Taken together with our finding that the association between sNfL and eGFR depends on age (which indicates that the impact of renal impairment on sNfL levels is even more pronounced in older than in younger patients), these data stress the importance of accounting for renal function when evaluating blood NfL concentrations in elderly populations, in whom chronic kidney disease is highly prevalent (Coresh et al., 2003). This evidence concerns the gene NEFL and chronic kidney disease.