| Neurofibromatosis type 2 |
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Taugatrefjaæxlager. Samheiti: Neurinomatosis, Recklinghausen's disease, von Recklinghausen's disease (Orðabanki- Ismal) NF2 genið er á litningi nr. 22 og er talið vera eitt af æxlisbælandi genum en það merkir að eðlileg starfsemi þess (líkt og genana p53 og Rb) er að vera hemill á frumuvöxt og skiptingu og þar með sjá til þess að frumur skipti sér ekki óhindrað eins og gerist í æxlum. Stökkbreyting í NF2 erfist með A-litnings ríkjandi erfðamáta sem þýðir að bæði kynin geta fengið sjúkdóminn og að hvert einstakt barn foreldris með sjúkdóminn hefur 50% líkur á því að erfa genið. (upplýsingar fengnar frá NIH) Neurofibromatosis Type 2 (NF-2) is a rare genetic disorder that is primarily characterized by benign (noncancerous) tumors of the nerves that transmit sound impulses from the inner ears to the brain (bilateral acoustic neuromas vestibular schwannomas). Associated symptoms and findings may become evident during childhood, adolescence, or early adulthood. Depending on the exact location and size of the acoustic neuromas/vestibular schwannomas, such findings may include disturbances of balance and walking (gait); dizziness; headache; facial weakness, numbness, or pain; ringing in the ears (tinnitus); and/or progressive hearing loss.
In some individuals with NF-2, additional abnormalities may also be present. These may include loss of transparency of the lenses of the eyes (juvenile posterior subcapsular opacities), progressive visual impairment, or an increased risk of developing certain tumors of the brain and spinal cord (central nervous system). NF-2 results from changes (mutations) of a gene on the long arm (q) of chromosome 22 (22q12.2). The NF-2 gene regulates the production of a protein that functions as a tumor suppressor. In some individuals with NF-2, the disorder is caused by new (sporadic) mutations of the gene that occur for unknown reasons. In other affected individuals, NF-2 is inherited as an autosomal dominant trait. The term "Neurofibromatosis" is sometimes also used to describe a second, distinct form of NF known as Neurofibromatosis Type I (NF-1). More common than NF-2, NF-1 is primarily characterized by the development of multiple noncancerous (benign) tumors of nerves and skin (neurofibromas) and areas of abnormally decreased or increased coloration (hypo- or hyperpigmentation) of the skin, such as pale tan or light brown discolorations (cafe-au-lait spots) on the skin of the trunk or other regions. In contrast, in individuals with NF-2, benign fibrous tumors of the skin (cutaneous neurofibromas) and areas of abnormal pigmentation are considered relatively rare. As with NF-2, NF-1 may be inherited as an autosomal dominant trait or appear to occur randomly due to new (sporadic) genetic changes. |