Our study not only reveals the cellular and even molecular basis of the dynamic changes that occur in patients prior to symptom onset and as the disease progresses, it also suggests a potential utility for Fibronectin1 (FN1) as a potential pharmacokinetic biomarker, especially for ALS patients with SOD1D90A mutation and ALS patients with prominent UMN loss. The gene discussed is FN1; the disease is amyotrophic lateral sclerosis.