Neurofibromatosis is a genetic disease that mostly affects the development of nerve cells. Also called NF for short, neurofibromatosis has two forms, NF1 (more common) and NF 2 (less common). As a story from a Dallas TV station notes, neurofibromatosis is more common than you might think, affecting one in 3,000 people.
The U.S. government's National Institute of Neurological Disorders and Stroke (NINDS) has a neurofibromatosis information page that explains the disease in plain English. According to this page, "These disorders cause tumors to grow on nerves and produce other abnormalities such as skin changes and bone deformities." NINDS also has a handy neurofibromatosis fact sheet. Symptoms of NF1 are often noticeable at birth or in infancy, usually in the appearance of the skin.
You can find information and support for neurofibromatosis at the Web site of the Neurofibromatosis, Inc. NINDS also has an article on the proceedings of a workshop on neurofibromatosis in children, addressing basic and clinical research, animal models, treatment, and more.