Further characterization of TDP-43 in yeast identified TDP-43 as having the innate ability to aggregate as pure TDP-43 readily formed inclusions, which were structurally identical to aggregates in degenerating neurons of patients with ALS and frontotemporal lobar degeneration with ubiquitin- and TDP-43-positive inclusions (FTLD-U). This evidence concerns the gene TARDBP and frontotemporal dementia.