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Last Updated: February 03rd, 2012
What is NF2?
Index
- Introduction
- Types of Neurofibromatosis
- Genetics and NF2
- Types of NF2
- NF2 Tumors
- Symptoms and Diagnosis of NF2
- Additional Sources of Information
Introduction
Neurofibromatosis Type II (NF2), or "MISME Syndrome", for "Multiple Inherited Schwannomas, Meningiomas, and Ependymomas", is a genetic neurological disorder that causes benign tumors to grow within the CNS (Central Nervous System) and the PNS (Peripheral Nervous System). NF2 is characterized by bilateral VS's (Vestibular Schwannomas), also known as AN's (Acoustic Neuromas), Schwannoma tumors along the 8th CN the Vesdtibular Nerve are VS's. The majority of NF2 patients (approximately 90%) develop bilateral Vestibular Schwannomas.
Return to TopTypes of Neurofibromatosis
The 3 main forms of NF - NF1, NF2 and Schwannomatosis. The additional forms of NF are a lot less common.
Neurofibromatosis is a genetic condition. NF1 is associated with Chromosome 17. NF2 and Schwannomatosis are both associated with Chromosome 22, and are a lot closer genetically, but are associated with different Genes along that Chromosome. There are 693 Genes on Chromosome 22.
All forms of NF are neurological conditions where tumors develop and grow at some rate. But the 3 forms of Neurofibromatosis are otherwise completely different conditions. Location and tumor types are different for all 3 forms.
Return to TopGenetics and NF2
The NF2 gene is a tumor suppressor gene, which produces the protein known as Merlin, "MERLIN" is an acronym for the "Moesin-Ezrin-Radixin-Like Protein", also referred to as Schwannomin, which is the most common tumor type developed in individuals with NF2. With insufficient amounts of the Merlin protein, tumors develop.
A child can inherit NF2 from a parent who has NF2, or NF2 can be caused by a spontaneous mutation. When NF2 is inherited, it is transmitted from a parent to child at the time of conception. NF2 develops through a Somatic Mosaicism, which means it is inherited through autosomal dominant manner, as a result, there is a 50percent chance that a child will inherit the mutated NF2 gene if either parent has NF2.
It is not uncommon for NF2 to also be a result of a Spontaneous Mutation, also known as de novo mutatio (New Mutation). In Spontaneous Mutation, there is no family history of NF2. Approximately 50% cases doctors see patients for who have NF2, have it as a result of a Spontaneous Mutation.
Frequently in Sporadic Mutations of NF2, Mosaicism occurs. People with a Mosaic mutation of a genetic condition, do not have the mutation in every cell in their body.
It is believed that 1 in every 33,000 people are afflicted with NF2, however since NF2 is uncommon many people are often misdiagnosed. Early diagnosis is suggested since the earlier an individual is known to have NF2 treatment to control tumor development can start to help delay the development of the condition.
Return to TopTypes of NF2
- Wishart - Individuals with Wishart NF2 usually develop symptoms in the late teens to early 20's.
- Gardner - Individuals with Gardner NF2 usually do not develop symptoms until 30 years of age, or older.
NF2 Tumors
- Schwannomas
- Meningiomas
- Ependymomas - Gliomas
- Astrocytoma
- Neurofibromas
Symptoms and Diagnosis of NF2
Tumors for NF2 grow off of nerves in the brain and spine. For more information see: NF2 and the Central Nervous System
In the majority of cases, initial symptoms of NF2 are sensorineural hearing loss, tinnitus and disequilibrium. Theses symptoms are caused by compression of the auditory nerve by a small-sized acoustic neuroma.
Diagnosis of NF2 can be done in different ways:
- Neurologist Examination - This is the most common way NF2 is diagnosed. A Neurologist would likely do both of the following:
- Neurological Examination
- MRI of with and without gadolinium of the brain and spinal cord
- Dermatologist Examination - Having a Dermatologist look for café-au-lait spots on the skin, is a good way to diagnose NF2 early. However, not everyone with NF2 has café-au-lait and if no spots are found it is still possible to have NF2.
- Genetic Testing - Depending on when during pregnancy NF2 started, a genetic test may not be accurate if it says you do not have NF2.
- Otologic Examination - An Otologic (Ear Doctor) or an ENT Doctor (Ear Nose Throat) would have you take either or both:
- Audiometry Hearing Test - Speech Recognition/Discrimination Tests
- ABR - Auditory Brain Stem Response
- MRI - Magnetic Resonance Imaging of with and without gadolinium of the brain and spinal cord
- Neuro-Ophthalmologist - A Neurologist with a specialty in vision, might be able to see signs of tumor pressure in an eye exam, but would usually follow up exam with sending a patient for an MRI before diagnosis.