GFAP and proximal spinal muscular atrophy: The systematic review by Gavriilaki et al. [47] of real-world observational studies suggests that several biomarkers, including serum creatinine, creatine kinase activity, as well as cerebrospinal fluid (CSF) Aβ42, glial fibrillary acidic protein (GFAP) concentrations, ulnar compound muscle action potential (CMAP), and single motor unit potential (SMUP) amplitude, may help predict the therapeutic response in patients with SMA types 2, 3, and 4 who are over the age of 11 and undergoing treatment with nusinersen.