TDP-43 proteinopathies include sporadic frontotemporal lobar degeneration with tau-negative and ubiquitin-positive inclusions (FTLD-U) with and without motor neuron disease (MND), familial forms of FTLD-U with mutations in the progranulin gene (GRN), valosin-containing protein (VCP), and linkage to chromosome 9p, as well as most forms of amyotrophic lateral sclerosis (ALS) except for familial ALS with Cu/Zn superoxide dismutase 1 (SOD-1) mutations. Here, GRN is linked to amyotrophic lateral sclerosis.