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Neurofibromatosis Type 1

What Is Neurofibromatosis Type 1?

Neurofibromatosis type 1 (NF1) is a genetic condition. It causes benign (not cancerous) tumors to grow in and under the skin, often with bone, hormone, and other problems.

Most kids with NF1 have mild symptoms that don't limit what they can do.

There are two main types of neurofibromatosis (nur-oh-fye-broh-muh-TOE-sis):

  • NF1: The most common type, it affects 1 of every 3,000 births.
  • Neurofibromatosis type 2 (NF2): NF2 is much rarer. It affects about 1 in 25,000 births.

They're very different conditions. NF1 can never become NF2 or the other way around, and a person usually has only one type of neurofibromatosis.

A third type of NF (called schwannomatosis) is very rare. Most people with this type don't have symptoms until they're adults.

What Are the Signs & Symptoms of Neurofibromatosis Type 1?

Most newborns with neurofibromatosis type 1 have no symptoms, but some have curved lower leg bones.

By their first birthday, most children with NF1 have several skin spots, called café-au-lait ("coffee with milk") spots because of their color. Café-au-lait spots are:

  • darker than surrounding skin
  • more than 1/4-inch (5 millimeters) across

Children with NF1 may be slower to walk, talk, and reach other milestones than most kids. They also may have:

  • bumps in and under the skin (called neurofibromas)
  • a head that looks large for the body
  • headaches
  • trouble learning
  • attention problems and hyperactivity
  • a shorter height than most children the same age
  • side-to-side curves in the backbone (scoliosis)
  • curving, thinning, or weakness of the forearms or lower leg bones
  • freckles in their armpits or in the crease between the belly and hip (groin)

Neurofibromas (ner-oh-fye-BROH-muz) can cause appearance problems and be painful. Very large neurofibromas (called plexiform neurofibroma) may turn into cancer.

The symptoms of NF1 are mild in some children, but severe in others.

What Causes Neurofibromatosis Type 1?

NF1 and NF2 are part of a group of rare conditions called RASopathies (raz-OP-uh-thees). These happen when there's a problem in the way cells communicate in one of the body's pathways.

Children with neurofibromatosis type 1 have cells that don't make neurofibromin as they should. Neurofibromin is a protein that acts like a brake to stop the RAS pathway and keep cells from growing out of control.

Without working neurofibromin, the cells:

  • can't shut down the RAS pathway
  • grow out of control, leading to tumors and other problems

This happens because of a change (mutation) in a gene called NF1.

Depending on when the DNA change happened, NF1 can be:

  • Classic: The NF1 gene change affects all cells in the body.
  • Mosaic: The body has a mix of cells with and without the NF1 gene change.
  • Segmental: The NF1 symptoms are in one part of the body.

Sometimes, NF1 runs in families. A parent who has it has a 50% chance of passing it to a child. Other times, the change is "spontaneous." This means that a child has the condition but the parents do not. This is called a new mutation.

How Is Neurofibromatosis Type 1 Diagnosed?

NF1 may be diagnosed before or at birth using genetic (DNA) tests. A doctor usually suggests genetic testing for NF1 if:

  • a parent or sibling of an unborn baby is known to have NF1
  • a newborn shows signs of NF1

Most children with NF1 are diagnosed only after several café-au-lait spots appear. A doctor usually will:

  • ask about the child's symptoms and whether family members have similar symptoms
  • consider NF1 and other conditions that can cause café-au-lait spots

The doctor will do an exam and may work with a team of specialists who diagnose and treat children with NF1, including:

  • an ophthalmologist, who will check for:
    • a tumor (an optic glioma) on the nerve from the eye to the brain
    • small spots (called Lisch nodules) on the colored part (iris) of the eye
  • a geneticist who will test for the gene changes that can cause NF1

When doctors suspect a child has NF1, they sometimes look for brain, bone, and other problems using:

  • blood tests
  • X-rays

Because children with NF1 get more signs and symptoms as they grow, the diagnosis may not be made right away. Almost all kids with the condition are diagnosed by the time they're 8 years old.

How Is Neurofibromatosis Type 1 Treated?

There's no cure for NF1, but treatment can make it easier for a child to live with its symptoms.

Children with NF1 are cared for by a team that includes specialists in:

  • neurology: for problems with the nerves, brain, and spinal cord
  • plastic surgery: to treat appearance concerns
  • oncology: to treat or remove tumors
  • ophthalmology: for eye problems
  • orthopedics: for bone problems
  • endocrinology: for hormone problems
  • psychiatry and behavioral health: to help with behavior and attention issues

What Else Should I Know?

Most children with NF1 have mild symptoms, and live full, typical lives. A child with NF1 needs regular checkups so doctors can look for:

  • eye problems
  • blood pressure problems
  • new tumors
  • tumor growth
  • scoliosis
  • learning problems

Research continues into better treatments for people with NF. Ask if your child might be a candidate for a clinical trial that's testing a new treatment option.

Reviewed by: Karen W. Gripp, MD
Date Reviewed: Jul 22, 2022

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