Although plasma NfL is not a specific AD biomarker, it has been positively associated with higher risk of cognitive decline in cognitively normal older adults, MCI and AD patients (Mattsson et al., 2017; Aschenbrenner et al., 2020; Lee et al., 2022) and higher CSF NfL concentration in the early presymptomatic stages of familial AD (Preische et al., 2019) and in all stages of sporadic AD (Mattsson et al., 2017). The gene discussed is NEFL; the disease is Alzheimer disease.