PSEN1 and Alzheimer disease: Mutations in APP, PS1 and PS2 are associated with AD [1]–[4], SNCA, LRRK2, PRKN, PINK1 and GBA[5]–[9] are associated with PD; SOD1, TARDP and FUS mutations lead to familial ALS [10]–[12]; frontotemporal dementia and parkinsonism linked to chromosome-17 is associated with MAPT (FTDP-17T) and PGRN mutations (FTDP-17U/GRN) [13]–[15]; and CAG expansion of the HTT gene causes HD [16].