Neurofibromatosis Type 1 (NF1)
Synonyms of Neurofibromatosis Type 1 (NF1)
- neurofibroma, multiple
- neurofibromatosis-pheochromocytoma-duodenal carcinoid syndrome
- peripheral neurofibromatosis
- Recklinghausen's phakomatosis
- Von Recklinghausen's disease
- Von Recklinghausen's neurofibromatosis
Subdivisions of Neurofibromatosis Type 1 (NF1)
- segmental neurofibromatosis
Neurofibromatosis type 1 (NF1), also called von Recklinghausen's disease, is a rare genetic disorder characterized by the development of multiple noncancerous (benign) tumors of nerves and skin (neurofibromas) and areas of abnormally decreased or increased coloration (hypo- or hyperpigmentation) of the skin. Areas of abnormal pigmentation typically include pale tan or light brown discolorations (cafe-au-lait spots) on the skin of the trunk and other regions as well as freckling, particularly under the arms (axillary) and in the groin (inguinal) area. Such abnormalities of skin pigmentation are often evident by one year of age and tend to increase in size and number over time.
At birth or early childhood, affected individuals may have relatively large benign tumors that consist of bundles of nerves (plexiform neurofibromas). Individuals with NF1 may also develop benign tumor-like nodules of the colored regions of the eyes (Lisch nodules) or tumors of the optic nerves (second cranial nerves), which transmit nerve impulses from the innermost, nerve-rich membrane of the eyes (retinas) to the brain. More rarely, affected individuals may develop certain malignant (cancerous) tumors.
NF1 may also be characterized by unusual largeness of the head (macrocephaly) and relatively short stature. Additional abnormalities may also be present, such as episodes of uncontrolled electrical activity in the brain (seizures); learning disabilities; speech difficulties; abnormally increased activity (hyperactivity); and skeletal malformations, including progressive curvature of the spine (scoliosis), bowing of the lower legs, and improper development of certain bones. In individuals with NF1, associated symptoms and findings may vary greatly in range and severity from case to case. Most people with NF1 have normal intelligence but learning disabilities appear in about 50% of children with NF1.
NF1 is caused by changes (mutations) of a relatively large gene on the long arm (q) of chromosome 17 (17q11.2). The gene regulates the production of a protein known as neurofibromin, which is thought to function as a tumor suppressor. In about 50 percent of individuals with NF1, the disorder results from spontaneous (sporadic) mutations of the gene that occur for unknown reasons. In others with the disorder, NF1 is inherited as an autosomal dominant trait.
The name "neurofibromatosis" is sometimes used generally to describe NF1 as well as a second, distinct form of NF known as neurofibromatosis Type II (NF2). Also an autosomal dominant disorder, NF2 is primarily characterized by benign tumors of both acoustic nerves, leading to progressive hearing loss. The auditory nerves (eight cranial nerves) transmit nerve impulses from the inner ear to the brain.
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