SYNGAP1 and cardiofaciocutaneous syndrome: While patients with cardio-facio-cutaneous syndrome (CFC), Costello syndrome (CS) and SYNGAP1-related encephalopathy show moderate to severe intellectual disabilities and neurodevelopmental delay, epilepsy and autism spectrum disorder (Roberts et al., 2006; Armour and Allanson, 2008; Schulz et al., 2008; Adviento et al., 2014; Pierpont et al., 2022), patients with Noonan syndrome (NS) and neurofibromatosis type 1 are generally less severely affected.