Neurofibromin protein consists of 2839 amino acids and weighs about 319 kDa. It is produced in many cell types, such as nerve cells and specialized cells called oligodendrocytes and Schwann cells that surround nerves. It acts as a tumor suppressor protein and function as a negative regulator by turning off RAS protein that stimulates cell growth and division; thereby, preventing cell overgrowth. Defects in neurofibromin protein cause an autosomal dominant condition called neurofibromatosis type I (NF1), characterized by cafe-au-lait spots, axillary freckling, Lisch nodules of the iris, multiple neurofibromas, tibial pseudarthrosis and a predisposition to certain benign and malignant tumors of the central and peripheral nervous system.
The neurofibromin 1 (NF1) gene is located at chromosome 17q11.2, where it spans a length of about 287 kb of genomic DNA, and contains 58 exons. Several mutations have been identified in this gene causing neurofibromatosis type 1. Many of these mutations result in a truncated protein while some of them cause amino acid substitutions. The mutated protein cannot perform its normal job of inhibiting cell division, causing loss of neurofibromin, which allows noncancerous tumors called neurofibromas to form.