MAPT and early-onset autosomal dominant Alzheimer disease: Additional forms include Alzheimer’s disease (AD), which is an extracellular filamentous protein (amyloid-β, Aβ) associated tauopathy and chronic traumatic encephalopathy (CTE).2 These conditions are distinguished by the predominant tau isoform [four or three repeat (R) or combined] and distinct structure of tau filaments.3 The involvement of the PNS in neurodegenerative proteinopathies is well-recognized in α-synucleinopathies.