This study also identified a correlation between NF1 mutations and a biochemical phenotype: paragangliomas and phaeochromocytomas harbouring a somatic NF1 mutation were found to display higher plasma levels of normetanephrine (P = 0.005) and metanephrine (P = 0.0025), markers for catecholamine-secreting tumours [121]. This evidence concerns the gene NF1 and pheochromocytoma.