Neurofibromatosis Type 1

Definition

Neurofibromatosis is a genetic problem that causes tumors to grow in the nervous system. Tumors form in the nerves or the tissue around the nerves, called the myelin sheath. There are 3 types—neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis. They are grouped by the genes that are affected.

This articles discusses NF1, the most common type. It affects the nerves outside the brain and spinal cord. These are called peripheral nerves.

The Nervous System.

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Causes

NF1 is caused by a change in a gene that normally makes proteins to control growth in the nerves. When the gene is not working the proteins cannot control growth. Then tumors can form.

The abnormal gene is often passed to a person from a parent. A person with this form of NF has a 50% chance of passing the abnormal gene to each child. Any parents, children, and siblings of a person who has NF could be at risk for it.

The gene change can also happen in a person who has no family history of NF.

Risk Factors

A person is more at risk for NF if they have a family member with it.

Symptoms

Most symptoms start by age 10. NF1 may cause:

• Light brown spots (called café au lait spots) on the skin
• Freckles in the armpits or groin
• Larger than normal head size in children
• Shorter than normal stature in children
• Problems with how the spine, skull bones, or shin bones grow

Other medical issues that are linked to NF1 include:

• Learning issues such as attention deficit hyperactivity disorder (ADHD) or other mental problems
• Seizures
• Headaches
• Problems with the heart or blood vessels
• High blood pressure

Diagnosis

You will be asked about symptoms and health history. A physical exam will be done. It may take a few years before NF1 is diagnosed. NF1 may be suspected if there is a history of:

• Neurofibromas (tumors that grow on a nerve or nerve tissue)— these rarely happen before puberty, but they can start growing fast and spread through the body
• Growths on the iris of the eye (called Lisch nodules or hamartomas)
• Tumor on the optic nerve that may change vision (optic nerve gliomas)

Images may be taken of your nerves and brain. This can be done with an MRI scan. Samples of tumors may also be removed and sent for a biopsy.

Genetic testing may be advised for families with a history of NF. It may be possible to use amniocentesis or chorionic villus sampling to diagnose a fetus with NF before birth.

You may be asked to see other doctors who can look for tumors in the nervous system.

Treatment

The goal of treatment is to control symptoms the tumors cause. There are no treatments to stop these tumors from growing. Treatment may not be needed since these tumors are rarely cancerous. They often grow slowly and may not cause problems. Regular exams are advised to check for new tumors or symptoms.

Surgery may be done to remove tumors that hurt or bother someone. Medicines and therapies may also be needed to manage other symptoms such as seizures and learning problems.

Prevention

NF1 cannot be prevented.