There are two genetically distinct forms of neurofibromatosis. Genes are a chemical alphabet stored in the body. Genes contain the body’s ‘built-in’ plan to make sure all the parts of the body work correctly. If a gene has a misprint in the chemical alphabet then a part of the body may not work correctly. A child with neurofibromatosis has often been passed (inherited) a
gene with a misprint in it from one parent. The gene causes neurofibromatosis. This is called autosomal dominant inheritance. Sometimes, by chance, a new misprint occurs in the gene that causes neurofibromatosis. Both this child’s parents will have normal genes with no misprints. NF1 and NF2 are both autosomal dominant genetic conditions. They are however caused by two different genes developing misprints.
The gene for NF-1 is more commonly affected and is located on chromosone 17. It is known as "peripheral neurofibromatosis." The gene for NF-2 is less commonly affected and is located on chromosone 22. It is called "central neurofibromatosis" because it tends to affect parts of the body not readily seen by the outside observer. The rest of this guide will refer specifically to neurofibromatosis type I. NF-1 is due to a defect on chromosome 17; NF-2 results from a defect on chromosome 22. Both of these disorders are inherited in a dominant fashion. This means that anybody who receives just one defective gene will have the disease. However, a family pattern of NF is only evident for about half of all cases of NF. The other cases of NF occur due to a spontaneous mutation (a permanent change in the structure of a specific gene). Once such a spontaneous mutation has been established in an individual, however, it is then possible to be passed on to any offspring. The chance of a person with NF passing on the NF gene to a child is 50%.
All information is intended for reference only. Please consult your physician for accurate medical advices and treatment. Copyright 2005, health-cares.net, all rights reserved. Last update: July 18, 2005