Some studies have shown that the imbalance of cytokine profiles was also reflected in the CSF of neurodegenerative patients, for example the observation of an increase of proinflammatory cytokines (IL-6, IL-1β) in PD patients (Chen et al., 2018), as well as increased inflammatory mediators (PGLYRP2, APOA4), metalloproteinases (MMP-3 and MMP-9), clustering and complement factors in the CSF of HD patients (Rocha et al., 2016; Table 1). The gene discussed is MMP9; the disease is Huntington disease.