NEFL and proximal spinal muscular atrophy: However, based on findings from Olsson et al. [48], NfL emerges as a superior biomarker to tau for monitoring nusinersen treatment response in SMA patients, particularly for reasons of greater magnitude of change, with NfL showing a substantially larger decrease (4598 ± 981 to <380 pg/mL) compared to tau, and the rate of NfL reduction (−879.5 pg/mL/dose) that was nearly 8-fold greater than tau (−112.6 pg/mL/dose) (Olsson et al. [48]).