Four proteins, follistatin, interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta) and kallikrein-5 (KLK5), were found at significantly lower levels in the ALS samples than in control samples (p<0.001) (Table 1 and Fig 3), but IL-1beta was below LOD. Here, KLK5 is linked to amyotrophic lateral sclerosis.