MMP9 and schizophrenia: A study in the Chinese population (performed on 298 patients with schizophrenia and 298 controls) showed that the T allele of the MMP-9-1562C/T polymorphism of the MMP-9 gene may predispose an occurrence to SZ, and this risk is 1.6 times higher (C allele vs. T allele: odds ratio = 1.564, 95% CI: 1.005∼2.436, p = 0.046) (Han et al., 2011).