Neurofibromatosis

Neurofibromatosis Austin Higgins Neurofibromatosis is an autosomal dominant genetic disorder. It encompasses a set of distinct genetic disorders that cause tumors to grow along types of nerves and, in addition, can affect the development of non-nervous tissues such as bones and skin. The tumors can grow anywhere on or in the body. This disorder can affect all races, all ethnic groups and each sex with the same probability. Neurofibromatosis has, apart from the most common form, different types. NFM (Neurofibromatosis) type 1, also known as Von Reclkingshausen disease, has an incidence of 1:3000. NFM type II "MISME Syndrome" has an incidence of 1:40,000. Schwannomatosis, is the most unique form. It has different distinct types. This makes about 1/3 of the patients only have one tumor, instead of many. Schwannomatosis has an occurrence of 1:40,000. The tumors that come about from this type are always benign. There are also six other very rare types that are still relevant. Mendelian Inheritance in Man (OMIM) 162210 Mendelian Inheritance in Man (OMIM) 162220 Mendelian Inheritance in Man (OMIM) 162240 Mendelian Inheritance in Man (OMIM) 162260 Mendelian Inheritance in Man (OMIM) 162270 Mendelian Inheritance in Man (OMIM) 601321 Some symptoms of NFM are multiple neurofibromas (Neurofibromas infiltrate the nerve and splay apart the individual nerve fibers). These can be under or on the skin. They can appear anywhere, and usually increase with age. Developing of freckles on the groin area and arm pits, tumors(benign and malignant), pigmented birthmarks, scoliosis, or bowing of the legs, lisch nodules, or a tumor on the optic nerve. The symptoms may vary from type to type, but they sometimes come in the form of hearing loss, headaches, vertigo, facial paralysis, brain tumors, or deafness. With the Schwannomatosis, the gene that this type is involved with has not yet been found. Schwannomatosis generally has noticeable symptoms. These include multiple Schwannomas, tumors, chronic pain, weakness and numbness. Schwannomatosis is unique in the sense that it does not and cannot give the person hearing loss. This is because Schwannomas develop to a single part of the body 1/3 of the time, and they cannot develop on vestibular nerves. People with this disease do not have any mental learning disabilities that come from the disease. The chromosomes at which the NFM types 1 and 2 have been identified on are chromosomes 17, and 22. Therefore, a child of a parent with NFM type 1 or NFM type 2 and an unaffected parent will have a 50% chance of inheriting the disorder. Both NFM type 1 and NFM type 2 are autosomal dominant disorders, which mean that only one copy of the mutated gene need be inherited to pass the genetic disorder. In NFM type 1, there are no links that are easily seen

between genotype and phenotype. However, in NFM type 2, the similarities can be seen. Neurofibromatosis 1 and 2 can both be randomly mutated and appear. Even if there is no family history of it. These random mutations make up half of the Neurofibromatosis cases. However, people who receive the spontaneous generation of Neurofibromatosis cannot pass it on to their children. It is only if one has a family history and carries the gene for the disorder, can he or she pass it on to his or her children. Currently there are no cures for any of the Neurofibromatosis types. Treatments for both NFM1 and NFM2 are presently aimed at controlling symptoms. Surgery can help some NFM1 bone conditions and remove tumors; however, there is a chance that the tumors may grow back and in greater numbers. In the rare instances when tumors become malignant, treatment includes surgery, radiation, or chemotherapy. Surgery to remove tumors is one choice, but side effects may include loss of hearing. Genetic testing is available for families that have a history with Neurofibromatosis. Recently, breakthrough research showed that the NFM1 gene was on chromosome 17. As the NINDS states “Several years ago, research teams located the exact position of the NF1 gene on chromosome 17. The product of the NF1 gene is a large and complex protein called neurofibromin. One portion of this protein is similar to a family of proteins called GAP (guanosine triphosphatase-activating protein). Scientists have demonstrated that GAP proteins play a significant role in tumor suppression in certain cancers. The similarity of the NF1 protein to GAP proteins suggests that the NF1 protein may have a similar switching role in the development of neurofibromas. Scientists theorize that defects in the gene may lessen or inhibit the normal output of its protein and allow the irregular cell growth that may lead to tumor development. Intensive efforts have led to the identification of the NF2 gene on chromosome 22. The NF2 gene product is a tumor suppressor protein. Basic studies in molecular genetics may lead one day to nonsurgical or pharmacologic treatments aimed at retarding or suppressing tumors associated with the neurofibromatoses. The Interinstitute Medical Genetics Research Program at the NIH Clinical Center conducts NF2 family history research. Using specimens from some of the families, scientists have isolated and sequenced the NF2 gene and have described two different patterns of clinical features in NF2 patients. Investigators are continuing to study these patterns to see if they correspond to specific types of gene mutations.”