Neurofibromatosis Type II
Patient Information
Characteristics
Background and History
Neurofibromatosis is a multisystem progressive disorder characterized primarily by the growth of benign neural tumors throughout the body. It consists of two types, I and II, with distinct clinical and genetic features.
Clinical Correlations
Type II has more significant eye involvement than type I. Cataracts, retinal tumors and a membrane overlying the retina are common and are often found in children. Tumors of the optic nerve can cause serious damage and can lead to blindness. Similar tumors, called meningiomas, are often found in the brain as well. Other growths attached to nerves, known as schwannomas, are found throughout the body and often appear as skin bumps which may be painful. The disease often presents in the third and fourth decades as hearing loss associated with ringing in the ears that is caused by tumors growing on the auditory nerve. These may also cause problems with balance. Hearing problems are often bilateral and may occur in children also.
Genetics
Inheritance
This is an autosomal dominant disorder with a vertical pattern of transmission. However, up to half of cases arise from new mutations and have no family history of the disease.
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 of neurofibromatosis II should be suspected in any young person with the onset of hearing loss and ringing in one or both ears. An MRI of the brain and a detailed systemic examination should be performed to look for other growth. Small lesions can sometimes be excised but the growth of these nerve tumors eventually makes removal difficult. The morbidity and symptoms in this disease is dependent largely on the location of the growths and no two patients follow the same course. Most patients live about 15 years following the diagnosis.
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