Neurofibromatosis type 1, or NF1, is the most common form of NF. NF is a general term for several genetic conditions that cause tumors to grow on nerves. Currently, we group NF1, NF2-related schwannomatosis (NF2-SWN), and other schwannomatosis (SWN) under this term.

NF1 is the most common form of NF and occurs in approximately 1 in every 2,500 births. Many people inherit NF1 from a parent because an affected parent has a 50% chance of passing it on. People can be born with NF1 without inheriting it through what is called a genetic variant. They then may pass NF1. NF1 does not “skip” generations.

NF1 is often diagnosed in childhood. However, some people may be diagnosed later if they have mild symptoms. Also, some healthcare providers who are not familiar with NF1 may miss the early signs of the condition.

Characteristic features of NF1 may include café-au-lait spots (pigmented birthmarks), freckling in the armpits or groin area, bone abnormalities, learning disabilities, and neurofibromas. Cutaneous neurofibromas are benign tumors that often occur on or in the skin. A plexiform neurofibroma is a more extensive and complex growth that involves multiple nerves and can occur deeper in the body. Approximately 10% of plexiform neurofibromas may become malignant. Neurofibromas may cause disfigurement, pain, and other symptoms. People with NF1 may also develop other types of tumors including optic nerve gliomas which can lead to vision problems.

The severity of the condition can vary widely between individuals, even within families.