NEFL and amyotrophic lateral sclerosis: There may be multiple NfL species as axons degrade as suggested by a recent study using immunocapture coupled with mass spectrometry where multiple molecular weight species of NfL were identified in Alzheimer’s CSF, but no full-length NfL was detected.107 Intriguingly, Malaspina et al. 45 also found the main NfL band in plasma samples from ALS patients on a western blot was 22 kDa (not 61 kDa).