NF1 and optic pathway glioma: Other NF1-associated features such as Lisch nodules, neurofibromas, NF1-specific bone lesions, optic pathway gliomas, and malignant peripheral nerve sheath tumours are however absent in patients with Legius syndrome (Brems et al. 2007, 2012; Messiaen et al. 2009; Pasmant et al. 2009; Spurlock et al. 2009; Laycock-van Spyk et al. 2011; Brems and Legius 2013; Denayer and Legius 2020).