Neurofibromatosis: past, present, and future
Article Abstract:
Neurofibromatosis (NF) type 1, also called von Recklinghausen neurofibromatosis, is a dominant genetic disorder. Much research has been done on the gene for this syndrome; the gene has been identified as an enormous stretch of DNA on chromosome 17, between 200 and 300 kilobases of DNA in length. The gene seems to code for a protein with guanosine diphosphatase-activating activity, which suggests that it plays an important role interacting with other famous genes, such as the oncogene ras, in the regulation of cell replication. Despite the depth of knowledge about the type 1 NF gene, the diagnosis of the disorder is not straightforward. Until new genetic tools become available, the diagnosis must still be made on the basis of physical examination. The gene is so large that new mutations are common, so not all affected individuals have a family history of the disease. The expression of the characteristic neurofibroma tumors underlying the skin may not take place until the patient is an adolescent or an adult. Another characteristic feature of NF, cafe au lait spots on the skin, is not very specific. A third feature of the disease is the presence of Lisch nodules. These benign growths on the iris (the colored portion of the eye) are easy to see using a slit-lamp (which is commonly used in visual examinations). Often, the nodules can be seen by conventional examination. In the May 2, 1991 issue of The New England Journal of Medicine, researchers demonstrate that the Lisch nodule is a reliable sign for the diagnosis of neurofibromatosis type 1. In this study, the nodules were common among the children with NF type 1, and all NF patients over 21 years had them. It seems reasonable to imagine that the children who do not have nodules will develop them at some point. Patients with NF type 1 are at high risk for the development of gliomas (tumors) on the optic pathway; about 15 percent of NF patients will develop such a glioma and a third of these will be at risk for visual dysfunction. While the gliomas associated with NF type 1 can not be prevented, the diagnosis of patients with neurofibromatosis coupled with the screening for early detection of the gliomas can minimize the impact of these tumors on the patient. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: The New England Journal of Medicine
Subject: Health
ISSN: 0028-4793
Year: 1991
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Lisch nodules in neurofibromatosis type 1
Article Abstract:
Neurofibromatosis (NF) type 1, also called von Recklinghausen's neurofibromatosis, is a common genetic disorder. The genetic trait is inherited as a Mendelian dominant trait (inheriting the gene from one or both parents generally results in the disease). However, mutations in the gene for NF are so common that half of all cases may represent new mutations rather than inherited mutations. The diagnosis of neurofibromatosis is not always easy in children. Sometimes affected children will have no symptom other than cafe au lait spots (coffee-with-milk colored skin blemishes) which, by themselves, are not specific enough to form the basis of a diagnosis. A highly diagnostic feature of many cases of type 1 NF is the Lisch nodule. These nodules are melanocytic hamartomas of the iris (the colored area of the eye). That is, they are benign growths composed of cells that appear to be examples of normal cells of the tissue from which they arise. However, it is not necessary to use a microscope to evaluate the Lisch nodule. These conveniently located diagnostic signs may be easily seen in the iris on visual examination, though they are more readily observed using a slit lamp. A study was undertaken to evaluate the effectiveness of using Lisch nodules in the diagnosis of type 1 NF. A total of 167 patients were evaluated: 162 from families with a history of neurofibromatosis and 5 children with suspected NF. Overall, Lisch nodules were observed in 123 patients. Lisch nodules, however, were more common among the older patients. In three- and four-years-old children, only 44 percent had the nodules. Between the ages of five and six years, about 55 percent had the tiny growths. All 65 patients in the present study who were over 21 years had Lisch nodules. The study indicates that Lisch nodules are more likely to be present in young patients than are actual neurofibromas. Looking for Lisch nodules, then, is a simple noninvasive method for determining a diagnosis of neurofibromatosis type 1 in young patients with otherwise ambiguous signs. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: The New England Journal of Medicine
Subject: Health
ISSN: 0028-4793
Year: 1991
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Homozygous inactivation of the NF1 gene in bone marrow cells from children with neurofibromatosis type 1 and malignant myeloid disorders
Article Abstract:
Some children with neurofibromatosis type 1 and diseases of the bone marrow have a mutation in the neurofibromatosis type 1 (NF1) gene. Neurofibromatosis increases the risk of benign and malignant tumors, including leukemia. Researchers used DNA sequencing to detect mutations of the NF1 gene in bone marrow samples from 18 children with neurofibromatosis type 1 and some type of bone marrow disorder. Eight of the children had a mutation and five of these children were missing both functional copies of the gene. The NF1 gene is thought to be a tumor suppressor gene.
Publication Name: The New England Journal of Medicine
Subject: Health
ISSN: 0028-4793
Year: 1997
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