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Factor VIII
Factor VIII Factor eight, a key factor in the process of blood coagulation (clotting). Lack of normal factor VIII causes hemophilia (hemophilia A). The gene for classic hemophilia was long known to be on the X chromosome. Females carry the gene and transmit it to their hemophiliac sons. Female carriers are normal since they have another X chromosome that contains a normal gene to make factor VIII. Each of their sons has a one-half (50:50) risk of being a hemophiliac. Because the gene for hemophilia was clearly on the X chromosome, it was correctly inferred that the normal gene for Factor VIII was on the X. Factor VIII is also known as antihemophiliac factor or antihemophiliac globulin.
RELATED TERMS--------------------------------------
Blood
The life-maintaining fluid which is made up of plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets; blood circulates through the body's heart, arteries, veins, and capillaries; it carries away waste matter and carbon dioxide, and brings nourishment, electrolytes, hormones, vitamins, antibodies, heat, and oxygen to the tissues.
Coagulation
In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
Hemophilia
A genetic blood disorder, almost always in males, in which blood does not clot properly as a result of an enzyme deficiency.
Gene
1. A unit of DNA that carries information for the biosynthesis of a specific product in the cell. 2. Ultimate unit by which inheritable characteristics are transmitted to succeeding generations in all living organisms. Genes are contained by, and arranged along the length of, the chromosome. The gene is composed of deoxyribonucleic acid (DNA). Each chromosome of each species has a definite number and arrangement of genes, which govern both the structure and metabolic functions of the cells and thus of the entire organism.
Chromosome
A structural unit within a eukaryotic nucleus that carries genes. A chromosome consists of a long, continuous strand of DNA and associated proteins.
Female
The traditional definition of female was "an individual of the sex that bears young" or "that produces ova or eggs". However, things are not so simple today. Female can be defined by physical appearance, by chromosome constitution (see Female chromosome complement), or by gender identification. Female chromosome complement: The large majority of females have a 46, XX chromosome complement (46 chromosomes including two X chromosomes). A minority of females have other chromosome constitutions such as 45,X (45 chromosomes including only one X chromosome) and 47,XXX (47 chromosomes including three X chromosomes).
Risk
In clinical trials, the probability of harm or discomfort for subjects, arising from the test product. Acceptable risk differs depending on the condition for which a product is being tested. A product for sore throat, for example, will be expected to have a low incidence of side effects. However, unpleasant side effects may be an acceptable risk when testing a promising treatment for a life-threatening illness.
SIMILAR TERMS--------------------------------------
Factive
Factive is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): gemifloxacin mesylate.
Factor V
A coagulation factor needed for the normal clotting of blood. Also known as proaccelerin.
Factor V Leiden
A genetic disorder of blood coagulation (clotting) that carries an increased risk of venous thromboembolism - the formation of clots in veins that may break loose and travel through the bloodstream to the lungs or brain. On the molecular level, factor V Leiden is characterized by a G to A substitution at nucleotide 1691 in the gene for factor V that causes a single amino acid replacement in the factor V protein. On the clotting level, factor V Leiden is inactivated about 10 times slower than normal factor V and persists longer in the circulation, resulting in increased generation of thrombin and a hypercoagulable state (thrombophilia).
Factor X
A coagulation factor, a substance in blood essential to the normal clotting process. Production of factor X takes place in the liver and requires vitamin K. The gene for factor X is located on chromosome 13 and is in band 13q34.
Factor, colony-stimulating
A laboratory-made agent similar to a normally existing substance in the body that stimulates the production of blood cells. The colony-stimulating factors (CSFs) include granulocyte colony-stimulating factors (G-CSF) and granulocyte-macrophage colony-stimulating factors (GM-CSF). Treatment with colony-stimulating factors can help the blood-forming tissue recover from the effects of chemotherapy and radiation therapy.
Factor, rheumatoid
Rheumatoid factor is an antibody that is measurable in the blood. It is commonly used as a blood test for the diagnosis of rheumatoid arthritis. Rheumatoid factor is present in about 80% of adults (but a much lower proportion of children) with rheumatoid arthritis. It is also present in patients with other connective tissue diseases (such as systemic lupus erythematosus) and in some with infectious diseases (such as infectious hepatitis).
Factrel
Factrel is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): gonadorelin hydrochloride.
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Facial canal introitus
In anatomy, an introitus is an entrance, one that goes into a canal or hollow organ. The introitus of the facial canal is the entrance to the facial canal, a passage in the temporal bone of the skull through which the facial nerve (the 7th cranial nerve) travels.
Facial muscle
One of the 43 muscles in the human face. The facial muscles convey basic human emotions such as anger, sadness, fear, surprise, disgust, contempt and happiness by very clear facial signals.
Facioscapulohumeral muscular dystrophy
A form of muscular dystrophy that typically begins before age 20 with slowly progressive weakness of the muscles of the face, shoulders, and feet. The severity of the disease is quite variable. Although most people with facioscapulohumeral muscular dystrophy (FSHD) retain the ability to walk, about 20% require a wheelchair. Life expectancy is not shortened. The diagnosis can be confirmed by a DNA test disclosing the deletion of copies of a repeat motif called D4Z4 on chromosome 4. FSHD is inherited in an autosomal dominant manner. Offspring of an affected individual have a 50% chance of inheriting the mutant chromosome 4. About 10-30% of cases are due to a new mutation. Prenatal testing is available.
Factor V
A coagulation factor needed for the normal clotting of blood. Also known as proaccelerin.
Factor V Leiden
A genetic disorder of blood coagulation (clotting) that carries an increased risk of venous thromboembolism - the formation of clots in veins that may break loose and travel through the bloodstream to the lungs or brain. On the molecular level, factor V Leiden is characterized by a G to A substitution at nucleotide 1691 in the gene for factor V that causes a single amino acid replacement in the factor V protein. On the clotting level, factor V Leiden is inactivated about 10 times slower than normal factor V and persists longer in the circulation, resulting in increased generation of thrombin and a hypercoagulable state (thrombophilia).
Factor VIII
Factor X
A coagulation factor, a substance in blood essential to the normal clotting process. Production of factor X takes place in the liver and requires vitamin K. The gene for factor X is located on chromosome 13 and is in band 13q34.
Factor, colony-stimulating
A laboratory-made agent similar to a normally existing substance in the body that stimulates the production of blood cells. The colony-stimulating factors (CSFs) include granulocyte colony-stimulating factors (G-CSF) and granulocyte-macrophage colony-stimulating factors (GM-CSF). Treatment with colony-stimulating factors can help the blood-forming tissue recover from the effects of chemotherapy and radiation therapy.
Factor, rheumatoid
Rheumatoid factor is an antibody that is measurable in the blood. It is commonly used as a blood test for the diagnosis of rheumatoid arthritis. Rheumatoid factor is present in about 80% of adults (but a much lower proportion of children) with rheumatoid arthritis. It is also present in patients with other connective tissue diseases (such as systemic lupus erythematosus) and in some with infectious diseases (such as infectious hepatitis).
Facultative
1. In general, not obligatory but rather capable of adapting to different conditions. The opposite of facultative is obligate. 2. In bacteriology, bacteria that can grow under either aerobic or anaerobic circumstances (with or without oxygen).
Facultative heterochromatin
Chromosome material that can be either heterochromatin or euchromatin. The inactive X chromosome is made up of facultative heterochromatin. When a woman transmits that X chromosome to a son, the chromosome reverts to the euchromatic state and to genetic activity.
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