A
AAV: Stands for adeno-associated virus. This virus is used to deliver a normal Factor gene to human cells in some gene therapy trials.
Adenine: One of the four bases that make up DNA. Abbreviated with an 'A'.
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B
Base: A small molecule inside the larger molecule of DNA. Bases - A, C, G, and T - are arranged in line in a DNA molecule (e.g. CGGTACAGG) and encode instructions for making proteins.
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C
Carrier: A person that carries a gene that causes a disorder, but does not show symptoms.
Chromosome: Chromosomes are packages of DNA found in the nucleus of cells. Humans have 46 chromosomes.
Coagulation: Blood clotting.
Construct: The viral vector used to deliver a gene during gene therapy.
Cytosine: One of the four bases that make up DNA. Abbreviated with a 'C'.
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D
DDAVP: Desmopressin acetate. A drug used to treat some people with mild hemophilia A. The drug helps to release the stored supply of Factor 8.
DNA: Short for deoxyribonucleic acid, DNA is the molecule that carries genetic information.
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F
Factor 8: A blood-clotting protein made in the liver. People with hemophilia A do not produce enough Factor 8 to stabilize blood clots.
Factor 9: A blood-clotting protein made in the liver. People with hemophilia B do not produce enough Factor 9 to stabilize blood clots.
Factor therapy: A hemophilia treatment. People with hemophilia inject themselves with high concentrations of Factor to stop or prevent bleeding.
Fibrinogen: The last molecule in the blood-clotting cascade. Once fibrinogen is snipped by thrombin, the pieces cover and stabilize the clot.
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G
Gel: Hard Jello-like substance that scientists use to measure the size of DNA fragments during DNA diagnostic tests.
Gene: A portion of DNA that contains instructions for making a protein.
Genotype: The genetic composition of a person. Usually used when considering one gene or chromosome (e.g., males have a XY genotype, females have a XX).
Germline transfer: A gene therapy technique that introduces the new gene into the egg or sperm. If successful, the new gene will be passed on to the children of the recipient.
Guanine: One of the four bases that make up DNA. Abbreviated with a 'G'.
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H
Hemophilia A: The type of hemophilia caused by a mutation in the Factor 8 gene.
Hemophilia B: The type of hemophilia caused by a mutation in the Factor 9 gene.
Hemophilic arthropathy: Joint damage caused by repeated episodes of bleeding inside a joint.
HIV: The virus that causes AIDS.
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I
Immune tolerance therapy: Therapy designed to rid the body of inhibitors.
Inhibitors: Antibodies made by the immune system that latch onto injected Factors and mark them for destruction by the body's defenses.
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J
Joint capsule: The tendons and ligaments surrounding the knee joint.
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L
Liver-specific promoter: In hemophilia gene therapy, this is a section of DNA added to the Factor gene that ensures the protein is produced at an elevated level only in the liver.
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M
Mild hemophilia: When Factor activity is between 5 and 35 percent. Only major injuries or surgery cause prolonged bleeding.
Moderate hemophilia: When Factor activity is between one and five percent. Minor injuries produce prolonged bleeding, but spontaneous bleeding is rare.
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N
NIH: Acronym for the National Institutes of Health (in the United States). NIH reviews and funds health research, including gene therapy.
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P
PCR/Polymerase chain reaction: A method to increase or amplify specific sequences of DNA. This method can be used to detect changes in DNA sequence that cause genetic disorders.
Plasma: The fluid left over after all cells are removed from the blood.
Plasma-derived products: Concentrated Factors isolated from donated human plasma.
Platelets: Colorless, disk-shaped cell fragments in the blood that congregate on wounds to stop bleeding.
Prophylaxis: The use of injected Factors to prevent bleeds.
Punnett square: A method of showing the potential offspring of two parents.
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R
Recombinant Factor: Factor proteins for treatment of hemophilia that are made by genetically engineered hamster cells that carry a human Factor gene.
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S
Severe hemophilia: When Factor activity is less than one percent. Minor injuries cause prolonged bleeding, and spontaneous bleeding occurs frequently.
Sex chromosome: Chromosomes (X and Y) that determine an individual's sex.
Sex-linked: Refers to disorders caused by genes on the X chromosome. The inheritance and expression of the disorder is thus linked to gender.
Spontaneous bleeding: Internal bleeding that begins for no apparent reason.
Synovium: A lining surrounding the space inside a joint. The lining absorbs blood after a joint injury, and in the process releases enzymes that damage the joint's cartilage.
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T
T cells: Cells in your bloodstream that recognize foreign cells or molecules and help start an immune defense against the invader. A T-cell clone is a group of identical T cells that recognizes one particular foreign molecule.
Thymine: One of the four bases that make up DNA. Abbreviated with a 'T'.
Thrombin: A protein in the blood-clotting cascade. Once activated, thrombin snips fibrinogen molecules, and the pieces stabilize the clot.
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V
Venous access device: An implant in a vein that allows the introduction of Factor to the bloodstream without the need for injections through the skin.
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X
X-inactivation: A process in female mammals in which one of the two X chromosomes is "turned off."
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