Back of an elderly woman with neurofibromatosis
|Classification and external resources|
Neurofibromatosis (NF) refers to several genetically inherited conditions that are clinically and genetically different and carry a high possibility of tumor formation. This disorder is divided into neurofibromatosis type 1, neurofibromatosis type 2 and schwannomatosis.
Signs and symptoms
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:
- Six or more light brown dermatological spots (“café-au-lait spots")
- At least two neurofibromas
- At least two growths on the eye's iris
- Abnormal growth of the spine (scoliosis)
Neurofibromatosis is an autosomal dominant disorder, which means only one copy of the affected gene is needed for the disorder to develop. Therefore, if only one parent has neurofibromatosis, his or her children have a 50% chance of developing the condition as well.The affected child could have mild NF1 even though inherited from a parent with a severe form of the disorder. The types of neurofibromatosis are:
- Neurofibromatosis type I, in which the nerve tissue grows tumors (neurofibromas) that may be benign and may cause serious damage by compressing nerves and other tissues.
- Neurofibromatosis type II, in which bilateral acoustic neuromas (tumors of the vestibulocochlear nerve or cranial nerve 8 (CN VIII) also known as schwannoma) develop, often leading to hearing loss.
- Schwannomatosis, in which painful schwannomas develop on spinal and peripheral nerves.
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). Conditions which may be confused with NF-1 but which are not considered NF include, LEOPARD syndrome, and Legius syndrome The diagnosis of neurofibromatosis is done via the following means:
Surgical removal of tumors is an option, however the risks involved should be assessed first. With regard to OPG (optic pathway gliomas), the preferred treatment is chemotherapy. However, radiotherapy isn't recommended in children who present with this disorder. It is recommended that children diagnosed with NF1 at an early age have an examination each year, which allows any potential growths or changes related to the disorder to be monitored.
In most cases, symptoms of NF1 are mild, and individuals live normal and productive lives. In some cases, however, NF1 can be severely debilitating and may cause cosmetic and psychological issues. The course of NF2 varies greatly among individuals. In some cases of NF2, the damage to nearby vital structures, such as other cranial nerves and the brain stem, can be life-threatening. Most individuals with schwannomatosis have significant pain. In some extreme cases the pain will be severe and disabling.
NF1 occurs in 1 in 3000 individuals and is equally prevalent among men and women. Furthermore, it is among the most common inherited nervous system disorders. Such individuals have a 10 to 15 year reduction in life expectancy compared to the average person.
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