Serum NfL levels also directly correlated with Fazekas score (p = 0.012, ρ = 0.562, Table 3-Supplementary material), whereas they did not correlate with MIRS, n(CTG), DM1 clinical form, age at onset, disease duration, NIV treatment, or %forced vital capacity (FVC). Here, NEFL is linked to myotonic dystrophy type 1.