However, we previously evaluated plasma neurofilament light (NfL) protein, a marker of neuronal injury, across FTD spectrum disorders and in presymptomatic FTD mutation carriers; we found that NfL was elevated in presymptomatic mutation carriers prior to phenoconversion and in participants with FTD, and it associated with indicators of disease severity [5]. This evidence concerns the gene NEFL and frontotemporal dementia.