Table 1.

Comparison of Neurofibromatosis Type 1 and Proteus Syndrome

Neurofibromatosis Type 1Proteus Syndrome
PrevalenceFrequent (1 in 3000 to 1 in 4000 live births worldwide)Extremely rare (<1 in 1,000,000 live births worldwide)
Equally prevalent in men and womenTwo men for every woman
GeneNF1, chromosome 17Unknown
Transmission50% hereditary (autosomal dominant)Sporadic
50% sporadic (de novo mutation)Postzygotic somatic mutation (embryonic lethal in nonmosaic form)
Diagnostic criteria
    GeneralCafé-au-lait spotsMosaic distribution of lesions
NeurofibromasSporadic occurrence
Axillary or inguinal frecklingProgressive course
Optic gliomas
Lisch nodules
Characteristic osseous lesion (sphenoid dysplasia, thinning of long bone cortex with or without pseudoarthrosis)
First-degree relative with neurofibromatosis type 1
    OtherCerebriform connective tissue nevus
Linear epidermal nevus
Asymmetric, disproportionate overgrowth
Specific tumors before second decade
Lipomas or focal atrophy of adipose tissue
Capillary, venous, or lymphatic malformation
Facial features including dolichocephaly, a long face, down-slanting palpebrae, ptosis, depressed nasal bridge, anteverted nares, and open-mouth position while at rest