GAD1 and schizophrenia: In line with the evidence, several pathways and the dysfunction of associated genes were suggested to be the primary cause of schizophrenia, such as that of GAD1 (glutamic acid decarboxylase 1, producing GABA from glutamate) [45], N-methyl-D-aspartate (NMDA) receptor (a glutamate receptor and ion channel protein) and both GABA A [46] and GABA B [9, 43] receptors.