Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders affecting 1 in 3500 people. NF1 is a complex neurocutaneous disorder with an increased susceptibility to develop both benign and malignant tumors but with a wide spectrum of inter and intrafamilial clinical variability. The most prominent clinical hallmarks of the disorder are café-au-lait macules, neurofibromas, Lisch nodules of the iris, and axillary freckling. Other clinical manifestations are abnormalities of the cardiovascular, gastrointestinal, renal, and endocrine systems, facial and body disfigurement, cognitive deficit, and malignancies of the peripheral nerve sheath and central nervous system. About 25% of people with neurofibromatosis type 1 develop one or more of these clinical complications, which together cause significant morbidity and mortality. The tumors that occur in neurofibromatosis type 1 are dermal and plexiform neurofibromas, optic gliomas, malignant peripheral nerve sheath tumors, pheochromocytomas, and rhabdomyosarcomas. Children with neurofibromatosis type 1 have an increased risk of developing myeloid disease, particularly juvenile chronic myeloid leukemia.
Neurofibromatosis type I is caused by mutation in the neurofibromin gene, NF1.