NEFL and neuropathy: NfL are also purposed as a biomarker for neuropathies such as the familiar amyloidotic polyneuropathy (Maia et al., 2020; Romano et al., 2024), even if the best neuroanatomical correlation in ALS was demonstrated between upper motor neurodegeneration and the NfL (Gille et al., 2019; Poesen et al., 2017) and lower motorneuron degeneration and the plasmatic NfH (Poesen et al., 2017).