Neurofibromatosis Type 2

Neurofibromatosis is a group of genetic disorders, which cause an increased risk of abnormal growths of the nerve sheath (nerve sheath tumors). The nerve sheath is the tissue that wraps around the nerve cells (neurons) to provide insulation and protection.

There are several types of Neurofibromatosis:

1. Neurofibromatosis Type 1.
2. Neurofibromatosis Type 2 (also known as NF2-related schwannomatosis).
3. Schwannomatosis (also known as non-NF2-related schwannomatosis).
4. Legius syndrome: a subset of Neurofibromatosis Type 1 in which there is no tumor development.

Vestibular schwannoma

A non-cancerous (benign) tumor of the sheath surrounding the vestibular nerve.

The vestibular nerve connects the inner ear to the brain; and is responsible for balance and hearing.

Vestibular schwannomas usually affect both ears, and can lead to ear ringing (tinnitus), hearing loss, and difficulty maintaining balance.

Peripheral schwannomas

Nerve sheath tumors arising from other nerves, such as the nerves of the head and face (cranial nerves).

Meningioma

A type of non cancerous (benign) tumour that originates from the covering of the brain and spinal cord (meninges). It can cause compression to nearby structures (brain, nerves, eye).

Other Symptoms

Other types of brain and spine tumors (E.g.: Gliomas, Ependymomas).

Clouding of the eye lens (juvenile cortical cataracts).

Neurofibromatosis Type 2 is diagnosed through a combination of clinical and genetic (molecular) criteria.

The presence of an affected parent or family member with Neurofibromatosis significantly increases the likelihood of diagnosis.

In the case that multiple suggestive symptoms of Neurofibromatosis Type 2 are present, Single Gene Testing may be done to confirm the disease.

Neurofibromatosis Type 2 is inherited in an autosomal dominant manner.

“Autosomal” means that the gene in question is located on one of the numbered, or non-sex chromosomes.

“Dominant” inheritance means one gene in a pair being abnormal is enough to cause the disease.

The risk of reoccurrence of Neurofibromatosis Type 2 in other siblings:

About 50% of individuals have an affected parent. If one parent is affected, other siblings have a 50% chance of being affected with Neurofibromatosis Type 2.

About 50% of individuals have the disease because of a new (de novo) mutation. If the child has Neurofibromatosis Type 2 due to a new mutation and have no other affected family members, the risk of other siblings being affected is less than 1%.

The estimated incidence of Neurofibromatosis Type 2 is 1 in every 50,000 live births, across different ethnic groups. The incidence among males and females is similar.

A team of healthcare specialists should be involved in care, including:

• Brain and nerve specialist (neurologist).
• Hearing specialist (audiologist).
• Brain and spine surgeon (neurosurgeon).
• Tumor surgeon (surgical oncologist).
• Eye specialist (ophthalmologist).
• Genetic counselor.
• Learning disability specialist.

Written by: Khawla Ben Yahia, MBBS.

Reviewed by: Dr. Ayman W. El-Hattab, MD, FAAP, FACMG

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5. NORD. "NF2-Related Schwannomatosis." National Organization for Rare Disorders (2023).
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