Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Neurofibromatosis type I (NF-1), formerly known as von Recklinghausen disease after the researcher who first documented the disorder, is a human genetic disorder. It is possibly the most common inherited disorder caused by a single gene. NF-1 is not to be confused with Proteus Syndrome (the syndrome which may have affected The Elephant Man), but rather is a separate disorder. NF-1 is a tumor disorder that is caused by the malfunction of a gene on chromosome 17, that is responsible for control of cell division. NF1 causes non cancerous lumps. NF2 often comes with scoliosis (curvature of the spine), cafe au lait spots, learning difficulties, eye problems and epilepsy. NF-1 is caused by a mutation of a gene on the long arm of chromosome 17 which encodes a protein known as neurofibromin (not to be confused with the disorder itself) which plays a role in intracellular signaling. The neurofibromin is a negative regulator of the Ras oncogene. The mutant gene is transmitted with an autosomal dominant pattern of inheritance, but up to 50% of NF-1 cases arise due to spontaneous mutation. The incidence of NF-1 is about 1 in 3500 live births.