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An introduction to the neurofibromatosis a disorder affecting the chromosomes of the human body

  • Genetics of NF1 Inheritance NF1 is an autosomal dominant disorder, with a nearly even split between spontaneous and inherited mutations;
  • Neurofibromas may be soft, or firm and round;
  • This exposes the tumor for removal and gives access to the brain stem below;
  • Investigators suggest that different mutations of the gene may contribute to the wide variability of symptoms and findings in affected individuals.

Symptoms may become apparent during childhood, adolescence, early adulthood or later in adult life. In some individuals with NF2, additional abnormalities may be present. These may include clouding of the lenses of the eyes juvenile posterior subcapsular opacitiesprogressive visual impairment, or an increased risk of developing certain tumors of the lining of the brain meningiomas and spinal cord central nervous system.

NF2 results from changes mutations in the NF2 gene.

What

The NF2 gene regulates the production of a protein that functions as a tumor suppressor. In more than half of individuals with NF2, the disorder is caused by spontaneous new mutations of the gene.

In other affected individuals, NF2 is inherited in an autosomal dominant pattern. Introduction The term "neurofibromatosis" is also used to describe the second, distinct, and much more common form of NF known as neurofibromatosis 1 NF1. In contrast, in individuals with NF2, benign fibrous tumors of the skin cutaneous neurofibromas and multiple areas of abnormal color pigmentation are considered relatively uncommon.

  1. The visibly-affected areas in segmental patients need not cover the genitalia to confer risk of transmission, a fact which is important for counseling 11.
  2. However, in 1986, geneticists showed that Merrick had not Nf1 but Proteus syndrome, a rare condition that affects fewer than 1 in 1 million people.
  3. Outlook Neurofibromatosis is an incurable genetic disorder of the nervous system.
  4. Causes NF2 is caused by a mutation in the NF2 gene.

As with NF2, NF1 may be inherited in an autosomal dominant pattern or occur randomly due to new gene mutation. These symptoms usually result from the presence of benign tumors on both auditory nerves acoustic neuromas vestibular schwannomas.

Almost all affected individuals develop bilateral vestibular schwannomas by age 30 years. Other tumors of the central nervous system may also develop, and can include neurofibromas, meningiomas, low grade gliomas mainly benign ependymomas of the spinal cordand schwannomas. The size, location, and number of tumors may vary in different people affected. Individuals with NF2 may also develop cloudiness on the lenses of the eyes posterior capsular cataracts at a younger age than would otherwise be expected.

Symptoms of cataracts may include impaired vision, and, in some cases, the progressive loss of vision, although surgery is not usually required.

Causes NF2 is caused by a mutation in the NF2 gene. Several different mutations of the NF2 gene have been identified in individuals with the disorder e.

Investigators suggest that different mutations of the gene may contribute to the wide variability of symptoms and findings in affected individuals.

INTRODUCTION

In some individuals with NF2, the disorder is inherited in an autosomal dominant pattern. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary to cause a particular disease.

The abnormal gene can be inherited from either parent. The risk is the same for males and females. In other individuals with NF2, there is no family history of the disease.

In such cases, NF2 is caused by a new gene mutation. Affected Populations NF2 is a rare disorder that affects males and females in equal numbers.

  • Eventually hearing loss may occur;
  • Genetics of NF1 Inheritance NF1 is an autosomal dominant disorder, with a nearly even split between spontaneous and inherited mutations.

All races and ethnic groups are equally affected by this disorder. The estimated incidence of NF2 is 1 in 33,000 people worldwide. The symptoms of this disease typically become apparent during puberty or early adulthood. The average age of onset is 18 to 24 years. Related Disorders Symptoms of the following disorders can be similar to those of neurofibromatosis 2. Comparisons may be useful for a differential diagnosis: Neurofibromatosis 1 NF1 Neurofibromatosis1 NF1 is a rare inherited disorder of the nervous system and is characterized by the development of tumors on the covering of nerves.

Small, orange-brownish, benign tumors may develop on the iris of the eyes Lisch nodules. Multiple noncancerous benign tumors develop on the covering of the nerves. These tumors can grow on any nerve and may appear at any time, including childhood, adolescence, or adulthood.

Orthopedic problems may develop including curvature of the spine scoliosis and bone loss on weight- bearing long bones pseudoarthrosis.

Neurofibromatosis type 1

Schwannomatosis Schwannomatosis is a disorder characterized by the presence of multiple schwannomas, nearly always without the vestibular schwannomas that are diagnostic of NF2. Patients with schwannomatosis may develop benign tumors in the brain, along the spinal or peripheral nerves. This condition may also be inherited in an autosomal dominant pattern. Schwannomatosis is caused by different genes than for NF2, however, some patients with multiple non vestibular schwannomas eventually fulfill the diagnostic criteria for NF2.

Vestibular schwannomas that are bilateral are associated with NF2. There is usually no genetic predisposition for developing an isolated unilateral vestibular schwannoma. Meningioma A meningioma is a tumor that develops from the membranes that surround the spinal cord and brain meninges.

Multiple meningiomas typically occur in older adults, thus, finding a single meningioma in a younger individual may indicate an underlying genetic condition. The following disorders may be associated with NF2 as secondary characteristics. They are not necessary for a differential diagnosis: Tinnitus Tinnitus describes the experience of hearing sound that does not exist in the environment. They may always be continuous or they may come and go. Eventually hearing loss may occur.

  • Complications The complications for each type of neurofibromatosis are different;
  • This is suspected if two or more children of otherwise unaffected parents develop the disorder 12;
  • People with an ABI wear an external receiver and speech processor;
  • This exposes the tumor for removal and gives access to the brain stem below.

Many ear auditory disorders can be associated with tinnitus including various infections of the ear, obstructions, tumors, drug side effects, and other disorders such as NF2. Cataracts Cataracts are abnormalities in the lens of the eye that cause a loss of transparency opacity. They can occur in one or both eyes and are quite common in elderly people.

Congenital cataracts affect babies or young children and are considered a rare birth defect. The symptoms of cataracts include cloudy vision, and nearsightedness myopia. In many cases, cataracts may result in blindness if left untreated.

Neurofibromatosis type I (von Recklinghausen's disease): A family case report and literature review

Cataracts may have a variety of causes. Some are inherited whereas others are due to injury, aging, or other diseases such as neurofibromatosis. Cataracts in NF2 rarely require surgery. Diagnosis The diagnosis of NF2 is confirmed by a thorough clinical evaluation and specialized testing i.

Molecular genetic testing for mutations in the NF2 gene is available for most affected individuals who have a positive family history.

The Lancet Neurology

Standard Therapies Treatment The treatment of vestibular acoustic neuromas associated with NF2 is the surgical removal of the tumors, when possible. The surgical procedure that is performed is based upon the size and precise location of the tumors. Radiation therapy may be considered for some individuals with this disorder, especially those who are not candidates for surgery. The VEGF inhibitor bevacizumab may also be considered to treat rapidly growing schwannomas but is very expensive.

Other treatment is symptomatic and supportive. Regular monitoring may be required for affected or at-risk individuals. An annual magnetic resonance imaging MRI may be necessary beginning at approximately age 10 to 12 years and continuing until at least the fourth decade of life in addition to regular hearing evaluations. Earlier diagnosis and better treatment lend itself to improved survival in those affected.

Genetic counseling is recommended for people with NF2 and their family members. Investigational Therapies Information on current clinical trials is posted on the Internet at www.

All studies receiving U.