 The MMP-9-RS20544C-T single nucleotide polymorphism, SNP, located in the 3-foot untranslated region, UTR, was associated with increased severity of a chronic delusional syndrome in schizophrenia patients. This SNP affects the expression of MMP-9, leading to changes in dendritic spine morphology and altered binding of fragile X-mental retardation protein, FMRP. These changes are thought to be responsible for the increased risk of psychotic symptoms seen in individuals carrying this SNP. This article was authored by Cartazena Lepita, Cartazena J. Perzica, Cartazena Pacholska Wixorek, and others.