NF1 and Noonan syndrome: These children may not be affected by NF1 but instead by Legius syndrome or less frequently by another RASopathy such as Noonan syndrome with multiple lentigines (formerly known as LEOPARD syndrome, MIM#151100) or Constitutive mismatch repair deficiency (CMMRD) (Brems et al. 2007; Shah et al. 2010; Santoro et al. 2014; Santos et al. 2016; Wimmer et al. 2017; Suerink et al. 2019; Anderson 2020; Jha et al. 2020; Perez-Valencia et al. 2020).