Neurofibromatosis type 1 (NF1) is caused by a change (mutation or variant) in a gene. Most often, it’s diagnosed during childhood. NF1 is among the most common genetic disorders. It affects about 1 in every 3,000 people.

What causes neurofibromatosis Type 1 (NF1)?

NF1 is caused by a genetic mutation on chromosome 17. This mutation can be inherited. It can be passed on from parent to child.

About half of the people who have NF1 inherited it from a parent. If you have NF1, there’s as much as a 50 percent chance you will pass it on to your child. That means the chance your child will inherit NF1 from you are the same as the chance they will not inherit it.

NF1 also can happen in people who did not inherit the gene mutation from their parents.

Neurofibromatosis type 1 (NF1) symptoms & diagnosis

What are the signs and symptoms of NF1?

NF1 can cause many symptoms and problems. Some are bad enough to harm you. NF1 makes it more likely you will get certain types of these tumors.

Symptoms that are tumors
 

Dermal (skin) neurofibromas (NOOR-oh-fy-BROH-muhs). This is not cancer. It is the most common type of NF1 tumor. It’s a type of peripheral nerve tumor that grows on or under the skin. Some people have many tumors, or just a few. They can be small or big.

Malignant peripheral nerve sheath tumors (MPNST). This rare tumor is cancer. It’s cancer of the cells that form the sheath (protective covering) around peripheral nerves. These are the nerves outside of the central nervous system. MPNST grow fast and can spread to other parts of the body.

Plexiform neurofibromas. This rare tumor is not cancer. But it can turn into an aggressive cancer called malignant peripheral nerve sheath tumor (MPNST). Plexiform neurofibromas often affect the spine and the peripheral nerve sheath. They can grow big. Not everyone with NF1 will get plexiform neurofibromas. 

Gliomas.  A glioma is a type of tumor that starts in the glial cells. The glial cells surround and support the neurons in the brain and other parts of the nervous system. Gliomas are one of the most common types of primary brain tumors. They can be low grade (slow-growing) or rare high grade (fast-growing) tumors.

Sometimes low-grade gliomas slowly change into high-grade gliomas. Out of every 100 people with NF1, about 1 or 2 will get high grade gliomas.

Gastrointestinal stromal tumors (GIST). A GIST is a rare cancer. It’s a type of soft tissue sarcoma (sar-KOH-muh) that often starts in the abdomen (belly).

Pheochromocytoma (FEE-oh-KROH-moh-sy-TOH-muh). This type of tumor starts in the center of the adrenal gland. It causes too much adrenaline. These tumors can cause hypertension (high blood pressure).

Rhabdomyosarcoma (RAB-doh-MY-oh-sar-KOH-muh). This is a rare sarcoma, a type of cancer that starts in soft tissues. Rhabdomyosarcoma starts in the muscles and can cause pain and swelling.

Breast cancer is when cells in the breast grow and multiply in an abnormal (not normal) way.  Breast cancer can happen if the genes in a cell that control cell growth no longer work well. The cells keep growing and can form a tumor.

Juvenile myelomonocytic leukemia (JMML). JMML is a rare blood cancer. It most often affects infants and toddlers. It starts in the bone marrow.  A genetic change in stem cells causes them to make too many white blood cells called monocytes.

Symptoms that are not tumors

NF1 can cause signs that are not tumors. Symptoms can include:

• Learning disability or attention deficit (hard to pay attention)
• Vision loss
• Stroke
• Hypertension
• Dermal (skin) lesions
• Bone problems, such as too little vitamin D and scoliosis
• Feeling weak, numb, or both

It’s important to get cancer screenings. These tests can help find symptoms of NF1, such as breast cancer, leukemia, pheochromocytoma, and GIST.

How is NF1 diagnosed?

An NF1 diagnosis is based on whether you show signs or symptoms of neurofibromatosis. Doctors will look for:

• Cognitive problems (trouble with memory and thinking)
• Ophthalmological (aaf-thal-maa-LUH-jee-cal) problems (trouble with eyes)
• Neurological symptoms (problems with the nervous system)
• Skin changes (spots that are not normal, or bumps)

Symptoms can include learning disability, attention deficit, vision loss, and feeling weak, numb, or both.

Often the first step in diagnosing NF1 is a physical exam to check for these signs. Your doctor will also review your personal and family health history.

You must have at least 2 of these signs to be diagnosed with NF1:

• 6 or more flat café au lait (light brown) spots on the skin
• Freckles in the underarm or groin area
• 2 or more dermal neurofibromas, which are small lumps or bumps that grow on or under the skin. Or, you have at least 1 plexiform neurofibroma (a very large neurofibroma)
• An optic pathway glioma. This is a tumor that grows in the cells around the optic nerve.
• 2 or more or either of these:
• Lisch nodules (harmless dots in the colored part of the eye)
• Choroidal abnormalities. Something is not normal in a layer of blood vessels in the eye called the choroid.
• Bony abnormalities, such as tibial pseudoarthrosis, sphenoid wing dysplasia, and severe (very bad) scoliosis.
• An NF1 gene mutation
• At least 1 parent has NF1

Tests to look for NF1

You may need an eye exam to look for Lisch nodules or choroidal abnormalities.

You may need imaging tests to check for tumors or bone problems.

Sometimes you may need a genetic test, which can help us make the right diagnosis.

Neurofibromatosis type 1 (NF1) treatment

NF1 does not affect everyone the same way, so treatments are different. For most people, the care plan involves monitoring or removing tumors. We also manage your pain, neurologic problems, and other symptoms.

MSK doctors use the latest imaging technology to screen for NF1 tumors. When treatment is needed, we will make a treatment plan based on the type of tumor.

Our neurosurgeons are experts in removing complex tumors. The tumor may be in a place that’s hard to reach, or in a delicate part of the body. MSK experts often can remove tumors that other hospitals consider too complex to remove. 

MSK surgeons are experts in surgery methods that do less harm to your body. For some people, we may recommend minimally invasive surgery. This method does less harm to your body because it’s done with small incisions (cuts).

MSK surgeons use these minimally invasive methods to diagnose and treat tumors and cancers. There are 2 types of minimally invasive surgery. They’re called laparoscopic surgery and robot-assisted surgery.

Benefits of minimally invasive surgery include:

• Less loss of blood
• A shorter hospital stay
• A faster recovery
• Less scarring
• Less risk of infection
• Fewer complications (problems) during and after surgery

MSK offers children and adults expert care for NF1 and the tumors linked to this disease. We will support your family as you make decisions about a treatment plan.

NF1 Adult Glioma Registry

We need your help in the fight against NF1. MSK is a leader in researching how to prevent and treat problems related to NF1. We invite you to join our NF1 Adult Glioma Registry. It’s a database MSK made to research and help adults with gliomas related to NF1.

Through this registry, we invite you to join and share information about your brain tumor history. We hope you will help this important research about NF1 and gliomas.

Anyone with NF1 related glioma can join, whether or not you’re treated at MSK. It’s voluntary, and your choice to join the registry.

Your health information will be encrypted (kept safe). It will be de-identified, which means nothing will connect your name to your health information.

By looking at the data (information) of many people with brain tumors, researchers can look for patterns. Their research may lead to new therapies and treatments that can be tested in clinical trials. By helping us now, you’re helping future research about NF1 and gliomas.

Watch our video to learn more.