Neurological disorders are often thought to be irreversible, but there have been several reports that some phenotypes can be reversed in mouse models, including Rett syndrome (20), Kabuki syndrome (21), Rubinstein–Taybi syndrome (22), SYNGAP1 deficiency (23), and autism spectrum disorders due to SHANK3 mutations (24). This evidence concerns the gene SYNGAP1 and hyperinsulinemic hypoglycemia, familial, 4.