TARDBP and amyotrophic lateral sclerosis: Authors recognized that TDP-43 as a single biochemical parameter was not able to accurately distinguish ALS patients from controls, and several combinations of PBMC levels of insoluble TDP-43 along with other proteins were proposed, such as soluble peptidyl-prolyl cis–trans isomerase A (PPIA) and hnRNPA2B1 [49].