Niebroj-Dobosz et al. reported that in mild cases of ALS, expressions of MT-MMP-1, MMP-2, MMP-9, and TIMP-1 are elevated in serum compared to CSF, where MT-MMP-1, MMP-2, and TIMP-1 were upregulated or unchanged while MMP-9 levels were decreased [75]. Here, MMP9 is linked to amyotrophic lateral sclerosis.