An inherited disease where nerve tissue grows abnormally and can cause serious damage to surrounding nerves resulting in loss of function, pain and numbness. There are 3 different types of neurofibromatosis (NF) with NF-1 being the most common, the other types are referred to as NF-2 and Schwannomatosis (named for the type of cell that grows abnormally). About 3-15% of people with NF-1 will have a malignant tumor resulting in death. However, usually the tumors are not fatal.