Neurofibromatosis Type 1 (NF1)

Symptoms and Causes

What causes neurofibromatosis type 1 (NF1)?

Neurofibromatosis is generally an inherited disorder of the autosomal dominant kind. This means that only one copy of a mutant gene is needed to produce the condition, and patients have a 50:50 chance of their children getting the disorder.

Neurofibromatosis also can be caused by spontaneous mutation (change) in up to 50% of cases. Once the change in genes happens, it can be passed on to the next generation.

What are some signs and symptoms of neurofibromatosis type 1 (NF1)?

Common signs and symptoms of NF1 include:

• Café-au-lait spots (also called café-au-lait macules): These are flat patches of light brown or coffee-colored skin. Initially, you might see them on your infant and think the spots are freckles. The spots may get larger and more numerous during your child's first few years of life (up to about 7 years old). A child with NF1 is likely to have at least six or more of these spots that are larger than freckles. The spots themselves are not painful. Even people who don’t have neurofibromatosis can have one or two café-au-lait spots that are benign (non-cancerous).
• Lisch nodules: These are small non-cancerous growths located on the iris (the colored part) of the eyes. Lisch nodules don’t cause problems with vision, but tumors might later develop in the eye. These tumors are called optic gliomas. They may or may not affect vision.
• Neurofibromas: These are non-cancerous tumors that are located mostly under the skin. Neurofibromas may also grow on nerves. There is a certain type of neurofibroma called a plexiform neurofibroma that comes with a 5% to 10% risk of developing a malignant peripheral nerve sheath tumor (MPNST).
• High blood pressure (hypertension).
• Short stature (height).
• Macrocephaly (an unusually big head).
• Bone abnormalities, such as scoliosis (a curved spine) or bowing (curving) of leg bones.
• Learning disabilities.
• Attention deficit hyperactivity disorder (ADHD).
• Seizures.
• Speech problems.
• Many freckles under the armpit or in the groin region — called axillary or inguinal freckling.

There may be other complications associated with NF1, including vascular (blood vessel) conditions that affect the central and peripheral nervous systems. One condition in particular is one that involves arterial narrowing called Moyamoya disease.