MAPT and proximal spinal muscular atrophy: The linear regression model, adjusted for age and sex, revealed significantly increased levels of total tau in CSF samples from non-treated SMA patients (SMA(Pre): 181.29 ± 12.98 pg/mL) compared to CSF samples from healthy controls (control: 176.21 ± 15.55 pg/mL) due to the group effect [F(1,58) = 11.366, p = 0.0012].