Plasma GFAP significantly differed among A+T+, A+T−, A−ALS patients and controls (p < 0.0001), with each A+ ALS subgroup showing higher values than controls (A+T+ vs. controls, p < 0.0001; A+T− vs. controls, p = 0.0003) and A− subjects (A+T+ vs. A−, p < 0.0001; A+T− vs. A−, p = 0.02). The gene discussed is GFAP; the disease is amyotrophic lateral sclerosis.