neurofibromatosis type 1

neurofibromatosis type 1 A genetic disorder that is characterized by a number of skin characteristics, including multiple café au lait (coffee with milk) spots, multiple benign tumors called neurofibromas on the skin, plexiform neurofibromas (thick and misshapen nerves due to the abnormal growth of cells and tissues that cover the nerve), and freckles in the armpit and groin. Abbreviated NF1. The café au lait spots increase in number and size with age. The skin neurofibromas appear later, usually in the second decade of life. Patients with NF1 have an increased risk of scoliosis, optic gliomas (benign tumors on the optic nerve), epilepsy, and learning disabilities. The risk of malignant degeneration of neurofibromas is lower than 5 percent. NF1 is inherited in an autosomal dominant manner and is due to mutation of the NF1 gene on chromosome 17 that encodes a protein called neurofibromin. Half of cases are due to new mutations in the NF1 gene. Prenatal testing is available. Also known as von Recklinghausen disease.