Pathophysiology
Neurofibromatosis type 1 (NF1) is caused by a change in the NF1 gene, which is found on chromosome 17. Some people have features of NF1 that are limited to only one part of their body. This is called mosaic NF1 (also called segmental NF1). Mosaic NF1 is caused by changes in the NF1 gene, but genetic testing for people with this form of NF1 can be more complicated than for people who do not have a mosaic form of NF1.
Neurofibromatosis type 2 (NF2) is caused by a change in the NF2 gene (also called Merlin), which is found on chromosome 22. Some people have features of NF2 that are limited to only one part of their body. This is called mosaic NF2. Mosaic NF2 is caused by changes in the NF2 gene, but genetic testing for people with this form of NF2 can be more complicated than for people who do not have a mosaic form of NF2.