manifested as single or multiple firm, rubbery bumps of varying sizes on a person's skin. Age of onset is puberty. Progressive in number and size. Not malignant. Can be treated with CO2 lasers or by removal by a plastic surgeon specialized in NF1. Eye disease Lisch nodules in the iris. Optic nerve gliomas along one or both optic nerves or the optic chiasm can cause bulging of the eyes, involuntary eye movement, squinting, and / or vision loss. Treatment may include surgery, radiation +/- steroids, or chemotherapy (in children). Neurobehavioral developmental disorder The most common complication in patients with NF-1 is cognitive and learning disability. These cognitive problems have been shown to be present in approximately 90% of children and adults with NF-1 and have significant effects on their schooling and everyday life. These cognitive problems have been shown to be stable into adulthood mainly in the mid 20s to early 30s and do not get worse unlike some of the other physical symptoms of NF-1. The most common cognitive problems are with perception, executive functioning and attention. Disorders include: Approximately 42% of children with NF-1 have symptoms of autism, with 36.78% of them being severe cases, 33.33% being mild to moderate cases, and 29.89% of them having both symptoms of autism and ADHD. Attention deficit hyperactivity disorder has been shown to be present in approximately 40% of children with NF-1. Speech and language delays have also been identified in approximately 68% of preschool children with NF-1. Motor deficits are common. Motor deficits due to NF-1 are probably not cerebellar. Spatial deficit. Lovastatin, normally used to treat hypercholesterolemia, is currently in phase one of clinical trial (NCT00352599). This drug has been shown to reverse spatial deficits in mice. Simvastatin, a drug similar to lovastatin, did not show benefit on cognitive function or behaviour in two randomized controlled trials in children with NF-1. Nervous system disease The primary neurologic involvement in NF-1 is of the peripheral nervous system, and secondarily of the central nervous system. Schwannomatosis is a rare condition defined by the presence of multiple benign tumors of nerves that are frequently very painful. In addition to pain, weakness is a common problem. Symptoms usually begin in young or mid-adult years. Peripheral neuropathy Neurofibroma A neurofibroma is a lesion of the peripheral nervous system. Its cellular lineage is uncertain, and may derive from Schwann cells, other perineural cell lines, or