Overview

What is neurofibromatosis type 1?

Neurofibromatosis type 1 (NF1) is a hereditary condition commonly associated with multiple café-au-lait spots on the skin. Café-au-lait spots are light brown in color, like the color of “coffee with milk.” About 10% to 25% of the general population has café-au-lait spots; NF1 is suspected when a person has six or more. People with NF1 also tend to develop varying numbers of neurofibromas (benign [noncancerous] tumors of the covering of the nerves). Neurofibromas are often seen as raised bumps on the skin and can occur anywhere on the body. While these skin changes do not have serious medical consequences, they can affect a person’s appearance. Plexiform neurofibromas (which form under the skin or deeper in the body) are also benign tumors. However, these can grow quite large and can cause significant medical problems, and can affect the structure of nearby bone, skin, and muscle.

What causes NF1?

NF1 is a genetic condition. This means that the cancer risk and other features of NF1 can be passed from generation to generation in a family. The gene commonly associated with NF1 is also called NF1. A mutation (alteration) in the NF1 gene gives a person an increased risk of developing the various symptoms of NF1, including cancer. Most people with NF1 have a mutation in the NF1 gene. It is now believed that mutation in other genes may also produce multiple nerve tumors. In particular, a different tumor suppressor gene called INI 1 may cause multiple schwannomas on nerves in some patients. This is a different disease, however, from NF1 since the hallmark of NF1 is neurofibromas rather than schwannomas (both are tumors that grow on nerves, but they have different causes). Research is ongoing to learn more about NF1 and other diseases causing nerve tumors.

How is NF1 inherited?

Normally, every cell has two copies of each gene: one inherited from the mother and one inherited from the father. NF1 follows an autosomal dominant inheritance pattern, in which a mutation happens in only one copy of the gene. This means that a parent with a gene mutation may pass along a copy of their normal gene or a copy of the gene with the mutation. Therefore, a child who has a parent with a mutation has a 50% chance of inheriting that mutation. A brother, sister, or parent of a person who has a mutation also has a 50% chance of having the same mutation.

What are the estimated cancer risks associated with NF1?

The lifetime risk of cancer in a person with NF1 is estimated to be about 7%.

What are the screening options for NF1?

Suggested screening for people with NF1 or at risk for NF1 includes:

• Yearly examination by a doctor familiar with NF1
• Yearly eye examinations, beginning in childhood (may become less frequent in adulthood)
• Yearly blood pressure monitoring
• Developmental assessments in childhood, as needed
• Other evaluations (such as imaging scans, like CT scan or MRI), as needed for symptoms

Screening recommendations may change over time as new technologies are developed and more is learned about NF1. It is important to talk with your doctor about appropriate screening tests. In some areas, comprehensive NF1 clinics may be available to help with coordination of medical care.

What are ways of treating NF1?

Usually the recommended treatment approach for tumors associated with NF1 is to watch them for growth or for development of associated symptoms like pain or weakness. This is called watchful waiting, watch and wait, or active surveillance. If symptoms develop over time, then surgery is done to remove the tumors. It is usually possible to remove tumors growing on or from nerves, and to preserve the nerve involved, unless the tumor is plexiform. Such plexiform tumors are more diffuse and often infiltrate the nerve, which makes it harder to remove the tumor without hurting the nerve. Cancerous tumors may be treated with chemotherapy, radiation therapy, or a combination of both. Clinical trials (research studies) for neurofibromatosis are ongoing and currently focus on drugs that affect the ras signaling pathway inside the tumor cell; problems in the ras pathway are common in tumors in NF1.