Clinically, the majority of patients (N=70, 75.3%) had a diagnosis of NS; 10 (10.7%) subjects were diagnosed with NS/LAH, while 5, 4, and single patients had a diagnosis of cardio-facio-cutaneous syndrome (CFCS; MIM: PS115150) (5.4%), NSML (4.3%), Costello syndrome (MIM: 218040, Legius Syndrome (MIM: 611431), MAPK1-related syndrome (MIM: 619087) and CBL-related syndrome (MIM: 613563) (1.1%), respectively (Table 1). Here, MAPK1 is linked to Costello syndrome.