Relative differences in mean NfL concentration across groups remained the same for all assays, with lowest–highest mean NfL concentrations observed in healthy controls, multiple sclerosis, dementia with Lewy bodies, Alzheimer’s disease, semantic dementia, corticobasal syndrome, behavioural variant frontotemporal dementia and Huntington’s disease (Supplementary Fig. 2). The gene discussed is NEFL; the disease is semantic dementia.