Vitelliform macular dystrophy

Vitelliform macular dystrophy

Infobox_Disease
Name = PAGENAME


Caption =
DiseasesDB = 34190
DiseasesDB_mult = DiseasesDB2|31278 | ICD10 =
ICD9 =
ICDO =
OMIM = 608161
OMIM_mult = OMIM2|153700
MedlinePlus =
eMedicineSubj =
eMedicineTopic =
MeshID =

Vitelliform macular dystrophy or vitelliform dystrophy is a genetic eye disorder that can cause progressive vision loss. This disorder affects the retina, specifically cells in a small area near the center of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces.

Diagnosis

Vitelliform macular dystrophy causes a fatty yellow pigment (lipofuscin) to build up in cells underlying the macula. Over time, the abnormal accumulation of this substance can damage cells that are critical for clear central vision. As a result, people with this disorder often lose their central vision and may experience blurry or distorted vision. Vitelliform macular dystrophy does not affect side (peripheral) vision or the ability to see at night.

Researchers have described two forms of vitelliform macular dystrophy with similar features. The early-onset form (known as Best disease) usually appears in childhood; however, the onset of symptoms and the severity of vision loss vary widely. The adult-onset form begins later, usually in middle age, and tends to cause relatively mild vision loss. The two forms of vitelliform macular dystrophy each have characteristic changes in the macula that can be detected during an eye examination.

Pathophysiology

Mutations in the "RDS" and "VMD2" genes cause vitelliform macular dystrophy. Mutations in the "VMD2" gene are responsible for Best disease. Changes in either the "VMD2" or "RDS" gene can cause the adult-onset form of vitelliform macular dystrophy; however, less than a quarter of cases result from mutations in these two genes. In most cases, the cause of the adult-onset form is unknown.

The VMD2 gene provides instructions for making a protein called bestrophin. Although its exact function is uncertain, this protein likely acts as a channel that controls the movement of negatively charged chlorine atoms (chloride ions) into or out of cells in the retina. Mutations in the "VMD2" gene probably lead to the production of an abnormally shaped channel that cannot regulate the flow of chloride. Researchers have not determined how these malfunctioning channels are related to the buildup of lipofuscin in the macula and progressive vision loss.

The "RDS" gene provides instructions for making a protein called peripherin. This protein is essential for the normal function of light-sensing (photoreceptor) cells in the retina. Mutations in the RDS gene disrupt the structures in these cells that contain light-sensing pigments, leading to vision loss. It is unclear why RDS mutations affect only central vision in people with adult-onset vitelliform macular dystrophy.

Inheritance

"Best disease" is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.

The inheritance pattern of adult-onset vitelliform macular dystrophy is uncertain. Some studies have suggested that it may be inherited in an autosomal dominant pattern. Many affected people, however, have no history of the disorder in their family and only a small number of affected families have been reported.

External links

*
* [http://www.emedicine.com/oph/topic700.htm Best's disease - eMedicine.com]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Macular degeneration — Classification and external resources Picture of the fundus showing intermediate age related macular degeneration. ICD 10 …   Wikipedia

  • Macular edema — Classification and external resources ICD 10 H35.8 …   Wikipedia

  • Corneal dystrophy (human) — Main article: corneal dystrophy Corneal dystrophy (human) Classification and external resources ICD 10 H18.5 ICD 9 …   Wikipedia

  • Fuchs' dystrophy — Classification and external resources Fuchs corneal dystrophy. Light microscopic appearance of the cornea showing numerous excrescences (guttae) on the posterior surface of Descemet s membrane and the presence of cysts in the corneal epithelium… …   Wikipedia

  • Meesmann juvenile epithelial corneal dystrophy — Classification and external resources Multiple opaque spots in the corneal epithelium ICD …   Wikipedia

  • dystrophy — Progressive changes that may result from defective nutrition of a tissue or organ. SYN: dystrophia. [dys + G. trophe, nourishment] adiposogenital d. a disorder characterized primarily by obesity and hypogonadotrophic hypogonadism …   Medical dictionary

  • Bestrophin 1 — Bestrophin 1, also known as BEST1, is a human gene.cite web | title = Entrez Gene: BEST1 bestrophin 1| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=7439| accessdate = ] PBB Summary section title = summary …   Wikipedia

  • BEST2 — Bestrophin 2, also known as BEST2, is a human gene.cite web | title = Entrez Gene: BEST2 bestrophin 2| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene Cmd=ShowDetailView TermToSearch=54831| accessdate = ] PBB Summary section title =… …   Wikipedia

  • Eye disease — This is a partial list of human eye diseases and disorders. The World Health Organization publishes a classification of known diseases and injuries called the International Statistical Classification of Diseases and Related Health Problems or ICD …   Wikipedia

  • Diabetic retinopathy — Classification and external resources ICD 10 H36 (E10.3 E11.3 E …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”