The neurofibromatoses are genetic disorders of the nervous system. The disorders mainly affect nerve cell tissue and forms mostly benign tumors (noncancerous tumors) on these nerves. There are several types, the most common being neurofibromatosis type 1 (NF1) followed by neurofibromatosis type 2 (NF2).
What is neurofibromatosis type 2 (NF2)?
NF2 involves changes in the NF2 gene, which helps in the production of merlin, or schwannomin, a protein that suppresses tumor formation. The gene is located on chromosome 22.
The main trait of NF2 is that noncancerous (benign) tumors grow on the cranial and spinal nerves. In NF2, the auditory nerves are commonly affected and so the hearing is affected. These types of tumors grow along the auditory nerve that connects the brain and inner ear. The tumors are called vestibular schwannomas or acoustic neuromas. Schwannomas are tumors that are made up of Schwann cells. Very often, the tumors grow on the auditory nerves on both the left and right side of the brain and are called bilateral vestibular schwannomas, which are the main feature of NF2. These tumors often appear before the person reaches age of 30.
Tumors can appear on the skin and on other parts of the nervous system as well, such as the brain and spinal cord.
Who gets neurofibromatosis type 2 (NF2)?
About 1 in 25,000 people throughout the world are born with NF2, according to various estimates. Both males and females are affected in equal numbers. All ethnic groups are affected. It can be inherited, but about half the people with NF2 have no family history. Because it can be inherited, the main risk factor is family history.
Children with NF2 tend to have symptoms related to tumors in the brain and spinal cord. Adults diagnosed with NF2 are usually in the age range of 18 to 24 years old. They tend to have problems due to tumors on the auditory nerves.
What are the symptoms of neurofibromatosis type 2 (NF2)?
Early symptoms of NF2 include:
- Problems with balance (such as dizziness)
- Problems with hearing
- Ringing in the ears, also called tinnitus
For tumors that occur outside of the auditory nerves, symptoms might include:
- Weakness in the face, arms, or legs
- Clouded lenses in one or both eyes (cataracts), often at a young age
- Increase in fluid on the brain