Pathology and genetics of frontotemporal lobar degeneration: an update.

Frontotemporal lobar degeneration (FTLD) is a common form of dementia that usually afflicts patients in their mid-life. Clinically, patients with FTLD present with changes in behavior and/or language dysfunction. According to their underlying neuropathological substrate, these neurodegenerative conditions can now be classified into two main groups: those with tau pathology (tauopathies), and those without tau pathology. In the majority of nontauopathy disorders the recently identified TAR DNA-binding protein-43 (TDP-43) is found as the major inclusion protein (TDP-43 proteinopathies), and TDP-43 is also present in motor neuron inclusions of amyotrophic lateral sclerosis. Presently, mutations in 4 genes (MAPT, PGRN, VCP, CHMP2B) are known to cause diverse types of FTLD pathology. Here, we summarize the recent neuropathological and genetic advances in FTLD research.