TDP-43 in amyotrophic lateral sclerosis - is it a prion disease?

Amyotrophic lateral sclerosis is a devastating disease characterized by rapidly progressive paresis. The neuropathological hallmark of most amyotrophic lateral sclerosis cases are neuronal and glial aggregates of phosphorylated 43-kDa TAR DNA-binding protein (pTDP-43). The accumulation of similar proteins into insoluble aggregates is now recognized as a common pathological hallmark of neurodegenerative diseases in general. Importantly, many of these proteins such as tau and amyloid-β in Alzheimer's disease and α-synuclein in Parkinson's show a stereotypical sequential distribution pattern with progressing disease. In this review, we discuss recent evidence that TDP-43 in ALS may propagate similarly to other neurodegenerative disease proteins. We furthermore delineate similarities and important differences of TDP-43 proteinopathies to prion diseases.