In support of the latter hypothesis, the mutational landscape of cNF across 40 tumors from 11 patients revealed that the nature of the second hit mutation in NF1 is different in each tumor.45 It is currently unknown if there are different forms of cNF or if there are relatively few types of cNF that appear phenotypically distinct because they are observed at various stages along a growth continuum.31,46 A challenge is that cNF may not be visible at early stages and some patients report that cNF erupt over very short intervals. This evidence concerns the gene NF1 and neoplasm.