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Medical Dictionary


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F (coefficient of inbreeding)
F is the symbol for the coefficient of inbreeding, a way of gauging how close two people are genetically to one another. The coefficient of inbreeding, F, is the probability that a person with two identical genes received both genes from one ancestor.

Take, for example, the mating of first cousins who, by definition, 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.

Fabry disease
A genetic disease due to deficiency of an enzyme called alpha-galactosidase A. This enzyme is essential to the metabolism of molecules known as glycosphingolipids. Without the enzyme, glycosphingolipids accumulate in the kidneys, heart, nerves and throughout the body.

Males with Fabry disease are more severely affected than females since the gene for Fabry disease is on the X chromosome. Males have only one X while females have a second X and therefore some enzyme activity.

Females with partial enzyme activity may not show any symptoms or only late in life. Impaired heart function may be their primary problem.

Diagnosis is made by determining the level of alpha-galactosidase A in blood plasma or by genetic testing to detect the abnormal gene.

Treatment is available only for the signs and symptoms of the disorder. Gene therapy may someday make this a curable disease.

The disease is named for the German dermatologist Johannes Fabry who reported it in 1898, the same year as it was described by the English surgeon William Anderson. The disorder is known alternatively as Fabry-Anderson disease, Anderson-Fabry disease, and angiokeratoma corporis diffusum universale.

Face, masklike
An expressionless face with little or no sense of animation, a face more like a mask than a normal face.

A masklike face is seen in a number of disorders including Parkinson's disease and myotonic dystrophy.

Also called masklike facies.

Facelift operation
A surgical procedure to make the face appear younger. Recovery time is usually one week. Results last approximately ten years. Additional procedures to supplement the facelift—including necklift, blepharoplasty (eyelid surgery), liposuction, autologous fat injection, removal of buccal (cheek) fat pad, forehead lift, browlift, chemical or laser peel, and malar (cheek), submalar or chin implants—may be necessary to achieve the desired results.

Facelift surgery risks
Although infrequent, the risks and complications of facelift surgery include: bleeding, hematoma, bruising; infection; neurological dysfunction (loss of muscle function or sensation), which is usually temporary; widened or thickened scar; loss of hair (around the incision site), asymmetry (unevenness between two sides); and skin necrosis (loss of skin from tissue death).

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.

The Latin word "introitus" comes from "intro", into, within + "ire", to go = to go into. The vagina also has an introitus, an entrance.

Facial nerve
The facial nerve is the seventh cranial nerve. It is a mixed nerve that has fibers both going out and coming in (both efferent and afferent fibers). It supplies the muscles of facial expression.

Paralysis of the facial nerve causes a characteristic picture with drooping of one side of the face, inability to wrinkle the forehead, inability to whistle, inability to close the eye and deviation of the mouth toward the other side of the face. Paralysis of the facial nerve is called Bell's palsy.

Facial nerve paralysis
Loss of voluntary movement of the muscles of one side of the face due to abnormal function of the facial nerve.The facial nerve (also known as the 7th cranial nerve), supplies the facial muscles on one side of the face. The cause of facial nerve paralysis (Bell’s palsy) is not known, but it is thought to be related to a virus (or to various viruses). The disease typically starts suddenly and causes paralysis of the muscles of the side of the face on which the facial nerve is affected. (The facial nerve is also known as the 7th cranial nerve). Treatment is directed toward protecting the eye on the affected side from dryness during sleep. Massage of affected muscles can reduce soreness. Sometimes prednisone is given to reduce inflammation during the first weeks of illness.The prognosis (outlook) of Bell’s palsy is generally good. About 80 percent of patients recover within weeks to months. Conversely, about 20% of patients do less well. The condition was originally described in 1830 by the Scottish anatomist and neurologist Sir Charles Bell (1774- 1842). The word “palsy” is a corruption (and contracture) of the French word “paralysie” which means “paralysis.”

A direct borrowing from the Latin, facies means face.

Faciodigitogenital dysplasia
This disorder is characterized by multiple birth defects involving the face, fingers and genitalia. Features include wide spaced eyes (ocular hypertelorism), front-facing (anteverted) nostrils, a broad upper lip, a malformed ("saddle-bag") scrotum, and laxity of the ligaments resulting in bending back of the knees (genu recurvatum), flat feet, and overly extensible fingers.

This condition is inherited. There are X-linked and autosomal (non-X-linked) forms of the disease.

It is also called the Aarskog-Scott syndrome for DJ Aarskog (1928-) and CI Scott, Jr. (1934-), Norwegian and American pediatricians, respectively, who described it in 1970-71. The gene for the X-linked form of the disease has been mapped to chromosome band Xp11.21.