The well‐established role of MMP‐9 in regulating NMDA signaling, dendritic spine morphology, and prefrontal and hippocampal function (Huntley, 2012; Vafadari et al, 2016) has drawn attention to the potential involvement of MMP‐9 in the development of schizophrenia (Lepeta & Kaczmarek, 2015). This evidence concerns the gene MMP9 and schizophrenia.