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Laura Klesse, M.D., Ph.D. Answers Questions On Neurofibromatosis

Laura Klesse, M.D., Ph.D. Answers Questions On: Neurofibromatosis

What are the differences in the types of neurofibromatosis?

Neurofibromatosis type 1 is a cancer predisposition that affects one in 2,500 people worldwide, so it’s pretty common. About half the time, there’s a clear family history. The other half, it’s a new genetic change. It’s a change in chromosome 17 that puts people at risk.

People born with six or more birthmarks should potentially get screened for neurofibromatosis. The birthmarks put you at risk for the development of tumors attached to any nerve.

Neurofibromatosis type 2 is caused by mutations in the NF2 gene. It can also run in families, but it’s less common, affecting about one in 25,000 people worldwide. It’s a predisposition that puts you at risk for tumors along your hearing nerves. Almost everyone who is diagnosed with NF2 will get tumors on both hearing nerves and will eventually go deaf. They’re also at risk for a number of other brain and spine tumors.

The third type of neurofibromatosis is schwannomatosis. It is genetically and clinically distinct from NF1 and NF2. It affects one in about 40,000 individuals worldwide. It tends to put people at risk for small tumors that develop along the nerves and bring intractable pain that is difficult to manage.

Are the tumors associated with neurofibromatosis type 1 usually benign or malignant?

Most of them are benign, but there is a clear increased risk of malignant cancer. About 10 percent of patients will get a true, high-risk sarcoma. They’re also at increased risk for malignant brain tumors and breast cancer. That said, the benign tumors can be life-threatening if they grow in places near the airway or near the eyes. These big overgrowths of support cells near a group of nerves is called a plexiform neurofibroma. About 20 to 25 percent of kids with NF will develop one of these tumors along the optic nerve, and it can take their sight.

When neurofibromatosis runs in families, do they usually know about it?

Most do, but there are still some who do not know until their child is diagnosed. The reason a lot of people have never heard of NF until they or their child is diagnosed with it is because most people with NF lead normal lives. If they know it runs in their family, it’s usually because family members have obvious birthmarks and have experienced some neurofibromas.