Although those results cannot be considered exclusive of migraine, but rather related to the CSD phenomenon (that also participates in the migraine mechanisms), elevated plasma levels of MMP-9 have been reported in migraine patients (Leira et al., 2007; Imamura et al., 2008; Martins-Oliveira et al., 2012) and MMPs, especially MMP-2 and MMP-9, have been linked to BBB disruption, as well as augmented influx of inflammatory cells into the CNS (Rosenberg et al., 2001; Gurney et al., 2006; Yang et al., 2007; Bernecker et al., 2011). The gene discussed is MMP9; the disease is migraine disorder.