For instance, in PD aggregates consist mainly of α-synuclein (Spillantini et al., 1997), while aggregates of the tau protein and of the Aβ peptide (or amyloid beta in its aggregated form) are both hallmarks of AD (Fitzpatrick et al., 2017; Yang et al., 2022). The gene discussed is MAPT; the disease is Alzheimer disease.