Neurofibromatosis

Neurofibromatosis is one of the most common genetic diseases affecting the nervous system.  The incidence is approximately 1 in 3000 live births.

Four forms are described in the literature:

1. Neurofibromatosis type 1 (aka NF1, von Reckinghausen disease, Classic neurofibromatosis, peripheral neurofibromatosis)
   
2. Neurofibromatosis type 2 (aka NF2, central neurofibromatosis, familial acoustic neuromas)
3. Neurofibromatosis type 3 (aka NF3A, mixed central and peripheral neurofibromatosis, Riccardi neurofibromatosis)
   
4. Neurofibromatosis type 4 (aka NF4, variant forms of neurofibromatosis, atypical neurofibromatosis)

NF1 is the most common form of neurofibromatosis.  It has an incidence of approximately 1 in 3000 live births.  It has autosomal dominant inheritance, with the abnormal gene located on chromosome 17.  About 50% of cases are due to spontaneous mutation, with no prior family history.

Diagnostic Criteria 

Two or more of the following should be present:

• 6 or more cafe au lait spots, each >5mm in diameter before puberty, or >15mm in diameter after puberty
• 2 or more neurofibromas -or- one plexiform neurofibroma
• Axillary or groin freckling
• Optic pathway glioma
• 2 or more Lisch nodules
• Osseous lesions such as sphenoid dysplasia or long bone thinning
• First-degree relative with NF1