Thus, the presenting signs and symptoms may vary widely. These descriptions are not especially accurate, as NF-1 often has central features. Segmental NF may be related to mosaicism or segmental hyperexpression of the condition. Loss of heterozygosity may create the clinical impression of segmental lesions. The carrier incidence at birth is 0.0004, and the gene frequency is 0.0002.
Signs can range from benign cutaneous manifestations to profound disfigurement.
The mortality rate is higher than that of the normal population, due to increased potential for malignant transformation of diseased tissues and the development of neurofibrosarcoma. All ethnic groups are affected equally. Although most individuals who develop neurofibromatosis are not born with caf au lait macules, these skin lesions develop during the first 3 years of life, prompting parents to bring a child to medical attention. Neurofibromas form in late adolescence. Caf au lait spots are irregularly shaped, evenly pigmented, brown macules.