However, the p-values were reduced for the ALS vs. mimic disease control subgroup comparison (Table 3, first row) relative to the ALS vs. all disease control subgroup comparison (Table 2, “ALS vs. DC”) suggesting a stronger trend toward statistical significance when cystatin C is used to differentiate ALS patients from this more clinically-relevant control group. Here, CST3 is linked to amyotrophic lateral sclerosis.