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Founder effect
Founder effect The positive effect on gene frequency when a population (a colony) has only a small number of original settlers (founders) one or more of whom had that gene. For example, the gene for Huntington disease was introduced into the Lake Maracaibo region in Venezuela early in the 19th century. So there are now over a hundred persons with Huntington disease and at least 900 persons at risk for that deadly disease in that region, the largest known aggregation with the Huntington gene in the world.
RELATED TERMS--------------------------------------
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.
Disease
Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs). Disruption sequence: The events that occur when a fetus that is developing normally is subjected to a destructive agent such as the rubella (German measles) virus.
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--------------------------------------
Fountain Valley Regional Hospital
Fountain Valley Regional Hospital is a hospital in Fountain Valley, California (USA).
Fountain Valley Regional Hospital and Medical Center
Fountain Valley Regional Hospital and Medical Center is a hospital in Fountain Valley, Florida (USA).
PREVIOUS AND NEXT TERMS--------------------------------------
Fornices
Plural form of fornix.
Fornix
In anatomy, a vaultlike or arched structure.
Fornix cerebri
An arching fibrous band in the brain connecting the two lobes of the cerebrum. (The cerebrum is the largest part of the brain and consists of two hemispheres separated by a deep longitudinal fissure). Each fornix -- there are two -- in the brain is an arched tract of nerves.
Fornix conjunctivae
The fornix of the conjunctivae refers to loose arching folds connecting the conjunctival membrane lining the inside of the eyelid with the conjunctival membrane covering the eyeball.
Fornix uteri
The fornix of the uterus refers to the anterior (front) and posterior (back) recesses into which the upper vagina is divided. These vaultlike recesses are formed by protrusion of the cervix into the vagina. The fornix uteri is also known as the fornix vaginae (the vaginal fornix).
Founder effect
Fourth cranial nerve
The fourth cranial nerve, the trochlear nerve, is the nerve supply to the superior oblique muscle of the eye, one of the muscles that moves the eye. Paralysis of the trochlear nerve results in rotation of the eyeball upward and outward (and, therefore, double vision).
Fourth disease
A disorder characterized by a rash due to a toxin produced by Staphylococcus aureus (Staph aureus bacteria).
Fourth stage of labor
The hour or two after delivery when the tone of the uterus is established and the uterus contracts down again expelling any remaining contents. These contractions are hastened by breast-feeding, which stimulates production of the hormone oxytocin.
Fourth ventricle
One cavity in a system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord.
Fraction, ejection
The portion of blood that is pumped out of a filled ventricle as a result of a heartbeat. The heart does not eject all of the blood that is in the ventricle. Normally, about two-thirds of the blood is pumped out with each beat. That fraction is referred to the ejection fraction.
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