Dystrophy, cone

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Dystrophy, cone

Dystrophy, cone

A disease of the cones, the specialized light-sensitive cells that act as photoreceptors in the retina of the eye, providing sharp central vision and color vision. The cone dystrophies are a form of genetic macular degeneration characterized by progressive deterioration of the cones that leads to the distinctive triad of loss of color vision, photophobia, and reduced central vision. Cone dystrophy genes have been mapped to chromosome regions 6p21.1, 6q25-q26, 17p12-13, and Xp21.1-p11.3. In region 6p21.1, mutations have been found in the gene that encodes GCAP1, a key component in the recovery of photoreceptor cells to the dark-adapted state after exposure to a light stimulus.

RELATED TERMS
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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.

Retina
A membrane lining the inside of the back of the eye that contains light-sensitive nerve cells that convert focused light into nerve impulses, making vision possible.

Eye
The organ of sight. The eye has a number of components. These components include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.

Central
In anatomy and medicine (as elsewhere), central is the opposite of "peripheral" which means away from the center.

Vision
The sense of sight.

Cone
One of the two light receiving retinal cells (the other is the rod) that is responsible for daylight vision (e.g., color vision, high visual acuity, bright light vision). The area of the retina that provides central or reading vision, known as the fovea, contains only cones.

Genetic
Hereditary. Having to do with the genes.

Triad
Triad 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): acetaminophen; butalbital; caffeine.

Photophobia
Severe discomfort to bright lights. Usually a symptom of eye disease, such as glaucoma, in an infant or retinal disease in a child or adult. Sometimes treated with dark sunglasses.

Dystrophy
Partial atrophy of tissue or an organ as a result of imperfect cell nutrition.

Genes
Basic, functional units of heredity, each occupying a specific place on a chromosome.

Chromosome
A structural unit within a eukaryotic nucleus that carries genes. A chromosome consists of a long, continuous strand of DNA and associated proteins.

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.

Photoreceptor
A light sensitive neuron. Photoreceptors interact with light which produces changes in their electrical properties which are communicated to other neurons. They constitute the first stage in the physiological process which underlies vision. The human retina, like the retina of most vertebrates, contains two broad classes of photo-receptors, rods and cones.

SIMILAR TERMS
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Dysthymia
A type of depression involving long-term, chronic symptoms that are not disabling, but keep a person from functioning at "full steam" or from feeling good. Dysthymia is a less severe type of depression than what is accorded the diagnosis of major depression. However, people with dysthymia may also sometimes experience major depressive episodes, suggesting that there is a continuum between dysthymia and major depression.

Dystocia
When labor does not progress. Uterine dystocia is when contractions donot intensify; shoulder dystocia is when a baby's

Dystocia, fetal
Dystocia caused by the fetus due to its size (too big), shape or position in the uterus.

Dystonia
Dystonia is a neurological movement disorder with involuntary muscle contractions, forcing specific parts of the body into abnormal movements or positions, sometimes causing pain.

Dystonia musculorum deformans (DMD)
Also called torsion dystonia, this is a fortunately rare, generalized dystonia (a state of abnormal -- either excessive of inadequate -- muscle tone) that can be inherited, usually begins in childhood, and becomes progressively worse. It can leave individuals seriously disabled and confined to a wheelchair.

Dystonia, dopa-responsive (DRD)
A condition that typically begins in childhood or adolescence with progressive difficulty in walking and, in some cases, spasticity and can be successfully treated with drugs. Segawa dystonia is an important variant of DRD. In Segawa dystonia, the symptoms fluctuate during the day from relative mobility in the morning to increasing disability in the afternoon and evening and after exercise. DRD may not only be rare but also rarely diagnosed since it mimics some forms of cerebral palsy.

Dystonia, idiopathic torsion
A form of dystonia known as early-onset torsion dystonia (also called generalized torsion dystonia) begins in childhood around the age of 12. Symptoms typically start in one part of the body, usually in an arm or leg, and eventually spread to the rest of the body within about 5 years. Early-onset torsion dystonia is not fatal, but it can be severely debilitating.

Dystonia, oromandibular
Oromandibular dystonia affects the muscles of the jaw, lips, and tongue. The jaw may be pulled either open or shut, and speech and swallowing can be difficult.

Dystonia, Segawa
An important variant form of dopa-responsive dystonia (DRD). DRD typically begins in childhood or adolescence with progressive difficulty in walking and, in some cases, with spasticity. DRD, by definition, can be successfully treated with dopa. In Segawa dystonia, the symptoms fluctuate during the day from relative mobility in the morning to increasingly worse disability in the afternoon and evening and after exercise.

Dystonia, torsion
A form of dystonia known as early-onset torsion dystonia (also called idiopathic or generalized torsion dystonia) begins in childhood around the age of 12. Symptoms typically start in one part of the body, usually in an arm or leg, and eventually spread to the rest of the body within about 5 years. Early-onset torsion dystonia is not fatal, but it can be severely debilitating. Most children with the disorder are unable to perform the simplest of motor tasks and are confined to a wheelchair by the time they reach adulthood.

Dystopia
Displacement.

Dystrophic epidermolysis bullosa
A blistering skin condition inherited in both autosomal dominant and recessive manners and in which the filaments that anchor the epidermis to the underlying dermis are either absent or do not function. This is due to defects in the gene for type VII collagen, a fibrous protein that is the main component of the anchoring filaments.

Dystrophin
A protein, a chemical substance made by muscle fibers.

Dystrophy
Partial atrophy of tissue or an organ as a result of imperfect cell nutrition.

Dystrophy, autoimmune polyendocrinopathy
Dystrophy, autoimmune polyendocrinopathy-candidiasis-ectodermal (APECED) is a genetic autoimmune disease with an extraordinary array of clinical features but characterized most often by at least 2 of the following 3 findings: hypoparathyroidism -- underfunction of the parathyroid glands which control calcium, candidiasis (yeast infection), and adrenal insufficiency (underfunction of the adrenal gland). APECED was the first systemic (bodywide) autoimmune disease found due to a defect in a single gene.

Dystrophy, muscular
One of a group of genetic diseases characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement. The muscles of the heart and some other involuntary muscles are also affected in some forms of muscular dystrophy, and a few forms involve other organs as well. The major forms of muscular dystrophy include: Duchenne muscular dystrophy; Becker muscular dystrophy; limb-girdle muscular dystrophy; facioscapulohumeral muscular dystrophy; congenital muscular dystrophy; oculopharyngeal muscular dystrophy; distal muscular dystrophy; Emery-Dreifuss muscular dystrophy and myotonic dystrophy. Muscular dystrophy can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later. Duchenne muscular dystrophy is the most common kind of muscular dystrophy affecting children. Myotonic dystrophy is the most common of these diseases in adults.

Dystrophy, myotonic
An inherited disease in which the muscles contract but have decreasing power to relax -- this phenomenon is termed myotonia (irritability and prolonged contraction of muscles). The disease also produces leads to a mask-like expressionless face, premature balding, cataracts, and heart arrhythmias (abnormalities in heart rhythm). The onset of such problems is usually in young adulthood. However, onset can be at any age and the disease is extremely variable in the degree of severity.

PREVIOUS AND NEXT TERMS
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Dystonia, oromandibular
Oromandibular dystonia affects the muscles of the jaw, lips, and tongue. The jaw may be pulled either open or shut, and speech and swallowing can be difficult.

Dystonia, Segawa
An important variant form of dopa-responsive dystonia (DRD). DRD typically begins in childhood or adolescence with progressive difficulty in walking and, in some cases, with spasticity. DRD, by definition, can be successfully treated with dopa. In Segawa dystonia, the symptoms fluctuate during the day from relative mobility in the morning to increasingly worse disability in the afternoon and evening and after exercise.

Dystonia, torsion
A form of dystonia known as early-onset torsion dystonia (also called idiopathic or generalized torsion dystonia) begins in childhood around the age of 12. Symptoms typically start in one part of the body, usually in an arm or leg, and eventually spread to the rest of the body within about 5 years. Early-onset torsion dystonia is not fatal, but it can be severely debilitating. Most children with the disorder are unable to perform the simplest of motor tasks and are confined to a wheelchair by the time they reach adulthood.

Dystrophic epidermolysis bullosa
A blistering skin condition inherited in both autosomal dominant and recessive manners and in which the filaments that anchor the epidermis to the underlying dermis are either absent or do not function. This is due to defects in the gene for type VII collagen, a fibrous protein that is the main component of the anchoring filaments.

Dystrophy, autoimmune polyendocrinopathy
Dystrophy, autoimmune polyendocrinopathy-candidiasis-ectodermal (APECED) is a genetic autoimmune disease with an extraordinary array of clinical features but characterized most often by at least 2 of the following 3 findings: hypoparathyroidism -- underfunction of the parathyroid glands which control calcium, candidiasis (yeast infection), and adrenal insufficiency (underfunction of the adrenal gland). APECED was the first systemic (bodywide) autoimmune disease found due to a defect in a single gene.

Dystrophy, cone

Dystrophy, muscular
One of a group of genetic diseases characterized by progressive weakness and degeneration of the skeletal or voluntary muscles which control movement. The muscles of the heart and some other involuntary muscles are also affected in some forms of muscular dystrophy, and a few forms involve other organs as well. The major forms of muscular dystrophy include: Duchenne muscular dystrophy; Becker muscular dystrophy; limb-girdle muscular dystrophy; facioscapulohumeral muscular dystrophy; congenital muscular dystrophy; oculopharyngeal muscular dystrophy; distal muscular dystrophy; Emery-Dreifuss muscular dystrophy and myotonic dystrophy. Muscular dystrophy can affect people of all ages. Although some forms first become apparent in infancy or childhood, others may not appear until middle age or later. Duchenne muscular dystrophy is the most common kind of muscular dystrophy affecting children. Myotonic dystrophy is the most common of these diseases in adults.

Dystrophy, myotonic
An inherited disease in which the muscles contract but have decreasing power to relax -- this phenomenon is termed myotonia (irritability and prolonged contraction of muscles). The disease also produces leads to a mask-like expressionless face, premature balding, cataracts, and heart arrhythmias (abnormalities in heart rhythm). The onset of such problems is usually in young adulthood. However, onset can be at any age and the disease is extremely variable in the degree of severity.

Dysuria
Painful or difficult urination. This includes burning on urination. Dysuria is most commonly due to bacterial infection of the urinary tract causing inflammation of the bladder (cystitis) or kidney (pyelonephritis). In women, dysuria may also reflect inflammation of the vagina (vaginitis) or vulva (vulvitis). And in men, dysuria may be due to inflammation of the prostate (prostatitis) or the urethra (urethritis) from gonorrhea or chlamydia.

Danish doctor
A doctor who, being or not a citizen of that country, has been admitted to practice medicine in Denmark.

Downunder doctor
A doctor who, being or not a citizen of that country, has been admitted to practice medicine in Australia or New Zealand.

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This dictionary contains 25007 terms.

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