0521779407-15 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:43
Neurofibromatosis 1045■CALMs tend to be large, pale, few in number.
NF-1 NEVER progresses to NF-2; they are separate diseases.
Other types of NF (3–8) now thought to be mosaics of NF-1tests
■NF is a clinical diagnosis.
Skin biopsy of CALM is nonspecific.
■Skin biopsy for neurofibroma
■Slit-lamp exam for Lisch nodules
■Other tests depending on organ affected
■Genetic counseling strongly suggested
■Causative Gene:
■NF-1
➣17q11.2
➣ras-GAP protein
A tumor suppressor gene
Gene product: neurofibromin
■NF-2
➣22q11
■Prenatal Testing
➣Only if DNA data from family members known
■Genetics
➣Autosomal Dominant
➣30–50% cases are spontaneous mutations
➣Postzygotic mutation is the probable cause of segmental NF
■Statistics
➣NF-1 occurs in 1 in 3,500
➣NF-1 represents 96–97% of all NF cases
➣NF-2 occurs in 3%
NB: No consistent prenatal complications
Check parents of NF-1 child; they may be mosaics.
If parent is a mosaic, chance of second child with full NF-1 <3%.differential diagnosis
■CALM
➣Single CALMs do occur frequently in Caucasians, more occur in
dark-skinned races.
➣Multiple CALMs are strongly suggestive of NF-1, but not a sine
qua non.
➣Solitary large segmental CALMs exist frequently unrelated to any
syndromes.