MAPT and Schnyder corneal dystrophy: In addition, it suggests that plasma p181 tau – with treatment-responsivity now increasingly demonstrated [4, 38]- might also serve a as a potential therapy response biomarker for future treatment trials already targeting the SCD stage charged with clinical meaningfulness – as highly requested for biomarkers by the FDA [5] - as it reflects conversion to a substantially different stage in the clinical dementia continuum.