NF1 and neoplasm: Although somatic inactivation of the NF1 wild-type allele is considered to be the PNF-initiating event in NF1 patients with intragenic mutations and patients with NF1 microdeletions [40], both patient groups may differ with regard to tumour progression because of the heterozygous constitutional deletion of SUZ12 present only in patients with NF1 microdeletions.