several symptoms that have little more than cosmetic effects. The other 20% have severe cases with several symptoms that affect the person's quality of life. Even in this last group, symptoms are rarely life-threatening. Signs and symptoms The following is a list of conditions and complications associated with NF-1, and, where available, age range of onset and progressive development, occurrence percentage of NF-1 population, method of earliest diagnosis, and treatments and related medical specialties. The progression of the condition is roughly as follows: Congenital musculoskeletal disorders may or may not be present Cutaneous conditions may be observed in early infancy Small tumors may arise in the retina which can eventually lead to blindness. Also, Lisch Nodules may grow on the iris, but these are harmless. Learning disabilities may arise in preschool children Neurofibromas may occur and can sometimes cause many dependent neurological conditions and cutaneous and skeletal disfigurement. Depression and social anxiety may occur as a result of disabilities caused by the condition Neurofibromas may, in 8-13% of cases, transition into cancer, which can be fatal The NF Clinical Program at St. Louis Children's Hospital maintains a comprehensive list of current NF research studies . Musculoskeletal disorder Musculoskeletal abnormalities affecting the skull include sphenoid bone dysplasia, congenital hydrocephalus and associated neurologic impairment. These abnormalities are non-progressive and may be diagnosed in the fetus or at birth. Disorders affecting the spine include: In NF-1, there can be a generalized abnormality of the soft tissues in the fetus, which is referred to as mesodermal dysplasia, resulting in maldevelopment of skeletal structures. Meningoceles and formation of cystic diverticula of the dura of the spine, unrelated to Spina bifida Radiographically, dural ectasia can lead to scalloping of the posterior vertebral bodies and to the formation of cystic diverticula of the dura of the spine. This may result in temporary or permanent loss of lower extremity sensorimotor function. Focal scoliosis and/or kyphosis are the most common skeletal manifestation of NF-1, occurring in 20% of affected patients. 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