In our study, the diagnostic yield of WES was 27% (14/52) in patients with neurodevelopmental disorders [CRTR deficiency (n = 1); ARX disease (n = 1); KDM5C disease (n = 1); GABRB3 disease (n = 1); KIAA2022 disease (n = 1); KCNA2 disease (n = 1); PMM2-CDG (n = 2); SYNGAP1 disease (n = 1); Angelman syndrome (n = 1); PURA disease (n = 1); EARS disease (n = 1); HECW2 disease (n = 1); KAT6B disease (n = 1)]. This evidence concerns the gene KCNA2 and hyperinsulinemic hypoglycemia, familial, 4.