The biochemical phenotype is important for predicting the underlying germ-line mutation, for example, SDH and von-Hippel Lindau (VHL) mutations have tumours that usually produce norepinephrine, whereas multiple endocrine neoplasia type 2 (MEN2) and neurofibromatosis type 1 (NF1) are more likely to be associated with tumours producing epinephrine. This evidence concerns the gene NF1 and neoplasm.