MMP-9 especially is believed to play a major role in BBB disruption during ischemic stroke because ischemic stress induces MMP-9 and the plasma MMP-9 concentration, which strongly correlate with patients’ stroke severity (Horstmann et al., 2003; Jin et al., 2010; Reuter et al., 2013). The gene discussed is MMP9; the disease is ischemic stroke.