: Another name for a white blood cell. Leukocytes are part of the immune system to defend the body against infection.

M

Marrow: The tissue inside of bones that produces the cells of the blood.
Medicaid: A government program which pays medical bills for certain low-income people.
Medicare: A government health insurance program for people age 65 and older and certain disabled people.
Menarche: A person's first menstrual period.
Menopause: The time in a woman’s life, usually between age 45 and 55, when her ovaries stop releasing eggs and she ceases having a monthly period.
Menorrhagia: Heavy and prolonged menstrual bleeding. Periods that consistently last longer than seven days with heavy bleeding.
Menstrual period: Also called menstruation or just a “period.” The shedding of the lining of the uterus through the vagina. On the average, it occurs every 28 days and lasts from three to five days.
Menstruation: A woman’s monthly flow of blood and tissue from her uterus, often called her “period.” Menstruation begins at puberty and ends at menopause.
Miscarriage: The sudden ending of a pregnancy before the fetus is able to survive outside the womb. A miscarriage is most likely to happen early in the pregnancy (during the first trimester).
Mucosal bleeding: Bleeding from mucous membranes, such as the nose, mouth, gastrointestinal tract, or reproductive tract.
Multimer: One of the parts of the von Willebrand factor protein.

N

NovoSeven®: The brand name for recombinant factor VIIa.

O

Obstetrician: A doctor who specializes in pregnancy and childbirth.
Orthopedist: A doctor who treats disease, injuries, and deformities of body parts such as joints, muscles, or bones that are used in movement.

P

Pathogenic variant: A genetic variant with sufficient evidence that it causes or contributes to disease.
Periods: See Menstrual period.
Petechiae: Tiny red dots under the skin caused by bleeding from capillaries.
PFA-100®: A Platelet Function Analyzer, a machine that measures the closure time of a sample of blood. This is a measure of the adhesion and aggregation abilities of the platelets in the blood.
Phenotype: The observable characteristics of a condition, such as the symptoms and severity of bleeding a person experiences.
Physical therapy: Methods used to maintain the health of, and to treat diseases of, muscles, joints, and nerves. Some of the methods used are regular exercise, water, and ice.
Plasma: The liquid part of the blood. Plasma contains the clotting factors.
Plasmapheresis: A way of donating blood in which a unit of blood is taken from the person’s arm, the liquid (plasma) portion is separated from the blood cells, and the cells are put back in the donor’s body. Since only plasma is taken from the donor, the recovery time is shorter than with donating whole blood.
Plasmin: An enzyme in the blood that can break down the fibrin in a clot.
Platelet: A small disk-shaped particle in the blood that is used in the clotting process. Also called a thrombocyte.
Platelet aggregation testing: A test to determine how well platelets clump together after a chemical (called an agonist) is added to a blood sample.
Platelet count: A blood test to see how many platelets are present in the blood. In an adult, the normal count is about 150,000 to 400,000 platelets in each cubic millimeter (mm of blood.
Platelet plug: A weak fix of a leaking blood vessel. It is made when platelets begin sticking to each other at the site. Platelet plug formation is part of the blood clotting process.
Platelet refractoriness: When platelet transfusions do not produce the expected response, often because of immune or other factors.
Platelet transfusion: Transfusion of donor platelets to help control or prevent bleeding.
Policy: The printed document that states the terms (rules and information) of an insurance contract.
Porcine factor: Factor VIII concentrate made from the blood of pigs. It is mainly used to treat bleeds in people with an inhibitor to factor VIII. Porcine factor must be kept frozen until it is used.
Port: A medical device that has two main parts: the small, round metal port that has a rubber-like top and the soft plastic tube that is connected to it. During surgery, the port is put under the skin and the tube is put into a large vein in the upper chest. After it heals, medicine may be given by sticking a special needle through the skin into the port.
Postpartum Hemorrhage: Excessive bleeding following childbirth.
Pre-existing condition: A health problem that has been discovered before the date that a person’s insurance coverage begins.
Premium: The payment that a policyholder is required to make to keep an insurance policy in force.
Prophylactic: Something that protects against or prevents disease. In hemophilia, a prophylactic treatment is factor given to prevent a bleed from happening.
Prophylaxis: Treatment given to prevent bleeding rather than treating a bleed after it occurs. Your glossary has "prophylactic," but prophylaxis itself would be useful.

R

Receptor: One of many spots on the surface of a platelet that is designed to attach to a certain protein or chemical such as von Willebrand factor or fibrinogen.
Recessive: See Dominant.
Recombinant factor concentrate: A very pure type of factor concentrate that is not made from human blood. It is produced by certain animal cells that have been genetically altered to make human factor.
Recombinant factor VIIa (rFVIIa): A laboratory-produced clotting protein used in certain circumstances to help control bleeding. NovoSeven is a brand of rFVIIa. Your glossary currently lists NovoSeven but does not separately define rFVIIa.
Red blood cells: Also called erythrocytes. The most common cells in the blood. They carry oxygen from the lungs to all parts of the body.
Rider: An amendment to an insurance policy that changes the policy by adding to or taking away from its benefits or excluding certain conditions from coverage.
Ristocetin: An antibiotic that is no longer used to treat infections. It is now used to diagnose certain bleeding disorders. In normal blood, ristocetin acts as an agonist, causing platelets to clump together (agglutination). If platelets do not clump normally when exposed to ristocetin, it can indicate a problem with the von Willebrand factor.

S

Secretion: The process of forming a platelet plug in which platelets release chemicals into the bloodstream. These chemicals signal other platelets to come and help cover the tear in the blood vessel.
Self-infusion: The act of giving factor concentrate to yourself with little or no outside help.
Spleen: A fist-sized organ found in the left side of the abdomen above the stomach. The spleen destroys old and damaged cells, including platelets. It also contains white blood cells to help fight infections.
Spontaneous bleeding: Bleeding that begins without an injury or any other known cause.
Stimate®: A brand name for the nasal spray form of desmopressin acetate.
Storage Pool Disease: Several rare bleeding disorders in which the granules inside of the platelets are not normal.
Subcutaneous injections: Injections (shots) given into the tissue just under the skin.
Symptomatic carrier: A woman who carries the gene for hemophilia and experiences bleeding problems herself.

T

Thrombocyte: Another name for a platelet.
Thrombocytopenia: A below normal number of platelets in the blood.
Thyroid gland: A butterfly-shaped gland in the neck that produces hormones. It helps control metabolism - how quickly or slowly the body uses energy.
Tourniquet: A band of material, such as rubber, which goes around a limb to stop or slow the flow of blood for a short time.
Tranexamic acid: See Cykiokapron®.
Transfusion: Adding whole blood, a blood product, or other substance to the blood stream by means of a needle in a vein.

U

Unit: One unit of factor VIII or IX is the amount of factor VIII or IX activity found in 1 milliliter of normal plasma.
Uterus: Commonly called the “womb.” The pear-shaped organ in a woman’s abdomen where a fertilized egg can grow into a fully-developed baby.

V

Variant: A difference in a DNA sequence. Some genetic variants can cause disease while others do not.
Vasoconstriction: Narrowing of the blood vessels.
Vein: Blood vessel which carries blood from any part of the body back to the heart.
Venipuncture: Sticking a needle into a vein.
Virus: A tiny particle that causes disease. Viruses take over living cells and use them to reproduce.
von Willebrand Disease: A blood clotting disorder in which the platelets have a decreased ability to plug tears in the walls of blood vessels. It is transmitted genetically and can affect both men and women.
von Willebrand factor: A blood protein important in the clotting process. It carries the factor VIII protein in the blood until it is needed. It also binds platelets to an injured blood vessel to stop bleeding.
VWD: von Willebrand Disease.
VWF: von Willebrand factor.

W

White blood cells: The common name for leukocytes. White blood cells are part of the immune system to defend the body against infection.