Approximately 25% of patients will require corrective surgery.Skeletal muscle weakness and motor control deficits
Deficits in motor function in NF-1 have been long recognised and have been historically attributed to nerve dysfunction. In recent years however, studies suggest NF-1 is associated with a primary problem in muscle function (myopathy).Clinical findings in people with NF-1 include:

Reduced skeletal muscle size
Reduced exercise capacity
Muscle weakness (The most recent study reports between 30–50% reduced upper and lower limb muscle strength in NF-1 children compare with matched controls).Studies in genetically modified mice have thus far confirmed that the NF1 gene is vital for normal muscle development and metabolism. Knockout of the NF1 gene in muscle results in deregulated lipid metabolism and muscle weakness.NF-1 is a disease in the RASopathy family of diseases, which include Costello Syndrome, Noonan Syndrome, and Cardiofaciocutaneous syndrome. The RASopathies also present with skeletal muscle weakness. It is likely that impaired muscle function in these disorders is linked to altered Ras/MAPK signalling, however, the precise molecular mechanisms remain unknown. Facial bones and limbs
Bowing of a long bone with a tendency to fracture and not heal, yielding a pseudarthrosis. The most common bone to be affected is the tibia, causing congenital pseudarthrosis of the tibia or CPT. CPT occurs in 2–4% of individuals with NF-1. Treatment includes limb amputation or correction by Ilizarov method as a limb-sparing technique. Malformation of the facial bones or of the eye sockets (lambdoid suture defects, sphenoid dysplasia)
Unilateral overgrowth of a limb.
For example, some individuals have no symptoms, while others may have a manifestation that is rapidly more progressive and severe. For many NF-1 patients, a primary concern is the disfigurement caused by cutaneous/dermal neurofibromas, pigmented lesions, and the occasional limb abnormalities. However, there are many more severe complications caused by NF-1 like increased cancer risk, a plexiform neurofibroma has a 10-15% chance of developing into a MPNST (Malignant Peripheral Nerve Sheath Tumour) . Many NF patients live perfectly normal and uninterrupted lives. Epidemiology
NF-1 is estimated to affect around 25,000 people in the UK. See also
Neurofibromatosis type II

References
External links

Friedman, J. M. (1993). "Neurofibromatosis 1". GeneReviews®. University of Washington, Seattle. PMID 20301288. Legius, Eric; Stevenson, David (1993). "Legius Syndrome". GeneReviews®. University of Washington, Seattle. PMID 20945555.