Research comparing exome sequencing data from seven distinct cNF tumours to blood and skin samples obtained from a single patient did not identify somatic mutations in 5/7 cNFs, beyond a second-hit somatic NF1 mutation.52 The other two contained variants in HMCN1 and CEP131 (AZI1), respectively.52 A more recent study of exome data from three growing and three stable cNFs supports the hypothesis that these tumours are genomically quiet.64 Each tumour contained 1–11 somatic mutations, but no correlation was found between the type of variants and growth. Here, NF1 is linked to neoplasm.