NF1 and neurofibromatosis type 1: As approximately half of the clinically diagnosed NF1 population can be classified at the molecular level as having neurofibromatosis type 1 (i.e. proven presence of a germline mutation in NF1), there are most likely other genomic regions that are also responsible for the disease and it has been hypothesized that mutations in genes other than NF1 may be necessary for the development of the full phenotype.