Neurofibromatosis Type I
Patient Information
Characteristics
Background and History
Neurofibromatosis is a multisystem progressive disorder characterized primarily by the growth of benign tumors throughout the body. It is often referred to as von Recklinghausen disease since the German pathologist, Friedrich Daniel von Recklinghausen, described it in 1882.
Clinical Correlations
There is considerable variability in the disease manifestations even within families. The growth of small tumors that grow from the coverings of nerves may impact a variety of organs. Among the most serious ones are those that arise from nerves of the visual pathway which often appear in the first decade of life. These may destroy some of the visual fibers and thereby result in loss of vision. Many patients have small pigmented skin lesions called café-au-lait spots. There may also be increased freckling in the armpit and groin areas. Many of these nerve tumors are benign and in severe cases appear over the entire body as small to medium sized bumps.
Blood vessels are often involved and their malformations may lead to renal disease and hypertension. In other cases, blood flow to major organs is compromised and loss of function results. Shortness of stature, abnormal curvature of the spine, and osteoporosis are common. Mental function is usually normal although some patients have learning disabilities. In rare patients malignant tumors of the nerves develop and sometimes other cancers are found.
Genetics
Inheritance
This is an autosomal dominant disorder. However, up to half of patients with this disease have it as a result of a new mutation and the characteristic vertical pattern of transmission is missing. Parents who have neurofibromatosis can expect that half of their children will also inherit the mutation.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
The diagnosis is often made by pediatricians or ophthalmologists when patients present with symptoms of visual or growth problems. Some children may present with symptoms of high blood pressure as well. No treatment is available for the primary disease but major blood vessel disease, hypertension, and scoliosis may require treatment. Some tumors of the vision pathways require surgery but they are often slow growing and sometimes even regress so that conservative observation is often the most prudent course. Nevertheless, because of the lifelong risk of complications and the progressive nature of this disorder, health monitoring is necessary throughout life.
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