This new concept is supported by our investigation encompassing the assessment of plasma sEV indices in a relatively large group of FTLD patients, including sporadic patients, genetic patients (intermediate/pathological C9orf72 expansion carriers, GRN heterozygous mutation carriers), and GRN homozygous mutation carriers affected by NCL, a lysosomal storage disorder. The gene discussed is GRN; the disease is lysosomal storage disease.