We then determined the levels of MMP-2 and MMP-9 in a separate validation set of thirty serum samples from ALS (Group 3, Table 1: 19 males, 11 females; mean age ± SD, 60.9 ± 7.9 years), with a matched set of CSF samples (Group 4, Table 1) from the same ALS, and compared their levels with a separate set of twenty serum samples from age-matched HC (Group 5, Table 1: 12 males, 8 females; 60.6 ± 5.5 years of age) and fourteen CSF samples from a group of age-matched individuals with other neurological diseases (Group 6, Table 1, OND: 8 males, 6 females; 63.6 ± 9.8 years of age). Here, MMP9 is linked to amyotrophic lateral sclerosis.