Neurofibromatosis type 1 (NF1) is a genetic condition that causes tumors to grow along nerves. It is usually diagnosed during childhood, and signs are often noticeable at birth or shortly afterward and almost always by age 10. The severity of the condition can vary considerably from person to person. Some of the signs and symptoms of NF1 include:

• Flat, light brown spots on the skin (cafe au lait spots). Having more than six cafe au lait spots suggests NF1.
• Soft, non-cancerous tumors on or under the skin (neurofibromas) .
• Clusters of freckles in unusual places – such as the armpits, groin, and under the breast.
• Larger than average head size.
• Learning disabilities, attention-deficit/hyperactivity disorder (ADHD), and speech delay.
• Curvature of the spine (scoliosis) that may need bracing or surgery.
• Vision problems.
• Problems with the bones, such as decreased bone mineral density, which increases the risk of weak bones (osteoporosis) .
• Problems during times of hormonal change.
• Increased risk of other forms of cancer, such as breast cancer, leukemia, and malignant peripheral nerve sheath tumors.

NF1 is caused by a faulty gene called NF1, which regulates the production of a protein known as neurofibromin, which is thought to function as a tumor suppressor. In about half of all cases of NF1, the faulty gene is passed from a parent to their child. However, in about 50 percent of individuals with NF1, the disorder results from spontaneous (sporadic) changes in the NF1 gene that occur for unknown reasons. There is no cure for NF1, but symptoms can be evaluated and addressed.