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In medicine, the neurofibromatoses (singular, neurofibromatosis) are certain genetic disorders of the nervous system.
Neurofibromatoses primarily affect the development and growth of neural (nerve) cell tissues. These disorders cause tumors to grow on nerves and produce other abnormalities such as skin changes and bone deformities. Although many affected persons inherit the disorder, between 30 and 50 percent of new cases arise spontaneously through mutation (change) in an individual's genes. Once this change has taken place, the mutant gene can be passed on to offspring.
Scientists have classified the disorders as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). NF1 is the more common type of neurofibromatosis. In diagnosing NF1, a physician looks for changes in skin appearance, tumors, or bone abnormalities, and/or a parent, sibling, or child with NF1. Symptoms of NF1, particularly those on the skin, are often evident at birth or during infancy and almost always by the time a child is about 10 years old.
NF2 is less common. NF2 is characterized by tumors occurring bilaterally (on both sides of the body) on the eighth cranial nerve. The tumors damage neighboring nerves by placing them under pressure. To determine whether an individual has NF2, a physician looks for bilateral eighth-nerve tumors and similar signs and symptoms in a parent, sibling, or child. Affected individuals may notice hearing loss as early as the teen years. Other early symptoms may include tinnitus (a ringing noise in the ear) and poor balance. Headache, facial pain, or facial numbness, caused by pressure from the tumors, may also occur. NF2 is a autosomal dominant disorder located on chromosome 22.
Treatments for both NF1 and NF2 are presently aimed at controlling symptoms. Surgery can help some NF1 bone malformations and can remove painful or disfiguring tumors; however, there is a chance that the tumors may grow back and in greater numbers. In the rare instances when tumors become malignant (3 to 5 percent of all cases), treatment may include surgery, radiation treatment, or chemotherapy. For NF2, improved diagnostic technologies, such as magnetic resonance imaging (MRI), can reveal tumors as small as a few millimeters in diameter, thus allowing early treatment. Surgery to remove tumors completely is one option, but this may result in hearing loss. Other options include partial removal of tumors, radiation, and (if the tumors are not progressing rapidly) the conservative approach of watchful waiting. Genetic testing is available for families with documented cases of NF1 and NF2. However, new (spontaneous) mutations cannot be confirmed genetically. Prenatal diagnosis of familial NF1 or NF2 is also possible utilizing amniocentesis or chorionic villus sampling procedures.
In most cases, symptoms of NF1 are mild, and patients live normal and productive lives. In some cases, however, NF1 can be severely debilitating. In some cases of NF2, the damage to nearby vital structures, such as other cranial nerves and the brainstem, can be life-threatening.
The most famous victim of this disease may have been Joseph Merrick, the Elephant Man. In the 1970s, it was widely believed that Merrick suffered from NF1. However, recent opinion has shifted to the belief that Merrick actually suffered from the rare condition Proteus syndrome. Recent examination of his remains, including DNA tests, led Charis Eng to conclude that Merrick had Proteus syndrome but may have had NF1 in addition.
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