Dominant mutations in the GNAO1 gene (RefSeq NG_042800.1, NM_020988.3) underlie a complex constellation of infantile/childhood-onset severe neurological disorders characterized by global developmental delay (GDD), intellectual disability (ID), hypotonia, movement disorders (MD), drug-resistant seizures and neurological deterioration (1,2). This evidence concerns the gene GNAO1 and Global developmental delay.