Coefficient of inbreeding: A measure of how close two people are genetically to each another. The coefficient of inbreeding, symbolized by the letter F, is the probability that a person with two identical genes received both genes from one ancestor.
Take a first-cousin mating. First cousins share a set of grandparents. For any particular gene in the male, the chance that his female first cousin inherited the same gene from the same source is 1/8. Further, for any gene the man passes to his child, the chance is 1/8 that the woman has the same gene and ½ that she transmits that gene to the child so 1/8 X ½ = 1/16. Thus, a first-cousin marriage has a coefficient of inbreeding F =1/16.
The added risks for the offspring of first cousins depend not only upon the coefficient of inbreeding but also upon the genetic family history and test results. For example, first cousins of Italian descent are at increased risk of carrying a gene for beta thalassemia and genetic laboratory tests may confirm that they are both beta-thalassemia gene carriers.
There are always added risks in the mating of closely related persons and those risks are not entirely negligible.
Coenzyme: A substance that enhances the action of an enzyme. (An enzyme is a protein that functions as a catalyst to mediate and speed a chemical reaction). Coenzymes are small molecules. They cannot by themselves catalyze a reaction but they can help enzymes to do so. In technical terms, coenzymes are organic nonprotein molecules that […]
- Coenzyme Q10
Coenzyme Q10: A compound needed for the proper functioning of an enzyme, a protein that speeds up the rate at which chemical reactions take place in the body. Coenzyme Q10 is used to produce energy to fuel cell growth and maintenance. Coenzyme Q10 is thought to improve the function of mitochondria, the “powerhouses” that produce […]
- Coffin-Lowry syndrome
Coffin-Lowry syndrome: An X-linked form of mental retardation in which the affected males have short stature and characteristic face, finger and skeletal abnormalities. Facial features include prominent forehead, widespread eyes, downslanting eyeslits, prominent ears, thick lips and irregular/missing teeth. The hands are large and soft with lax skin and tapering fingers. Skeletal changes include kyphosis/scoliosis […]
Coeval: Of the same or equal age or duration. For example, the two elderly men were coeval with one another. Coeval usually refers to coexistence for a very long time. “Coeval” comes from the Latin “coaevus” meaning “of the same age.” “Coaevus” is derived from the prefix “co-“(“in or to the same degree”) and “aevum” […]
- Cogan corneal dystrophy
Cogan corneal dystrophy: A disorder in which the cornea shows grayish fingerprint lines, geographic map-like lines, and dots (or microcysts). These lines and dots can be seen on examination with a slit-lamp, which focuses a high-intensity light beam through a slit while the examiner uses a magnifying scope to look at the front of the […]