MAPT and early-onset autosomal dominant Alzheimer disease: Many amyloid‐like fibres formed in vitro from proteins associated with disease show an in‐register parallel cross‐β arrangement (Margittai and Langen, 2008); recently however native Tau filaments extracted from the brain of an Alzheimer's Disease patient have been demonstrated to form an elaborate mixed β‐helix/cross‐β structure formed of in‐register, parallel β‐strands (Fitzpatrick et al., 2017).