Neurofibromatosis

Neurofibromatosis (NF) is a group of three conditions in which tumors grow in the nervous system. The three types are neurofibromatosis type I (NF1), neurofibromatosis type II (NF2), and schwannomatosis. In NF1 symptoms include light brown spots on the skin, freckles in the armpit and groin, small bumps within nerves, and scoliosis. In NF2 there may be hearing loss, cataracts at a young age, balance problems, flesh colored skin flaps, and muscle wasting. The tumors are generally non-cancerous. The cause is a genetic mutation in certain genes. These can be inherited from a person's parents, or in about half of cases spontaneously occur during early development. The tumors involve supporting cells in the nervous system rather than the neurons. In NF1 the tumors are neurofibromas (tumors of the peripheral nerves), while in NF2 and schwannomatosis tumors of Schwann cells are more common. Diagnosis is typically based on the signs and symptoms and occasionally supported by genetic testing. There is no known prevention or cure. Surgery may be done to remove tumors that are causing problems or have become cancerous. Radiation and chemotherapy may also be used if cancer occurs. A cochlear implant or auditory brainstem implant may help some who have hearing loss. In the United States, about 1 in 3,500 people have NF1 and 1 in 25,000 have NF2. Males and females are affected equally frequently. In NF1, symptoms are often present at birth and otherwise develop before 10 years of age. While the condition typically worsens with time, most people with NF1 have a normal life expectancy. In NF2, symptoms may not become apparent until early adulthood. NF2 increases the risk of early death. Descriptions of the condition occur as far back as the 1st century. Neurofibromatosis (NF1) in early life may cause learning and behavior problems – about 60% of children who have NF1 have a mild form of difficulty in school. In terms of signs the individual might have are the following: Neurofibromatosis is an autosomal dominant disorder, which means only one copy of the affected gene is needed for the disorder to develop. If one parent has neurofibromatosis, his or her children have a 50% chance of developing the condition as well. The severity of the condition of the parent does not affect the child; the affected child may have mild NF1 even though inherited from a parent with a severe form of the disorder. The types of neurofibromatosis are: The pathophysiology of neurofibromatosis (type 1) consists of the NF1 gene protein. This protein is a tumor suppressor and therefore serves as a signal regulator of cell proliferation and differentiation. A dysfunction of neurofibromin can affect regulation, and cause uncontrolled cell proliferation. Schwann cells in neurofibromas have a mutation in the NF1 alleles. The neurofibromatoses are considered as RASopathies and as members of the neurocutaneous syndromes (phakomatoses).The diagnosis of neurofibromatosis is done via the following means: