What are Neurofibromatosis Type 1 (NF1) and Neurofibromatosis Type 2 (NF2)?
The neurofibromatoses are a part of a group of conditions known as neurocutaneous disorders that affect the skin and the nervous system. These types of disorders are caused by abnormal cell multiplication, which results in the formation of tumors all over the body. In particular, these tumors can grow on nerves, causing problems with the skin, bones, eyes, and elsewhere.
There are two main subtypes of neurofibromatoses: Neurofibromatosis type 1 (NF1), which accounts for about 90% of all cases of neurofibromatosis, and Neurofibromatosis type 2 (NF2), which is much less common, especially in children. Neurofibromatosis is generally an inherited disorder (autosomal dominant), but it 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.
Neurofibromatosis 1 (or NF1) occurs in about one in 3,000 to 4,000 births; NF2 occurs much less often (1 in 25,000 live births).
What are some symptoms of neurofibromatosis Type 1 (NF1)?
Common Signs of NF:
- Café-au-lait spots (also called café-au-lait macules): These are flat patches of light brown or coffee-colored skin. Initially, they might be present on an infant and look like freckles, but may get larger and more numerous during a 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, and people who do not 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 do not 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. In a special type of neurofibroma (called a plexiform neurofibroma), there is a 5-10% 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 or tibial bowing.
- Learning disabilities.
- Attention deficit hyperactivity disorder (ADHD).
- 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--in particular, arterial narrowing called Moyamoya disease.