The estimated lifetime risk of an MPNSTin all NF1 patients is 8–13% (Evans et al. 2002, 2012) or 15.8%according to Uusitalo et al. (2016).However, individuals with NF1 microdeletionshave an even higher lifetime MPNST risk, in the range of 16–26% (De Raedt et al.2003; Mautner et al. 2010). This evidence concerns the gene NF1 and malignant peripheral nerve sheath tumor.