Examination of post-mortem ALS and FTLD-TDP brain tissue reveals the presence of low molecular weight TDP-43 species in addition to the full-length protein in detergent-insoluble protein fractions, which contain aggregated proteins, regardless of whether the person had ALS or FTLD (Neumann et al., 2006; Igaz et al., 2008). This evidence concerns the gene TARDBP and amyotrophic lateral sclerosis.