Here we report the detailed description of a child with a <i>de novo</i> gain of function (GoF) mutation in the gene Ca/Calmodulin dependent protein kinase 2 beta (<i>CAMK2B</i> c.328G > A p.Glu110Lys) who presents with developmental delay and periodic neuropsychiatric episodes. This evidence concerns the gene CAMK2B and Global developmental delay.