Neurofibromatoses are genetic disorders of the nervous system. Mainly, these disorders affect the growth and development of nerve cell tissue. The disorders are known as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). NF1 is the more common type of neurofibromatosis. Schwannomatosis has recently been identified as a third and more rare type of neurofibromatosis, but little is known about it.
NF1, also called von Recklinghausen NF or peripheral NF, is characterized by multiple café au lait spots (patches of tan or light brown skin) and neurofibromas (soft, fleshy growths) on or under the skin. Enlargement and deformation of bones and curvature of the spine (scoliosis) may also occur. Occasionally, tumors may develop in the brain, on cranial nerves, or on the spinal cord. More than 50% of people with NF1 also have learning disabilities.
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NF2, also called bilateral acoustic NF (BAN), is much less common than NF1 and is characterized by multiple tumors on the cranial and spinal nerves. Tumors that affect both of the auditory nerves and hearing loss beginning in the teens or early twenties are generally the first symptom of NF2.
What Causes Neurofibromatosis?
Neurofibromatosis is often inherited (passed on by family members through our genes), but 30% to 50% of people newly diagnosed with the disorder have no family history of the condition, which can arise spontaneously through a mutation (change) in the genes. Once this change has taken place, the mutant gene can be passed on to future generations.
What Are the Symptoms of Neurofibromatosis?
The following symptoms appear in people with NF1:
Several (usually 6 or more) café au lait spots
Multiple freckles in the armpit or groin area
Tiny growths in the iris (colored area) of the eye; these are called Lisch nodules and usually do not affect eyesight.
Neurofibromas that occur on or under the skin, sometimes even deep within the body; these are benign (harmless) tumors; however, in rare cases, they can turn malignant or cancerous.
Bone deformities, including a twisted spine (scoliosis) or bowed legs
Tumors along the optic nerve, which may cause eyesight problems
People with NF2 often display the following symptoms:
Loss of hearing
Weakness of the muscles of the face
Cataracts (cloudy areas on the lens of the eye) that develop at an unusually early age
People with schwannomatosis may have the following symptoms:
Pain from the enlarging tumors
Numbness and tingling of the fingers or toes
Weakness in the fingers and toes
How Is Neurofibromatosis Diagnosed?
Neurofibromatosis is diagnosed using a number of tests, including:
Computerized tomography (CT) scans
Magnetic resonance imaging (MRI)
Biopsy of neurofibromas
Tests for particular symptoms, such as hearing or balance tests
Genetic testing (available for families with documented cases of NF1 and NF2); at this time, there is no genetic test available for schwannomatosis.