Neurofibromatosis

Home » Neurofibromatosis » Overview, Types, Incidence and Prevalence, Risk Factors and Causes

Overview

Neurofibromatosis (NF) is a genetic neurological disorder that affects cell growth in nerve tissue. NF produces tumors of the skin, internal organs, and nerves that may become cancerous (malignant). It also can affect bones, causing severe pain and debilitation and may result in learning disabilities, behavioral dysfunction, and hearing and vision loss. There is no cure for neurofibromatosis.

Types
Neurofibromatosis can be inherited as an autosomal dominant trait (a parent with the disorder has a 50% chance of passing it to an offspring) or can result from a spontaneous genetic mutation.

Type 1 neurofibromatosis, also called von Recklinghausen NF, is transmitted on chromosome 17 and is caused by mutation (or rarely, deletion) of the NF1 gene. This type causes multiple areas of hyperpigmentation (i.e., birthmarks) that appear shortly after birth. In late childhood, a few to thousands of tumors appear on the skin (called cutaneous lesions) and under the skin (called subcutaneous lesions). These tumors may become cancerous.

Type 2 neurofibromatosis results from mutation (or rarely, deletion) of the NF2 gene and is transmitted on chromosome 22. In this type, tumors form in the nervous system, usually within the skull (intracranial tumors) and spinal canal (intraspinal tumors). Tumors on the eighth cranial nerve (vestibulocochlear nerve), which are sometimes referred to as acoustic neuromas, are most common. This type causes hearing loss and loss of sense of balance (equilibrium), usually during the late teens or early 20s. These tumors may become cancerous.

Schwannomatosis is a rare form of NF in which multiple benign tumors (schwannomas) form in peripheral nerve fiber cells (called Schwann cells). Schwannomatosis does not cause neurological disabilities or malignant tumors. The hallmark of this condition is chronic pain, which can occur in any part of the body, depending on which peripheral nerves are affected.

Incidence and Prevalence
Neurofibromatosis is the most common genetic neurological disorder that is caused by a single gene. It affects more than 100,000 people in the United States. Type 1 NF affects 1 in 4000 people and is usually diagnosed during childhood. Type 2 affects 1 in 50,000 and is usually diagnosed in early adulthood. Schwannomatosis is rare.

NF occurs throughout the world and affects men and women of all races and ethnic groups.

Risk Factors and Causes

Neurofibromatosis is an inherited disease caused by one of two genetic processes. In 50% of cases, a parent passes the defective NF gene (i.e., NF1 or NF2) to an offspring, resulting in autosomal dominant transmission. The NF1 and NF2 genes have tumor suppressor function. Rarely, neurofibromatosis is caused by deletion of the NF1 or NF2 gene.

In the other 50% of cases, a spontaneous genetic mutation occurs with no known cause, no hereditary link, and no family history of the disease.

Other disorders (e.g., epilepsy, scoliosis) have been linked to NF.

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