MAPT and amyotrophic lateral sclerosis: Overall, these studies have identified increased levels of TDP‐43 in CSF from ALS patients compared with controls.3 An elevated level of TDP‐43 has also been reported in plasma from ALS patients in one case–control study.4 However, the absolute concentrations of TDP‐43 in CSF and plasma have varied across studies, suggesting that TDP‐43 immunoassays are inconsistent for measuring this protein within biofluids.3 The other candidate is Tau.