Regarding ALS patients, IL-21 was lower in patients with a fast progression compared to slow or medium progressors (6.3 ± 3.83 pg/mL vs. 25.1 ± 20.7 vs. 25.3 ± 13.48, p = 0.029) (Figure 1). This evidence concerns the gene IL21 and amyotrophic lateral sclerosis.