General Question

annholly's avatar

Is nerofibrosis and neurofibromatosis the same thing?

Asked by annholly (10points) May 18th, 2009

Are they two different genetic disorders, or are they just the disease but different versions or what?

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2 Answers

Darwin's avatar

With the way search engines deal with these two terms, someone apparently decided that neurofibrosis and neurofibromatosis are the same thing, the former term used mistakenly for the latter. However they also appear to be separate problems when used accurately, with neurofibrosis a descriptive term for an as-yet not fully understood and rare problem of one or several peripheral nerves.

If you actually read the articles that cite neurofibrosis it seems to be an informal name for a finding of unusual and uncommon lesions on peripheral nerves, similar to those found in a separate disease, progressive hypertrophic polyneuritis or Dejerine-Sottas Syndrome . The article states specifically that it does not include the development of the tumors (the neurofibromas) found in neurofibromatosis and so is not apparently a form of that disease. However, it would seem that researchers don’t know the precise cause of this variant.

There are actually two different types of neurofibromatosis, both genetic disorders but from changes to different genes.

Neurofibromatosis type 1 : NF1, a genetic disorder characterized by a number of remarkable skin findings including multiple cafe au lait (coffee with milk) spots, multiple benign tumors called neurofibromas on the skin, plexiform neurofibromas (thick and misshapen nerves due to the abnormal growth of cells and tissues that cover the nerve), and freckles in the armpit and groin.

The cafe au lait spots increase in number and size with age. Ninety-seven percent of people with NF1 have 6 or more cafe au lait spots by age 20. The skin neurofibromas appear later, usually in the second decade of life. In NF1 there is an increased risk of scoliosis, optic gliomas (benign tumors on the optic nerve), epilepsy, and learning disability. The risk of malignant degeneration of neurofibromas is below 5 percent.

NF1 is inherited in an autosomal dominant manner and is due to mutation of the NF1 gene (in chromosome band 17q11) that encodes a protein called neurofibromin. Half of cases are due to new mutations in the NF1 gene. Prenatal testing is available. Also called von Recklinghausen disease.

Neurofibromatosis type 2 : Abbreviated NF2. A genetic disorder characterized by the growth of benign tumors of both acoustic nerves (the nerves to the ears). These tumors are called acoustic neuromas or, more precisely, vestibular schwannomas. They cause tinnitus (ringing in the ears), hearing loss, and problems with balance. Other findings in NF2 include schwannomas of other nerves, meningiomas, and juvenile cataracts.

NF2 is inherited in an autosomal dominant manner and is due to mutation in the NF2 gene in chromosome band 22q12.2 which encodes a protein called merlin. About 50% of persons with NF2 inherit it from an affected parent and the other 50% with NF2 have a new gene mutation. Anyone with NF2 has a 50% risk of transmitting it to each of their children. Prenatal testing is available. Also known as bilateral acoustic neurofibromatosis and central neurofibromatosis.

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